🔔👍 One thing that needs a mention... all 1.6 ratio rockers are not the same coming off the seat. A plain 1.6 might be 1.6, but others check 1.83 off the seat. The valve is opening sooner and quicker.... That is worth a bunch of power. David Vizard explains this well. thanks 👍👍😎😎
Another believer in David Vizard! I've been following his work ever since I first began building engines. If you do what he says you will have about the best engine you can get!
I use Crower Enduro stainless rockers, 7/16 studs with girdles to help reduce deflection and thick wall pushrods. You still lose .050 to .075 lift depending on rpms and engine temperature. Heat makes all metals pliable and deflect more.
I find what you show us super interesting & I do watch your video’s far longer than I should! Some days I need to kick myself in the butt to get going or I miss half my day. Anyway,I did some engine building & street racing like 40 years ago & wish I had someone with your knowledge helping me out,make no mistake you are helping everyone who watches your video’s! I am now to old to put into practice what I learn from you but watching still trips my trigger. Thanks for that!
Most don't realize that incorrect pushrod length changes valve lift by changing the effective rocker arm ratio. For those of you that can do math, think of cosine of the rocker pivot with respect to the valve stem with a different length pushrod. For those of you not math experts, just use your dial indicator next time you degree a cam and substitute a longer/shorter pushrod. If you imagine the angle of the rocker with a REALLY long or short pushrod, the opening/closing parts result in a lot of side motion, not valve depressing.
Yep, he lost me instantly when he said the pushrod was not the correct length for the installed height. Once you compromise correct rocker arm geometry, it's no longer a back to back test for accurate data. I would like to see him go back and correct the rocker arm geometry with a correct length pushrod ( especially since he said the 1.6 rocker was on a 3/8" stud), which exaggerates incorrect geometry even more due to the increased angle.
Exactly why the Ford Cleveland will work with a smaller cam bring than I would normally choose on a SBC. This video has a world of knowledge in it if the viewers are really paying attention to it. You did a great job of letting us see the real deal with this. Thanks
So much knowledge, thank you! I’m working to become a performance builder for small engines like atvs and dirt bikes. I know it’s not exactly the same but the fundamentals!
Nice Job Eric, I really would have stepped up to the 224/230 comp, they have a really nice idle & pull plenty of vacuum, & have a even nicer power curve! If you run a solid roller on the hydraulic cam, set to like 2 thou cold, they are still pretty quiet & pickup around 8 to 12hp! If I remember right, It made like 460/460 I forget what heads, they were brought to us, Might have been box stock Edelbrock? With the performer rpm intake, back when it was new! Basically the same bottom end, scat rotating assembly, & Keith Black pistons, but it was only 2 thousand in the hole. Went in a jacked up square body longbed, Every time I see it out, there’s 150ft long burnouts, from 36in tall tires, I think! Guy is a circle racer, & drives the truck harder than the modified! 😂😂😂😂
Excellent video. I've got a 331 SBF solid roller/shaft rocker going together as soon as the rods come in. Going to be paying WAY more attention to this stuff now. Thank you.
Such a great video i had no idea it was that bad. Im looking into beefier pushrods today. Ive got a solid lift intake is 7.24 with 1.6 rockers and ive got small pushrods im losing some serious lift and im sure it gets much worse higher rpms thanks for this vid
Just putting the finishing touches on a 417 ls carburated build useing a BTR stage 4 na cam .I went with 1.8 ratio comp steel rockers to correct the loss from all of the verables you mentioned and also used 3/8 pushrods.its going to be a interesting dyno session
Steve morris was talking about running thicker walled push rods in a video and i believe it was exactly because of the deflection as you are talking about.
Harland sharp bud.i have a set on my roller small block with .620 Valve travel.250 lbs closed and 650 lb open @ .620.run on the street and 15k miles before I lost a roller tappet @7800 rpm . On the rebuild I noticed I had finally cracked one rocker arm .but it was still working.it cracked at the stud side of the valve spring.
At .050", deflection is minimal compared to open deflection due to lower spring pressures, so durations at .050" aren't affected as greatly as the full lift values. Also, Valve radial clearance should be checked at TDC with piston fully biased (pushed) towards the valve... clay using a valve, or drop a centering tool through the guide, and make a pip in the piston then measure radial from your pip mark with a vernier. (Flat top pistons with small valve reliefs are a clay method candidate)
I read somewhere that retainer flex is most of the loss in lift when measured at the retainer. It would be interesting to take a mock up block without rods and pistons and measure lift at the head of the valve in the bore
There are so many factors to include. You can give me any cam card and I'll prove the numbers are off. Everything from cam core, push rods, plungers, oil type and bleed down, rocker materials and rollers. Can alk effect actual lift. The longer and wall thickness will also effect the readings. HEAT will change everything.even with all those components the same! The numbers will change!!!!!! As the engine runs. Even RPM will change the lift numbers. Think about setting hot last on a solid. How much room is given for heat expansion! Steel rockers will grow more from heat then aluminum will from reflection. A running engine will also stack up more oil on parts at a specific rpm more then at other times. And lastly....Even head bolts and rocker studs will stretch causing even a different number. Your slow roll testing is only getting the mechanical readings without all the hydronic and deflection effects. Even the type of coolant used can change the cam card numbers. Water filled race cars will read different then a car with antifreeze. Just saying....Even top fuel guys will tell you. The car that runs longer before the launch will be slower!
Someone I trust told me for the typical gen1 sbc hydraulic roller (stock dog bone setup) .525-.600 lift, 1.6 rockers, stock old or Delphi ls7 lifters .080" wall 5/16 pushrods you will lose as much as .040" lift in a running engine. Not sure if it's true or not, but it made sense. One thing he did say was make sure your pushrod is not rubbing the head when doing your sweep setup but do not grind anymore off the head for clearance than enough so a piece of notebook paper will clear, said with shaft rockers the tight clearance would actually help stop some harmonics and sort of act as a guide plate and cut down on deflection. Not sure if this is the gospel truth or not? I do know he has been short track racing sbc for over 50 years, and he swears by this method for a hydraulic roller setup in 6500-7000 rpm stuff with .600 or less lift.
When measuring pushrod length, be careful switching between lifters. Push rod cup depth varies in lifters based on brands, and whether they’re mechanical or hydraulic. This is how people mis-measure pushrod length etc.switching for example between a solid flat tappet and hydraulic. For merely opening the valve the pushrod cup depth should have a minor insignificant effect on the results. JD
I like you work and videos I see the one head bolt on center , did you add bolts once you added additional spring pressure? especially the ones near the pivot area (rocker studs)
Hydraulic lifters are designed to pump up at certain rpms. Lots the time I've read they do it so you can put around and have it not run as rough at idle and low rpms, which is understandable. Which in some efi cars it helps to keep the computer from over adjusting
At higher RPM the spring pressure over nose will reduce.. valve may even loft and lift will be bigger than mechanical. Though this test applies for low speeds.
I was shocked to see that much lift gone with an .080” thick pushrod wall. Mostly this video made me happy with my SBC parts selection: .600” theoretical lift, .105” wall pushrods, 7/16” rocker studs, comp ultra pro magnum 1.6” rockers, jomar stud girdle, Johnson Short travel lifters, and beehive springs to cut down on open pressures and hopefully deflection. -Kinda regret not going with 3/8” pushrods but already done and the .105” wall should be fine with my 5,850 rpm peak.
The loss of net lift you are witnessing is from the spring. Turning it over by hand will not deflect the pushrod. That happens while running, worse at rpm.
Nice to see you finally pulled the trigger on some decent exahust manifolds for the S10. Steve Morris made a video about valve train deflection too but I think yours is more detailed tbh. Steve used to work in a Pro Stock team which probably why he only does boost engines now but boost is cheating imo.
When i started building bbc 35 years ago i got laughed at for using huge 71/6 push rods, i said gm must of known something because they used them on the high performance big blocks. Now 35 years in the future people are running the biggest and heaviest push rods they can get lol. Maybe thats why the dyno guy couldn't figure out how my 461 bbc with merlin oval ports 12 .5 compression and a ultradyne roller made 744 hp and 676 torque. I had a holley dominator on a 4150 team g intake, used one of those adaptors. Engine had a gm forged crank and stock 3/8 rods that i polished and installed arp wave loc bolts. 2 bolt maon block with studs. It was in a 37 plymouth coupe i raced all over the Pacific northwest. Car was 3600 lbs with me and would run 10.10 @132 134. Had a th350 we built with all stock parts and just a manual valve body. Those were the good old days. I remember when i got those iron head merlin oval ports that thing were getting serious now lol.
I would like to know are you running 3/8 or 7/16 studs? What push rods .080 or .105 wall, 5/16 or 3/8? I run a stud girdle and i will check to see how much difference i get. Great video.
Stud mount rockers move around too much. Shaft mount steel are my go to. Alloy heads grow and studs stretch so I tend to tighten the lash a little more than spec. Its too hard to work out how much "actual lift" you have. So many variables. Pushrods act like po-go sticks lol.
What rocker arm ratio options are available with the Federal Performance heads and who makes the rockers? Does it make sense to spend more on rockers for more lift or just get a bigger cam?
Is this simply more common in SBC due to it's geometry ? Is this less of a problem where the rocker isn't suspended by the stud and instead solid mounted, such as a shaft mount, or even an OEM LS style with the trunnion mounted solid to the cylinder head, leaving the pushrod (and perhaps the valve tip if no roller) to take the brunt of the abuse and potential deflection ?
This video makes me question what max cam lift you can use regarding valve spring coil bind. I usually see recommended .050 to .060 as a safe buffer but if you don’t get the lift expected could you generally speaking reduce the coil bind buffer value to .040 ?
Hey. Watch you on you all the time. Thanks for your experience and sharing with us. My question is when the engine is running let's say at 5000 rpm, will you possibly regain some lift from the momentum of the valve at speed rather than at idle?. Thanks and have a great day. James
Excellent video Eric, thank you. Am I correct in assuming 90%+ of the deflection shown here is due to the Pushrod and Rocker stud deflecting ? I'm sure very little is due to the actual rocker body. An interesting test would be to check the same dimensions on a shaft rocker application with sufficient pushrods for the spring pressure being used. I hypothesize we would see much less defelection. Thanks again for this excellent demonstration to illustrate your point. Time for a pushrod upgrade.
Aluminum rockers also deflect, and will deflect more than a steel tube, ie pushrod. The spring is what is causing the difference here. Not the pushrod. It is common to see this going from a checker spring to a real spring. Running? Whole different ball of wax.
@@jrdmotorsports9718 Wow.. i always thought aluminium is very rigid? Steel will felx, flex, and flex more.. for a very long time befor failure. Aluminum tends to just stress fracture and fail ? So, if I'm correct, what you mean is, the added stress of the actual valve spring vs the checking spring is causing the rocker to deflect ? .. not the pushrod ? Or rocker stud ?
@@Torquemonster440 No. They ALL deflect. Weakest link breaks first, usually the rocker. Especially if aluminum. If the geometry is correct, parts won't break, unless the quality isn't up to the job for the application.
I always use a 3/8 pushrod on my LS motors regardless, now i want to test if there is actually a lift difference just by switching from a 5/16 to a 3/8 rod
There is some other geometry that goes into play, I did this with one Comp Cam solid roller I bought to do this and I found the solid roller cup is shorter and closer to the cam than the hydraulic. Also Eric placement of your gauge has to be in the exact spot, keep the dial indicator at the same degree of angle is critical for consistent measurements. I think deflection is not a issue just taking a measurement if that's what your saying!?
Interesting, I have checked lift with checking springs and have found a tiny bit more lift. And duration as well. Never done it with proper springs,, well some light ones for baby hydraulic using a solid lifter to check.. And that was very close to the correct numbers. A tin rocker would have been interesting, that style of cam many do use factory rockers. Comparing a 1.5 roller to a factory rocker gains both lift and duration. And yes those Scorpion rockers have more lift. Comparing 1.72 with a diecast Crane gave about 30 thou more lift. So I did not use them. As I knew piston to valve was ok, but that extra lift may well have made it less than ideal. I suspect the lift lost is more pushrod deflection than rocker flex. I also have found that cam cards are conservative on spring pressure. Crane specs decreed 125 on the seat. Engine was a little lazy over 6700. I was given a set of 140lb seat pressure and it gained power over 6000, revved smooth to 7500. And that was above my safe limit! That alone was half a second a lap. I checked the springs that came out and they were between 120 to 125psi. So were still in spec. Though probably started a little heavier. And it was no where near coilbind, the closer to coil bind means A You can lose a cam B have springs go soft quickly, or even break
For one, never rely on what a manufacturer says. Those are not recommendations, more like minimum starting points. Every application for every part is different. Just one way a good builder differs from an assembler. Next, you have it backwards. Too far from bind will break springs. Not the closer you get to it. Its the open pressure that will flatten a cam, not being close to bind, unless you go into bind. Third, any new spring should be installed tighter than normal, as they lose pressure with one heat cycle. Not a lot, but enough. Hope this helps.
My AFR 210 cylinder heads with 1.550 Solid Lift Roller Springs are supposed to be good up to a .710 lift. So my question is, can I actually run a bigger lift camshaft than .710 because I'm not actually getting .710 lift. I'm not going to run that big of lift probably around .650-.680 lift, but theoretically I could run bigger? My heads according to the flow sheet flow the best at .650 lift. Should I shoot for .650 of actual lift?
Ok can you tell me what you think about porting so much that you open the port AND the seat 3-4.5mm wider going from a 35° multiple angle to a 45° single angle (same size valve) larger deeper seats to accommodate the portwork. On the exhaust side. And reducing the lip on the intake back cutting it to the sealing angle. Leaving the lip on back side on the exhaust valves. But over all same size valves. I've posted a short hyperlaps of shaping a bowl. I plan to make a bunch of videos on the next head (about 54 hours into porting alone! ) cast heads are a bear to port
Also. The valves I have two different styles of exhaust valves from DNJ. Same Part numbers but one is black nitride coated and has a much less mass on the back side (used for exhaust side) and the other with same part number non coated has much more mass thus a less aggressive rake from valve stem to the first cut angle ( used on intake side) I chose 24 exhaust valves because they are more resistant to higher power and heat. The order I purchased was messed up and they sent me two types... this gave me the idea to use them to my benefit anyway though they are different castings.
Eric, also wanted to add, the higher the ratio, the more deflection the pushrod will see.. Higher spring rates will always show a decrease in net lift as well.
@@standupoathkeeper6915 All spring rate and spring pressure is for us valve control. Nothing to do with flow of anything. Unfortunately, higher spring rates, stiffer pressures, and higher rocker ratio ALL contribute to pushrod deflection. However, higher ratio rockers couple to aggressive ramp rate lobes, also contribute to other issues, including pole vaulting the pushrod, which you will NOT see on an engine stand.
Crazy thing is.... The flow card you get with a set of heads is inflated too! Soooo... Then begins another debate. "Will adding larger ratio rockers really add more flow and how much?" (If heads aren't ported).
@@standupoathkeeper6915 A flow bench is not a running engine. All I will say about that. There are more important things to consider when deciding on ratio, than what a flow sheet says. You don't build an engine around a flow sheet. Period.
My thinking on this is how much is comming from rockers and how much from pushrods. If you get a lot from pushrods. Then they will be like wet noodles vibrating in the engine. I dont think you can calculate in the loss of lift in the engine. Build ,because as rpms increase spring pressure would effectively decrease. Over revving causes valve float which is effectively zero to no spring pressure.
Great video. I have a 427 CSB with all the good stuff. It has 220 AFR heads. On the dyno it made 650 Hp and 598 lbs torque. It has a hyd roller cam. Intake .400 lift and 251 degree duration at .050. Exhaust is .387 and 255 duration. 33 degree overlap at TDC. Cam card .600 and 304 duration on intake and .581 and 308 duration on exhaust with 1.5 ratio rockers. 110 lobe center. It makes max hp at 6200. Do you think I would be better going to a 1.6 ratio rocker. I'm running steel rockers on it now. Thanks for any input you may have.
Why don't 4V DOHC heads have options for different ratios on their roller rockers? I have a 96 Mustang Cobra and I'm thinking if that were available, I could avoid buying new cams.
Wondering about the push rod lengths here, with different rockers the angle matters, if you start with it too flat your loosing a lot of potential lift, same with it sharp it’s the same. Ideally you’d want the rocker flat- 90 deg to valve at full lift- maximum operating pressure. I’m not saying your wrong here and maybe you considered this and didn’t mention. The card just does the basic math- built “correctly” it’s a lot closer to cam card, by that I mean build it how they did- good video tho.
Hopefully there are still some brands of lifters out there that are fit for purpose, as Ive seen several engines making metal on the runin cycle lately and these were premium lifters from reputable brands! Its the same thing with the rockers too, I dont trust alloys in high stress / high shockload applications, I know a racecar fabricator and he REFUSES to make any braking or suspension related components out of alloy as their hardness values seem to be akin to european cheeses than anything else.
Who needs the right stall, torque multiplication curve and way it holds onto that stall vs efficiency range converter. Used to build some Coan billet bolt together units. Pretty nice stuff. Plenty of know how goes into getting them right.
What you are seeing is not even with it running! Lol. Most don't realize, huge difference between gross lift and net lift. Between deflection and rockers that are not a true ratio, you lose a ton. Not all rockers with the same ratio are created equal. Years ago I did testing for an up and coming rocker company, and tested MANY different brands. Same ratio, big names, and MOST fell short of actual ratio. Some were 1.6 that measured 1.4! SCORPION was the first to catch on and were much bigger than advertised ratio. Now, a lot have caught on. Aluminum is worse than steel, they also grow more than steel, which gains lash when hot vrs. cold. Shafts are always better, as they don't scrub the stud when it takes up lash on a solid roller, and are much more stable. When it comes to pushrods, the bigger and thicker, the better.
Hive you done any work with DOHC engines? I presume there would still be some deflection in the cam, but not to the extent of what you showed here. Love the content, keep it up 👍🏻
Helps a lot. Shaft style rockers are just more stable and smoother at rpm. They also hold lash longer. Aluminum is aluminum however, and still do grow more than steel regardless of style. Bmost people need more pushrod and spring pressure than they think. Bigger the O/D, the thicker the wall, the stiffer it is, the better.
I can't see how it would from a physics point of view. The deflection comes from bending in the rocker arm, pushrod, and compression of the lifter. A stud girdle won't effect any of that. All a girdle can do is stop the studs from moving side-to-side, which isn't a major contributor to deflection.
Stud girdles, as already pointed out, do not do anything for valvetrain deflection. What WASN'T pointed out is that they DO prevent rocker stud deflection, especially in an aluminum head. Not needed in every application, just over a certain point in camshaft profiles.
You'd have to wonder if at least some of this isn't taken into account when you ask a cam grinder for their recommendations. I'm sure that good cam grinders will be recommending based on how the cam works in a typical engine. I noticed that the LSA on the cam was 112 degrees. David Vizard has some videos where he says that LSA is the most important spec and that for a SBC it should be 108, and even less for a stroker. David is very adamant about this saying that he doesn't have an opinion, he has a dyno and more testing than almost everybody else.
The heads can be used on anything, but when you buy a complete head set all put together from what ever brand, they say it’s for flat tappet, or hyd roller, because of the valve springs that are installed on the heads! Flat tappets have much lower pressure on the seat & @ full open, basically the bigger the cam/more aggressive, needs more spring pressure both on the seat/closed & at full lift/open! Just 1 note, if you purchase a cheap set of heads from overseas, never just install them! 99% of the time, the valve job isn’t sealed up, & I’ve seen there brand new springs with as little as 60 lbs on the seat! Way too little pressure, first time the guy drove it, it would only rev to 3500rpm & it bent all the valves that didn’t break, & destroyed the new short block
Don't forget about the seat material. Hydraulic flat tappet 'only' head valve seats can be broken with high spring pressures. A machine shop can put different seats in it for the better pressures.
@@brianholcomb6499 thanks for the reply, im putting together a mild 454 and would really like to see a recent review of the KMJ bbc heads. There are a few videos by "Headbytes Porting" he seems to like them. It would also be interesting to see @Erick Weingartner react to his videos and porting work.
for what it`s worth I threw a set of those as cast on a 388 pump gas motor, open plenum, 750cfm with a small solid roller 242/246 at .050 609lift the customer wanted those heads. We put LS behive springs on with 170lbs on the seat. It dynoed at 491ft/lbs torque at 3100rpm and 500hp at 6600rpm. Me and the dyno operator were surprised
@@generalrobinson8637 The next stroker SBC i do I`m gonna try the cnc`d 225 shocker series, they don`t cost much either. Eric likes the 400/600 lift numbers I like the 500 number. I want it as close to 300cfm or higher and I`d like to be about 90% of the total flow. I`m no cyl head pro, it`s what I have observed over the years besides I mostly do circle track motors. Dynos and flow benches are tools we dont race them. They are indicators and have to be interpreted correctly. Sorry if I beat my gums too much. $1370 no studs, no guide plates.
The other week I saw a video by those meatheads on "Engine Masters" where they put solid rollers on a hydraulic cam to see what would happen. It picked up power at every single point on the curve. It was just a tiny bit, probably nothing you'd ever notice. But it was there. They couldn't figure out why. Now I'm betting it was reduced deflection bumping up the lift.
Not exactly. A solid lifter creates more deflection, not less. A hydraulic lifter rides on a cushion of oil, reducing deflection. Add in the fact it is a hydraulic roller cam which is not nearly as aggressive on the ramp of the lobe as a solid roller does, even ground the same.
@@jrdmotorsports9718 How does solid steel deflect more than a piston floating on oil? There's nothing preventing spring pressure from squeezing oil out of the lifter. I do concede that the softer ramp will cause less deflection. It would be interesting to test, but I don't know how you could measure deflection accurately on a running engine and there's no way to test hydraulic lifters on a stationary engine. If it wasn't deflection, what are your thoughts on why solid lifters produced more power than hydraulics on a hydraulic cam?
@@johnterpack3940 A spring won't squeeze the oil out when it sees continuous oil pressure. It will, however, when you shut it off and the lifter is on the peak of the lobe... Solid steel, WITH LASH. Gets worse the more aggressive the cam is, and the looser the lash is. Lobe hits the lifter, lifter has whatever the lash is and then hits the pushrod. What will give faster? A solid steel lifter, or a long, thin hollow tube? Combine it with high ratio rockers... A solid roller lifter is MUCH lighter, and is more direct with in transferring lobe lift to valve lift. A bit noisier and harder on parts, but the valve sees more of what the cam is trying to make it do, especially at rpm. On the dyno, a hydraulic roller lifter can and has, gone into valve float quicker at rpm and power tanks sooner, like it jumped off a cliff. Solid roller lifters don't. More direct path to the valve. Many other reasons... The cam doesn't know it's a hydraulic, or solid or a unicorn. Just has 1 job. The lifter is the difference.
Think this is why my friend said he was able to use Crane roller (BBC) advertised lift int. 587/Exh. 610 in crate 502 with the GM Hyd. lifters. Others said no due to link arm bind, but was no issue.
@@b.c4066 I noticed that. But this is an unusual amount of split for such a small cam on a wide LSA. I was just wondering what theory was about that. To enhance the top end to make the desired hp goal maybe ?
@@kristjanstefansson2765 I can think of many reasons, but all I can think of is why this term "duration split" keeps being used, when they aren't splitting anything. Two different lobes. Intake and exhaust. No splits. No such term, except for one youtuber who proves his lack of knowledge everytime he speaks. Just sayin.
@@jrdmotorsports9718 would it be a little bit or more than one would think cause I went from a 1050 to a 1250 it works good on the big end just lost 60ft
@@keysautorepair6038 Put it this way, 2 carbs, close in build, for a given application, may be 10hp difference. One may come on sooner and die off up top, usually because it's too small. The other will have the opposite effect. Because it is slightly bigger. Only 1 will work for the application and power range. The difference between the right carb, and a completely wrong carb can be 30-50 or more less the entire curve. So yes a big difference. Now take a 1050 with 2.00" throttle bores, and a 1250 with 2.125" throttle bores and a bigger venturi. The pressure drop is so great at the hit of the throttle, it can't recover fast enough to pull fuel. However, it may make a few peak numbers more at higher peak rpm once it recovers, through the curve it's a dog and doesn't accelerate. Not always about higher rated airflow, it's how the engine accepts the airflow. Huge difference between the two you mentioned. I just built the same 2 carbs for a customer's engine. Going with the 1250.
@@alankirschenbaum768, it's not the CFM that's necessarily changing, it's the duration of the valve opening. Obviously piston clearance needs checking through the cycle. Do an experiment, its very easy, all you need is a dial indicator, measure valve opening duration on one inlet to get a base reading of actual valve opening duration. Then close up the lash on that inlet valve five thou. and re measure valve opening duration. Depending on what cam/ lifter combo, it can make a difference.
Worked for a place that built top level off road engines. Had 2 engine failures due to needle bearings. Jesel lifters. Pushed for them to make the switch to morel bushed. Already had switched to pressing the needles out of the rockers and using bushings. See ya order a lot of Brodix stuff. I'm sure they're on it now but if you order any spread bore blocks, make sure they've been through the HIP (hot isostatic pressing) process. We also honed them before pressing in the sleeves. They were cracking behind the sleeves. Big problem when it happens to a bunch of blocks that weren't HIP...
@@cliffwright9842 I was speaking to their aluminum offerings. Been out of the game for a while, would think that's no longer a thing. As far as the cast iron one you mentioned, I don't know. Dont have any experience with Brodix cast iron blocks. Looks like a pretty good sized discount to comps. Not sure why that is
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You gotta love Erics videos......cuz you ask him what time it is, and he explains how the clock works.....
🔔👍
One thing that needs a mention... all 1.6 ratio rockers are not the same coming off the seat.
A plain 1.6 might be 1.6, but others check 1.83 off the seat. The valve is opening sooner and quicker....
That is worth a bunch of power.
David Vizard explains this well.
thanks 👍👍😎😎
Another believer in David Vizard! I've been following his work ever since I first began building engines. If you do what he says you will have about the best engine you can get!
Great videos!!! Keep me coming please! You seem very good at what you do! Thank you!
Thank you for taking the time to do this. Excellent information!
This has been the most interesting comparison on deflection i have seen. Great stuff.
Never to much to digest, stay on it and chew it longer. Very excited excellent info, never stop learning thank you !
Awesome video. Now that I've watched every video on your page i wait for the new episodes just like waiting for a new favorite tv episode to drop.
I use Crower Enduro stainless rockers, 7/16 studs with girdles to help reduce deflection and thick wall pushrods. You still lose .050 to
.075 lift depending on rpms and engine temperature. Heat makes all metals pliable and deflect more.
I've always wondered about actual amounts of deflection, just never tested. Awesome video!
I have checked this before with stock ls pushrods and the 3/8 .080 and there was a bit of difference in lift values. Awesome video.
I find what you show us super interesting & I do watch your video’s far longer than I should! Some days I need to kick myself in the butt to get going or I miss half my day. Anyway,I did some engine building & street racing like 40 years ago & wish I had someone with your knowledge helping me out,make no mistake you are helping everyone who watches your video’s! I am now to old to put into practice what I learn from you but watching still trips my trigger. Thanks for that!
Most don't realize that incorrect pushrod length changes valve lift by changing the effective rocker arm ratio. For those of you that can do math, think of cosine of the rocker pivot with respect to the valve stem with a different length pushrod. For those of you not math experts, just use your dial indicator next time you degree a cam and substitute a longer/shorter pushrod. If you imagine the angle of the rocker with a REALLY long or short pushrod, the opening/closing parts result in a lot of side motion, not valve depressing.
Yep, he lost me instantly when he said the pushrod was not the correct length for the installed height. Once you compromise correct rocker arm geometry, it's no longer a back to back test for accurate data. I would like to see him go back and correct the rocker arm geometry with a correct length pushrod ( especially since he said the 1.6 rocker was on a 3/8" stud), which exaggerates incorrect geometry even more due to the increased angle.
Exactly why the Ford Cleveland will work with a smaller cam bring than I would normally choose on a SBC. This video has a world of knowledge in it if the viewers are really paying attention to it. You did a great job of letting us see the real deal with this. Thanks
Thank you. I now understand why stainless rockers become a choice in certain applications: aluminum suffers more deflection.
So much knowledge, thank you! I’m working to become a performance builder for small engines like atvs and dirt bikes. I know it’s not exactly the same but the fundamentals!
You just made me feel better for going with stainless rockers. And A.R.P. studs. Thanks.
Lemons builds high quality stuff. Another excellent video.
Nice Job Eric, I really would have stepped up to the 224/230 comp, they have a really nice idle & pull plenty of vacuum, & have a even nicer power curve! If you run a solid roller on the hydraulic cam, set to like 2 thou cold, they are still pretty quiet & pickup around 8 to 12hp! If I remember right, It made like 460/460 I forget what heads, they were brought to us, Might have been box stock Edelbrock? With the performer rpm intake, back when it was new! Basically the same bottom end, scat rotating assembly, & Keith Black pistons, but it was only 2 thousand in the hole. Went in a jacked up square body longbed, Every time I see it out, there’s 150ft long burnouts, from 36in tall tires, I think! Guy is a circle racer, & drives the truck harder than the modified! 😂😂😂😂
My new favorite youtube guy!!
Excellent video. I've got a 331 SBF solid roller/shaft rocker going together as soon as the rods come in. Going to be paying WAY more attention to this stuff now. Thank you.
Check with David Vizard the SBF EXPERT.
@@hotrodray6802 Check what?
Such a great video i had no idea it was that bad. Im looking into beefier pushrods today. Ive got a solid lift intake is 7.24 with 1.6 rockers and ive got small pushrods im losing some serious lift and im sure it gets much worse higher rpms thanks for this vid
Just putting the finishing touches on a 417 ls carburated build useing a BTR stage 4 na cam .I went with 1.8 ratio comp steel rockers to correct the loss from all of the verables you mentioned and also used 3/8 pushrods.its going to be a interesting dyno session
STREET daily driver blueprint plan for 2nd gen camaro.
Blueprinted Perfect 9.025" finished deck '010' 015 025 block350, 0.002" above deck pistons. Forged crank offset ground to 362 c.i. SBC 4.040" bore. PromaXX Project X215 heads, 2.08" intake valve unshrouded, .150" dome with relief. XR288HR on 108 LSA, PRW 1.65 roller rockers = 1.83:01 Off seat exaggerating ramp rate. Victor JR , 850cfm- VRS. Switching to 400 style bore block in tall deck block and Dominator 1050cfm.
Very interesting & informative
Very informative, thanks.
I love all these tech videos
Great video
Very good video sir
Steve morris was talking about running thicker walled push rods in a video and i believe it was exactly because of the deflection as you are talking about.
Wow thanks foe the tips.
Turn left to go right! Got it!
Harland sharp bud.i have a set on my roller small block with .620 Valve travel.250 lbs closed and 650 lb open @ .620.run on the street and 15k miles before I lost a roller tappet @7800 rpm .
On the rebuild I noticed I had finally cracked one rocker arm .but it was still working.it cracked at the stud side of the valve spring.
Very good explaining valve train physics! vs. theoretical Eric
Im sharing the hell outta this vid great info
Thanks for watching.
At .050", deflection is minimal compared to open deflection due to lower spring pressures, so durations at .050" aren't affected as greatly as the full lift values. Also, Valve radial clearance should be checked at TDC with piston fully biased (pushed) towards the valve... clay using a valve, or drop a centering tool through the guide, and make a pip in the piston then
measure radial from your pip mark with a vernier. (Flat top pistons with small valve reliefs are a clay method candidate)
I read somewhere that retainer flex is most of the loss in lift when measured at the retainer. It would be interesting to take a mock up block without rods and pistons and measure lift at the head of the valve in the bore
There are so many factors to include. You can give me any cam card and I'll prove the numbers are off. Everything from cam core, push rods, plungers, oil type and bleed down, rocker materials and rollers. Can alk effect actual lift. The longer and wall thickness will also effect the readings. HEAT will change everything.even with all those components the same! The numbers will change!!!!!! As the engine runs. Even RPM will change the lift numbers. Think about setting hot last on a solid. How much room is given for heat expansion! Steel rockers will grow more from heat then aluminum will from reflection. A running engine will also stack up more oil on parts at a specific rpm more then at other times. And lastly....Even head bolts and rocker studs will stretch causing even a different number.
Your slow roll testing is only getting the mechanical readings without all the hydronic and deflection effects.
Even the type of coolant used can change the cam card numbers. Water filled race cars will read different then a car with antifreeze.
Just saying....Even top fuel guys will tell you. The car that runs longer before the launch will be slower!
Someone I trust told me for the typical gen1 sbc hydraulic roller (stock dog bone setup) .525-.600 lift, 1.6 rockers, stock old or Delphi ls7 lifters .080" wall 5/16 pushrods you will lose as much as .040" lift in a running engine. Not sure if it's true or not, but it made sense. One thing he did say was make sure your pushrod is not rubbing the head when doing your sweep setup but do not grind anymore off the head for clearance than enough so a piece of notebook paper will clear, said with shaft rockers the tight clearance would actually help stop some harmonics and sort of act as a guide plate and cut down on deflection. Not sure if this is the gospel truth or not? I do know he has been short track racing sbc for over 50 years, and he swears by this method for a hydraulic roller setup in 6500-7000 rpm stuff with .600 or less lift.
You forgot loft😉
@@treyrags Did you watch the whole video? He covered it…
@@adamarndt7617 yes I did. I was referring to Inspector Business' list of things, not Eric.
Yes. Among a host of things.
Now I've got to look see if you have a collector length/ exhaust length video.
When measuring pushrod length, be careful switching between lifters. Push rod cup depth varies in lifters based on brands, and whether they’re mechanical or hydraulic. This is how people mis-measure pushrod length etc.switching for example between a solid flat tappet and hydraulic.
For merely opening the valve the pushrod cup depth should have a minor insignificant effect on the results. JD
Pushrod cup depth absolutely varies. You bring up an extremely important but often overlooked point!
Wow, the amount of deflection was much greater than I would've thought!
It's even worse when the engine is running, especially at rpm. Most don't realize just how much you lose.
I think my next engine project will have overhead cams, LOL.
@@jrdmotorsports9718 add heat and metal gets pliable too.
@@stuartbuckley8720 Everything does.. lol
I like you work and videos
I see the one head bolt on center , did you add bolts once you added additional spring pressure? especially the ones near the pivot area (rocker studs)
Hydraulic lifters are designed to pump up at certain rpms. Lots the time I've read they do it so you can put around and have it not run as rough at idle and low rpms, which is understandable. Which in some efi cars it helps to keep the computer from over adjusting
At higher RPM the spring pressure over nose will reduce.. valve may even loft and lift will be bigger than mechanical.
Though this test applies for low speeds.
I was shocked to see that much lift gone with an .080” thick pushrod wall.
Mostly this video made me happy with my SBC parts selection: .600” theoretical lift, .105” wall pushrods, 7/16” rocker studs, comp ultra pro magnum 1.6” rockers, jomar stud girdle, Johnson Short travel lifters, and beehive springs to cut down on open pressures and hopefully deflection. -Kinda regret not going with 3/8” pushrods but already done and the .105” wall should be fine with my 5,850 rpm peak.
The loss of net lift you are witnessing is from the spring. Turning it over by hand will not deflect the pushrod. That happens while running, worse at rpm.
Nice to see you finally pulled the trigger on some decent exahust manifolds for the S10.
Steve Morris made a video about valve train deflection too but I think yours is more detailed tbh.
Steve used to work in a Pro Stock team which probably why he only does boost engines now but boost is cheating imo.
Thx again
When i started building bbc 35 years ago i got laughed at for using huge 71/6 push rods, i said gm must of known something because they used them on the high performance big blocks. Now 35 years in the future people are running the biggest and heaviest push rods they can get lol. Maybe thats why the dyno guy couldn't figure out how my 461 bbc with merlin oval ports 12 .5 compression and a ultradyne roller made 744 hp and 676 torque. I had a holley dominator on a 4150 team g intake, used one of those adaptors. Engine had a gm forged crank and stock 3/8 rods that i polished and installed arp wave loc bolts. 2 bolt maon block with studs. It was in a 37 plymouth coupe i raced all over the Pacific northwest. Car was 3600 lbs with me and would run 10.10 @132 134. Had a th350 we built with all stock parts and just a manual valve body. Those were the good old days. I remember when i got those iron head merlin oval ports that thing were getting serious now lol.
I would like to know are you running 3/8 or 7/16 studs? What push rods .080 or .105 wall, 5/16 or 3/8? I run a stud girdle and i will check to see how much difference i get. Great video.
Stud mount rockers move around too much. Shaft mount steel are my go to. Alloy heads grow and studs stretch so I tend to tighten the lash a little more than spec. Its too hard to work out how much "actual lift" you have. So many variables. Pushrods act like po-go sticks lol.
What rocker arm ratio options are available with the Federal Performance heads and who makes the rockers? Does it make sense to spend more on rockers for more lift or just get a bigger cam?
The faster you can raise the valve, generally the more power you make.
Is this simply more common in SBC due to it's geometry ? Is this less of a problem where the rocker isn't suspended by the stud and instead solid mounted, such as a shaft mount, or even an OEM LS style with the trunnion mounted solid to the cylinder head, leaving the pushrod (and perhaps the valve tip if no roller) to take the brunt of the abuse and potential deflection ?
This video makes me question what max cam lift you can use regarding valve spring coil bind. I usually see recommended .050 to .060 as a safe buffer but if you don’t get the lift expected could you generally speaking reduce the coil bind buffer value to .040 ?
Hey. Watch you on you all the time. Thanks for your experience and sharing with us. My question is when the engine is running let's say at 5000 rpm, will you possibly regain some lift from the momentum of the valve at speed rather than at idle?. Thanks and have a great day. James
Thats called loft and probably not.
I wore them rocker out with my solid roller cam in 6 months I went to comp golds
Have u ever tested the comp ultra pro magnum vs a shaft rocker in a deflection test?
How much worse does it get when you go to a reduced base circle sbc cam with heavy 1.550 double valve springs, like comp 943's?
Excellent video Eric, thank you. Am I correct in assuming 90%+ of the deflection shown here is due to the Pushrod and Rocker stud deflecting ? I'm sure very little is due to the actual rocker body. An interesting test would be to check the same dimensions on a shaft rocker application with sufficient pushrods for the spring pressure being used. I hypothesize we would see much less defelection. Thanks again for this excellent demonstration to illustrate your point. Time for a pushrod upgrade.
Aluminum rockers also deflect, and will deflect more than a steel tube, ie pushrod. The spring is what is causing the difference here. Not the pushrod. It is common to see this going from a checker spring to a real spring. Running? Whole different ball of wax.
@@jrdmotorsports9718 Wow.. i always thought aluminium is very rigid? Steel will felx, flex, and flex more.. for a very long time befor failure. Aluminum tends to just stress fracture and fail ? So, if I'm correct, what you mean is, the added stress of the actual valve spring vs the checking spring is causing the rocker to deflect ? .. not the pushrod ? Or rocker stud ?
@@Torquemonster440 No. They ALL deflect. Weakest link breaks first, usually the rocker. Especially if aluminum. If the geometry is correct, parts won't break, unless the quality isn't up to the job for the application.
Did you try a stamped steel 1:5 rocker to see if you exhibited the same results?
I always use a 3/8 pushrod on my LS motors regardless, now i want to test if there is actually a lift difference just by switching from a 5/16 to a 3/8 rod
There is some other geometry that goes into play, I did this with one Comp Cam solid roller I bought to do this and I found the solid roller cup is shorter and closer to the cam than the hydraulic. Also Eric placement of your gauge has to be in the exact spot, keep the dial indicator at the same degree of angle is critical for consistent measurements. I think deflection is not a issue just taking a measurement if that's what your saying!?
Interesting, I have checked lift with checking springs and have found a tiny bit more lift. And duration as well. Never done it with proper springs,, well some light ones for baby hydraulic using a solid lifter to check.. And that was very close to the correct numbers.
A tin rocker would have been interesting, that style of cam many do use factory rockers. Comparing a 1.5 roller to a factory rocker gains both lift and duration.
And yes those Scorpion rockers have more lift. Comparing 1.72 with a diecast Crane gave about 30 thou more lift. So I did not use them. As I knew piston to valve was ok, but that extra lift may well have made it less than ideal.
I suspect the lift lost is more pushrod deflection than rocker flex.
I also have found that cam cards are conservative on spring pressure. Crane specs decreed 125 on the seat. Engine was a little lazy over 6700. I was given a set of 140lb seat pressure and it gained power over 6000, revved smooth to 7500. And that was above my safe limit! That alone was half a second a lap.
I checked the springs that came out and they were between 120 to 125psi. So were still in spec. Though probably started a little heavier. And it was no where near coilbind, the closer to coil bind means A You can lose a cam B have springs go soft quickly, or even break
For one, never rely on what a manufacturer says. Those are not recommendations, more like minimum starting points. Every application for every part is different. Just one way a good builder differs from an assembler.
Next, you have it backwards. Too far from bind will break springs. Not the closer you get to it. Its the open pressure that will flatten a cam, not being close to bind, unless you go into bind.
Third, any new spring should be installed tighter than normal, as they lose pressure with one heat cycle. Not a lot, but enough. Hope this helps.
so how is it when you degree a cam you come up with what's on the cam card?
HI ERIC WHAT DO YOU THINK OF CONICAL SPRINGS
My AFR 210 cylinder heads with 1.550 Solid Lift Roller Springs are supposed to be good up to a .710 lift. So my question is, can I actually run a bigger lift camshaft than .710 because I'm not actually getting .710 lift. I'm not going to run that big of lift probably around .650-.680 lift, but theoretically I could run bigger? My heads according to the flow sheet flow the best at .650 lift. Should I shoot for .650 of actual lift?
Ok can you tell me what you think about porting so much that you open the port AND the seat 3-4.5mm wider going from a 35° multiple angle to a 45° single angle (same size valve) larger deeper seats to accommodate the portwork. On the exhaust side. And reducing the lip on the intake back cutting it to the sealing angle. Leaving the lip on back side on the exhaust valves.
But over all same size valves.
I've posted a short hyperlaps of shaping a bowl. I plan to make a bunch of videos on the next head (about 54 hours into porting alone! ) cast heads are a bear to port
Also. The valves I have two different styles of exhaust valves from DNJ. Same Part numbers but one is black nitride coated and has a much less mass on the back side (used for exhaust side) and the other with same part number non coated has much more mass thus a less aggressive rake from valve stem to the first cut angle ( used on intake side) I chose 24 exhaust valves because they are more resistant to higher power and heat. The order I purchased was messed up and they sent me two types... this gave me the idea to use them to my benefit anyway though they are different castings.
Eric, also wanted to add, the higher the ratio, the more deflection the pushrod will see.. Higher spring rates will always show a decrease in net lift as well.
Ya gotta have higher spring rate to achieve more flow and use of larger rockers right?
@@standupoathkeeper6915 All spring rate and spring pressure is for us valve control. Nothing to do with flow of anything. Unfortunately, higher spring rates, stiffer pressures, and higher rocker ratio ALL contribute to pushrod deflection. However, higher ratio rockers couple to aggressive ramp rate lobes, also contribute to other issues, including pole vaulting the pushrod, which you will NOT see on an engine stand.
Crazy thing is.... The flow card you get with a set of heads is inflated too! Soooo... Then begins another debate. "Will adding larger ratio rockers really add more flow and how much?" (If heads aren't ported).
@@standupoathkeeper6915 A flow bench is not a running engine. All I will say about that. There are more important things to consider when deciding on ratio, than what a flow sheet says. You don't build an engine around a flow sheet. Period.
@@jrdmotorsports9718 my point was..... Will rockers truly effect hp/tq if your heads are too small to accommodate even the smallest gains.
My thinking on this is how much is comming from rockers and how much from pushrods. If you get a lot from pushrods. Then they will be like wet noodles vibrating in the engine. I dont think you can calculate in the loss of lift in the engine. Build ,because as rpms increase spring pressure would effectively decrease. Over revving causes valve float which is effectively zero to no spring pressure.
Can ı use 294hr camshaft with 1.6 rockers on 3973487X chevy old heads?
Wil you lose lift with the actual strong spring resisting ?
Great video. I have a 427 CSB with all the good stuff. It has 220 AFR heads. On the dyno it made 650 Hp and 598 lbs torque. It has a hyd roller cam. Intake .400 lift and 251 degree duration at .050. Exhaust is .387 and 255 duration. 33 degree overlap at TDC. Cam card .600 and 304 duration on intake and .581 and 308 duration on exhaust with 1.5 ratio rockers. 110 lobe center. It makes max hp at 6200. Do you think I would be better going to a 1.6 ratio rocker. I'm running steel rockers on it now. Thanks for any input you may have.
Yes
Why don't 4V DOHC heads have options for different ratios on their roller rockers? I have a 96 Mustang Cobra and I'm thinking if that were available, I could avoid buying new cams.
So while in motion is even more deflection losses due to valve train mases?
Wondering about the push rod lengths here, with different rockers the angle matters, if you start with it too flat your loosing a lot of potential lift, same with it sharp it’s the same. Ideally you’d want the rocker flat- 90 deg to valve at full lift- maximum operating pressure. I’m not saying your wrong here and maybe you considered this and didn’t mention. The card just does the basic math- built “correctly” it’s a lot closer to cam card, by that I mean build it how they did- good video tho.
Hopefully there are still some brands of lifters out there that are fit for purpose, as Ive seen several engines making metal on the runin cycle lately and these were premium lifters from reputable brands! Its the same thing with the rockers too, I dont trust alloys in high stress / high shockload applications, I know a racecar fabricator and he REFUSES to make any braking or suspension related components out of alloy as their hardness values seem to be akin to european cheeses than anything else.
All steels are an alloy.
Is 40/50 thou deflection common?
👍👍👍👍👍
Still need to put you the correct converter in that thing.
Who needs the right stall, torque multiplication curve and way it holds onto that stall vs efficiency range converter.
Used to build some Coan billet bolt together units. Pretty nice stuff. Plenty of know how goes into getting them right.
I have found .024 thou. Difference between 2 different companys 1.6 rockers !!
Any cam profile suggestions for getting 600hp from a Stealth headed, shaft rocker, 10:1 452 cid Dodge to run the Silver State Classic ?
Buy a chevy?!
What you are seeing is not even with it running! Lol. Most don't realize, huge difference between gross lift and net lift. Between deflection and rockers that are not a true ratio, you lose a ton. Not all rockers with the same ratio are created equal. Years ago I did testing for an up and coming rocker company, and tested MANY different brands. Same ratio, big names, and MOST fell short of actual ratio. Some were 1.6 that measured 1.4! SCORPION was the first to catch on and were much bigger than advertised ratio. Now, a lot have caught on. Aluminum is worse than steel, they also grow more than steel, which gains lash when hot vrs. cold. Shafts are always better, as they don't scrub the stud when it takes up lash on a solid roller, and are much more stable. When it comes to pushrods, the bigger and thicker, the better.
Let's not forget beehive or conical springs.
what do you think about the assault heads? are they good quality? can you run them out of the box?
They seem ok
Hive you done any work with DOHC engines? I presume there would still be some deflection in the cam, but not to the extent of what you showed here.
Love the content, keep it up 👍🏻
Nope not my cup of tea.
So a BSR shaft mount rockers and 3/8”.135 min wall pushrods helps a little????
Helps a lot. Shaft style rockers are just more stable and smoother at rpm. They also hold lash longer. Aluminum is aluminum however, and still do grow more than steel regardless of style. Bmost people need more pushrod and spring pressure than they think. Bigger the O/D, the thicker the wall, the stiffer it is, the better.
Eric, does a stud girdle help with deflection and lift loss?
I can't see how it would from a physics point of view. The deflection comes from bending in the rocker arm, pushrod, and compression of the lifter. A stud girdle won't effect any of that. All a girdle can do is stop the studs from moving side-to-side, which isn't a major contributor to deflection.
Stud girdles, as already pointed out, do not do anything for valvetrain deflection. What WASN'T pointed out is that they DO prevent rocker stud deflection, especially in an aluminum head. Not needed in every application, just over a certain point in camshaft profiles.
Can u do those same tests with a stud girdle on there?
You'd have to wonder if at least some of this isn't taken into account when you ask a cam grinder for their recommendations. I'm sure that good cam grinders will be recommending based on how the cam works in a typical engine.
I noticed that the LSA on the cam was 112 degrees. David Vizard has some videos where he says that LSA is the most important spec and that for a SBC it should be 108, and even less for a stroker. David is very adamant about this saying that he doesn't have an opinion, he has a dyno and more testing than almost everybody else.
That’s far from true both on Lsa and dyno tests.
why do some cylinder heads say the are for flat tappet only? is it the pushrod guide setup or spring package? Thanks
The heads can be used on anything, but when you buy a complete head set all put together from what ever brand, they say it’s for flat tappet, or hyd roller, because of the valve springs that are installed on the heads! Flat tappets have much lower pressure on the seat & @ full open, basically the bigger the cam/more aggressive, needs more spring pressure both on the seat/closed & at full lift/open! Just 1 note, if you purchase a cheap set of heads from overseas, never just install them! 99% of the time, the valve job isn’t sealed up, & I’ve seen there brand new springs with as little as 60 lbs on the seat! Way too little pressure, first time the guy drove it, it would only rev to 3500rpm & it bent all the valves that didn’t break, & destroyed the new short block
Don't forget about the seat material. Hydraulic flat tappet 'only' head valve seats can be broken with high spring pressures. A machine shop can put different seats in it for the better pressures.
@@brianholcomb6499 thanks for the reply, im putting together a mild 454 and would really like to see a recent review of the KMJ bbc heads. There are a few videos by "Headbytes Porting" he seems to like them. It would also be interesting to see @Erick Weingartner react to his videos and porting work.
I like to see if shaft mount rockers make that much difference. i run t&d chromoly
They do. Steel also deflects a ton less than aluminum. Especially at temp.
Have you ever port Promaxx 200 heads and if so what do think about them and flow rates?
for what it`s worth I threw a set of those as cast on a 388 pump gas motor, open plenum, 750cfm with a small solid roller 242/246 at .050 609lift the customer wanted those heads. We put LS behive springs on with 170lbs on the seat. It dynoed at 491ft/lbs torque at 3100rpm and 500hp at 6600rpm. Me and the dyno operator were surprised
@@edpetrocelli2633 wow that’s pretty descent from a 200 runner and 2.02 valve. Thanks
I have ported the Brodix ik 200 which is what the promaxx copied. I just have not ported the promax.
@@generalrobinson8637 The next stroker SBC i do I`m gonna try the cnc`d 225 shocker series, they don`t cost much either. Eric likes the 400/600 lift numbers I like the 500 number. I want it as close to 300cfm or higher and I`d like to be about 90% of the total flow. I`m no cyl head pro, it`s what I have observed over the years besides I mostly do circle track motors. Dynos and flow benches are tools we dont race them. They are indicators and have to be interpreted correctly. Sorry if I beat my gums too much. $1370 no studs, no guide plates.
@@edpetrocelli2633 yeah they seem to be some goof heads, I haven’t heard anything bad about them yet
But won't RPM's and heat from a running engine make those numbers fall closer in line to where they're supposed to be?
No, just the opposite. You lose more. The difference in valve lift you see here is just from the spring, turning it over by hand.
Lash closes up significantly at operating temperature.
It actually opens with aluminum heads.
The other week I saw a video by those meatheads on "Engine Masters" where they put solid rollers on a hydraulic cam to see what would happen. It picked up power at every single point on the curve. It was just a tiny bit, probably nothing you'd ever notice. But it was there. They couldn't figure out why. Now I'm betting it was reduced deflection bumping up the lift.
Not exactly. A solid lifter creates more deflection, not less. A hydraulic lifter rides on a cushion of oil, reducing deflection. Add in the fact it is a hydraulic roller cam which is not nearly as aggressive on the ramp of the lobe as a solid roller does, even ground the same.
@@jrdmotorsports9718 How does solid steel deflect more than a piston floating on oil? There's nothing preventing spring pressure from squeezing oil out of the lifter. I do concede that the softer ramp will cause less deflection. It would be interesting to test, but I don't know how you could measure deflection accurately on a running engine and there's no way to test hydraulic lifters on a stationary engine.
If it wasn't deflection, what are your thoughts on why solid lifters produced more power than hydraulics on a hydraulic cam?
@@johnterpack3940 A spring won't squeeze the oil out when it sees continuous oil pressure. It will, however, when you shut it off and the lifter is on the peak of the lobe... Solid steel, WITH LASH. Gets worse the more aggressive the cam is, and the looser the lash is. Lobe hits the lifter, lifter has whatever the lash is and then hits the pushrod. What will give faster? A solid steel lifter, or a long, thin hollow tube? Combine it with high ratio rockers...
A solid roller lifter is MUCH lighter, and is more direct with in transferring lobe lift to valve lift. A bit noisier and harder on parts, but the valve sees more of what the cam is trying to make it do, especially at rpm. On the dyno, a hydraulic roller lifter can and has, gone into valve float quicker at rpm and power tanks sooner, like it jumped off a cliff. Solid roller lifters don't. More direct path to the valve. Many other reasons... The cam doesn't know it's a hydraulic, or solid or a unicorn. Just has 1 job. The lifter is the difference.
Solid lifter has some amount of cold lash while the hydraulic has oil with some amount of compressible air entrainment.
Think this is why my friend said he was able to use Crane roller (BBC) advertised lift int. 587/Exh. 610 in crate 502 with the GM Hyd. lifters. Others said no due to link arm bind, but was no issue.
Why is there so much duration split between the intake and exhaust ? Also is the engine going to the dyno ?
He mentioned mild, power brakes, for his sister, just a docile street car, full exhaust system quiet. But he wants it to make around 400 hp.
@@b.c4066 I noticed that. But this is an unusual amount of split for such a small cam on a wide LSA. I was just wondering what theory was about that. To enhance the top end to make the desired hp goal maybe ?
@@kristjanstefansson2765 I can think of many reasons, but all I can think of is why this term "duration split" keeps being used, when they aren't splitting anything. Two different lobes. Intake and exhaust. No splits. No such term, except for one youtuber who proves his lack of knowledge everytime he speaks. Just sayin.
Hey Eric would to big of a carburetor lose a lot of low end torque like say going from a 1050 to a 1250
Absolutely!
@@jrdmotorsports9718 would it be a little bit or more than one would think cause I went from a 1050 to a 1250 it works good on the big end just lost 60ft
@@keysautorepair6038 Put it this way, 2 carbs, close in build, for a given application, may be 10hp difference. One may come on sooner and die off up top, usually because it's too small. The other will have the opposite effect. Because it is slightly bigger. Only 1 will work for the application and power range. The difference between the right carb, and a completely wrong carb can be 30-50 or more less the entire curve. So yes a big difference.
Now take a 1050 with 2.00" throttle bores, and a 1250 with 2.125" throttle bores and a bigger venturi. The pressure drop is so great at the hit of the throttle, it can't recover fast enough to pull fuel. However, it may make a few peak numbers more at higher peak rpm once it recovers, through the curve it's a dog and doesn't accelerate. Not always about higher rated airflow, it's how the engine accepts the airflow.
Huge difference between the two you mentioned. I just built the same 2 carbs for a customer's engine. Going with the 1250.
Holy defection batman never gave it a thought thanks
Most don't.
Just reduce the lash, its always more than needed for heat growth
@@alankirschenbaum768, it's not the CFM that's necessarily changing, it's the duration of the valve opening. Obviously piston clearance needs checking through the cycle. Do an experiment, its very easy, all you need is a dial indicator, measure valve opening duration on one inlet to get a base reading of actual valve opening duration. Then close up the lash on that inlet valve five thou. and re measure valve opening duration. Depending on what cam/ lifter combo, it can make a difference.
Morel Lifters 👏
I’m starting to switch to BAM lifters though.
@@WeingartnerRacing Thanks, I'll check them out. That just an availability thing or what's prompted the change?
Worked for a place that built top level off road engines. Had 2 engine failures due to needle bearings. Jesel lifters. Pushed for them to make the switch to morel bushed. Already had switched to pressing the needles out of the rockers and using bushings.
See ya order a lot of Brodix stuff. I'm sure they're on it now but if you order any spread bore blocks, make sure they've been through the HIP (hot isostatic pressing) process. We also honed them before pressing in the sleeves. They were cracking behind the sleeves. Big problem when it happens to a bunch of blocks that weren't HIP...
@@sc358. Is that why they're so cheap 1600 bucks for a new 350 main 4.125 bore?
@@cliffwright9842 I was speaking to their aluminum offerings. Been out of the game for a while, would think that's no longer a thing.
As far as the cast iron one you mentioned, I don't know. Dont have any experience with Brodix cast iron blocks. Looks like a pretty good sized discount to comps. Not sure why that is