Cam companies still have not got it right!
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- เผยแพร่เมื่อ 24 ก.ค. 2024
- In this, episode 57 of PowerTec 10, DV high lights the lack of any real accuracy of the quoted cam timing #'s compared to what the optimum timing is. There is no guarantee that the cam card that comes with your new cam has the optimum cam setting on it. In fact the cam advance so often called for when the engine concerned is a domestic V8 is about half the time as much as 2 degrees off what the engine actually needs for optimum results. Here DV explains why the cam is not the real controlling factor here. The heads are and in his usual style he makes a complex subject easy to understand. Follow along and get the benefits from one of those rare people who have thousands of cam tests under their belt.
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Before the internet, books were the way and this guy was king. His books gave my the knowledge AND confidence to replace a flat cam in an old Impala. Turned out great. First time I was ever that deep in a motor and none of my usual mentors around, because I was living across the country. I didn't set any speed records getting it installed, but I broke it in right and it outlived the car. Decades later and the information I gleaned from his books has proven to be correct, over and over.
As far back as the 80s I was building British Ford 4 cylinder motors and Mini A series engines using Vizard's books and magazine articles. I still have his book on A series engine building written in the 70s!
TH-cam needs a love button! I'm not a racer or engine builder, just a guy who is always looking for ways to increase the performance of a street car (1993 Mustang LX) while retaining stock-like driveability. Mr. Vizard's video's really get my mind fired up!
I appreciate all the knowledge you provide for us David! 👍
Thanks, David. You described perfectly how the flow curve differences prescribe different cam event timing.
Thanks again DV, really gaining a lot from the head/ cam video set. Cheers
This is the first video I have seen from your channel and I am very impressed and very interested in learning more about cam timing
Another great video. Looking forward to upcoming episodes.
Awesome video David. Looking forward to the SBF cam information.
Very good explanation on timing events sir .looking forward to more..
Thanks David, lot's of tech stuff takes a long time to sink in and I understand your message loud and clear.
I like your books that show the exact cam specs needed to get the power level that the individual wants to have.
As always your explanations are excellent! Thank you!
Great stuff. Would love one touching on the discrepancies of the peak power and power curves etc. Love how all this is mostly logical yet still overlooked by most. Great stuff.
One of the few people who really know things... So good to see you on TH-cam!
I'm loving all your Powertech 10 U-tube vids. Now I'm racking my mind trying to adapt these golden bits of knowledge to my 4cy N/A horizontally opposed engine :)
Scooby??
David Sir Thank you very much for sharing your knowledge with us. I hope you have a restful Sunday. Always be safe in your travels and Take Care
he is dead..
Hi Dave glad to see you're still at the top of your game sorry to hear of your loss. I thank you for giving me that enquiring mind for tuning. My best wishes to you and your family for giving so much for so long, you are godlike to those who know.
Excellent content David. Truly informative
Great information! Found you just before I was about to do a couple of rebuilds. Think I'll Learn a little more from this gentleman first.
Thank you I enjoy all your videos it's such good advice from a true master of engine building .I bracket race so I just stick the cams in dot to dot and go for a ride ! I can only imagine how many horses if left on the table all these years.! Still go quite fast .someday I may have a pro assemble one for me .bo far I have been happy that my stuff stays together !! Thank you David
The second degree wheel is for degrees of cam overlap of the intake and exhaust valves ( when both valves are open)
Wow... you learn something new every day!
The inner ring of the degree wheel allows one to follow the valve lobe centerline, open and closing events in relation to crankshaft degrees. It is a numerical representation of a cam lobe in terms of duration. Looks very handy to use.
I built a small block using the tips from your book years ago . Ported the heads like you said and picked a solid lifter cam from your book . It ran better than most big blocks around me thanks for everything you do
I ported a 1275 Austin Mini cylinder head using David's information. the performance was outstandingly good on a standard cam and standard twin SU carbs. I can only imagine how good it would have been with a Vizard cam and manifolds.
Have you ever driven a big block car? I can tell you a healthy big block will absolutely trounce any small block. I have a 1970 Corvette with pretty much a 350 LT-1 engine in it. I thought it was kind of a dog. My other car a '70 Chevelle SS 454, OMG it is like night and day. Feels twice as strong as the Corvette ever was.
Yes I have .
And my small block was no where near stock . It was able to pit my 3150 with me in it camaro into the 10s
@@ekitching 434 sbc with fully ported AFRs or Brodix dragonslayers puts it in the 700 to 800hp range quite handily especially with 12.5 to 1 compression or more. Big blocks can get there pretty easily also but the small blocks Im used to are no slouch especially when power adders are also involved
Love to see the “Cam Scam” Article and to know where to get a current version of the cam selection software. Thank you.
Great info and what you are describing is the benefit of a custom ground cam, i only spec a cam after I have the entire setup decided. I get what you are saying about cam companies but how they are designing them for the majority of engines, they don’t know what each engine setup is so have to make something that satisfies most setups. Not everyone has ability to dyno every engine to dial in the cam but I agree this is the best way to do it.
Thank u David for sharing your amazing knowage...!...stay healthy..reguards,Brian
David great video in some classes you can't change the seat angle tech inspectors are supposed to check this if an engine is challenged and torn down there is a tolerance allowed we stuck to the high side of this tolerance just for the low lift flow advantage..not cheating but skirting the line for shure....LOL
This was great and confirms what ive thought for 20 years. Good stuff D.V.
Schnieder Cam asked me everything.. talked me into a smaller cam than everyone else for my hot forged internal balanced 11/1 406 sbc with 220cc intake runner cnc ported heads that flow benched at 315cfm at .600 lift. 71cc chambers. .038 quench 93 octane no pinging.. I'm so glad they did. It's a 292 adv 70° overlap but ONLY 238/236 @ .050 and 110 lsa degreed installed at 108 and .622 lift. It makes power to 6800.
And my cam was the last thing I bought. But had I had access to a dyno I would've played with the degreeing more. But I don't and don't have the $ to do it
@@DiscoGreen so true. How many of us have the bucks to put all our engines on dynos and search for that last bit of HP.
Mr Vizard I’m privileged to be able to view vids that you produce, please keep on keeping on .
That makes total sense and I would have never thought of that without this video
In the hope of giving you something from which you may benefit, I have liked, subscribed, turned on notifications and commented.. The information you give is gold. Thankyou. Ken
Thanks good stuff I was Engine builder for years never thought much about valve seat angle in that way it was mostly about seating and heat range thanks l.d.k.
Can’t wait to see the next two.
I do not usually respond to to videos, ( this is my first in fact) but i appreciate that there is someone out there that actually understands the how and why something works, on top of the
test and tune aspect of dialing in an engine.And not just "knowing" which parts to buy for a bolt on upgrade(s) This is the first video I've stumbled upon from Mr.V. and plan to check out more in the future. A little advice to all, there is almost always more going on in things than you imagine
I once seen a new valve design that had a 302 spin up to 14000 rpm, i doubt it is practical outside the lab, since I've heard nothing about it in recent years, but it goes to prove that just because something does not normally happen, does not mean it cannot happen
( and no that's not a typo, it was fourteen thousand RPMs)
th-cam.com/video/ow5cGV7bXCw/w-d-xo.html Old video of his. first comment has timestamps of subjects. Mostly mini engines,
Thanks David, I appreciate you live Sir
Take care, EM.
I've never been disappointed with a 30 seat, street and race car, if course it depends on the valve angle, my Olds 350 super stock heads flow well down low with a 45 because of the 6 degree valve angle, it made 580 horse and 514 torque at 9.33 compression, keep up the good work David!!!
@@Knucklehead4400 find some Batten heads that will accept 2.00 /1.625, valves , the aluminum version, spend 100 hours on the flow bench get the velocity where you need it the cam in your rpm range and you'll be there+6 cams ,3000 pound car has run 9.87, 132 mph in good air it's not easy, I had a Small Block Chevy that I worked on for 24 years I learned alot, the olds crosses the finish line at 8400, so much for the torque motor thing , it doesn't now what it is, I've said enough I can't give away all my secrets, follow David's advice and you will go fast my Olds freind
When I worked on link rod engines, it was for the the second bank, as the link changed TDC by a bit, somewhat noticeable on a 21" stroke. Cam overlap does make sense but I would do that in my head. Verifying lobe center is something I should be doing but haven't to date. When the injection pumps were shim adjusted for timing, the link side always needed that correction to carry their load. Have fun
Nice to have an EXPERT verify for me that most of the employees at the cam company do not know what they are talking about. I did hours of "homework" comparing dyno tests of different cams in engines with different heads and made my selection only to be told the cam I chose would never work. Unfortunately I took their advice enough to buy the next smaller cam which they also said was far too big and I was of course disappointed that it had LOADS of low end torque and ran out on me at the top end. Now that I have been properly educated about the cam timing I am anxious to see if there are gains for me to find with the cam i didn'twant. Thank you for the education 👍
Love the vids. Love the knowledge. I build my own engines on my mitsubishi and just acquired a 1275 mini im building also.
Awesome channel David
Gotta say David the Best Education i got from Any Motorsport has been tractor pulling . Been involved with NASCAR , Drag cars of many types , hydroplanes , motorcycles too . The Antique tractor pulling taught me more than all the others Scientifically . No comparison when you are on the level chaseing national championships from Any of the others . Effiency in fill and dynamic function is KING . Chase torque not horsepower !!! Only Formula 1 science exceeded it believe that or not . When you start twisting off 3 1/2 inch 4140 diameter axles case hardened with under 2000 rpm limits you begin to learn something that applies to All Enginnes .
I got a friend owning a highly tuned Mccormick 6 liter 6 cilinder turbo tractor. Flowed heads, reground cam, extreme rocker ratio , Holsett Hx82 with huge billet wheel ...producing 6000Nm @ 2400 rpm.... Thats what I call TORQUE....
In truck engines with 18 liters capacity with max rpm of 2900 the 10.000Nm barrier is simply crushed.....
Those low rpm engines are the most difficult as power band is so narrow : 2900 to 2000 ( depending on class , rpm limit and engine capacity) Sometimes its only 500 rpm..... Going lower lets sometimes rise TORQUE so much engines are literally torn apart!!!
I am building a 383 right now with Canfield heads ported to your specs and Lunati camshaft with your specs DV292 solid roller 11.0:1 compression. I cannot wait to fire it up!!
Great pointed video. Thank you. I’ve been considering a Lunati cam for a 414 sbc stroker build. Solid roller cam. 109 LSA but they say to install at 102. I thought that was quite odd.
Back in 1988 my dad had drawn a rotating valve train assembly he said getting rid of the up and down movement in the cylinder is the key to high horse power and long engine life
Some of the best information available! Please provide us with more advice on camshafts timing optimization .
Do you offer custom camshaft recommendations? And custom combo recommendations? Willing to pay for the advice.
Love the knowledge you give
Plane English explanations that are easy to understand. Luv it!
I read an article by you on how to build a flow bench with a vacuum cleaner. I cut a junk mopar 440 block in half and made one. On 1959 "509" performance heads I was able to get a 30% increase in flow by .150 lift just with my valve grinder! I went to 30deg seats and a multi angle seat and back cut the valves some. Later I installed 2.14" valves with the same style seats. About 35% better than stock. Those old 4 bolt valve cover heads are overlooked and most have really nice ports and chambers compared to newer 6 bolt ones.
Thanks for all the new uploads Mr. Vizard. Makes my day 100%.
I just stombled on to your video and I wached it and I was impressed with your explanation of the cam info I have subscribed to your video and I'm looking forward for more of your videos thanks for sharing this with us o the cam wheel is to determine the cam timing and to masure the over lap
Pure gold Dave. Thankyou.
What a great man. Thanks for sharing your knowledge
It would be total INSANITY to believe the timing recommendations for SBC, BBC, & SBF engines have only one setup each. All of these engines have too many head choices with such a wide array of chamber styles & shapes, valve sizes, & even valve stem angles for a single timing set up to take advantage of the design differences. Great video as always.
I can't speak to ford's manufacturer specs, but I can say that Chevrolet definitely does NOT have a 1 size fits all cam spec. Each engine package and option has a separate set of timing specs. In my Chilton manual for 1st-2nd generation Camaro's for instance, there is an entire chapter devoted to tables on what cam and ignition timing should be for each engine package, with each option, in each year. And it actually varies a LOT.
@@lochlanweichbrodt2852 We were not referring to factory specs nor intentions in regard to the camshaft timing. David said that the camshaft manufacturers (aftermarket), or at least some of them, have seemingly adopted a one size fits all approach to cam timing. I can also say that of the various listings in your Chilton manual, I wouldn't be surprised if some options were not listed. Most of the aftermarket manual printers either couldn't locate, weren't aware of, or chose to leave out some of the lesser known engine options if the manual has printed over 20 years newer than the engine. I know full well from first hand how many Ford specs were employed for the FE engine family. Cams were fairly easy to resource from the aftermarket for them in the mid 80s through the early 90s, but most other engine parts were not. I lost track of how many hours of research I put in combing through the factory manuals looking at combinations used before determining what parts to use for my F100. I was also lucky that the college I attended had a distributor machine complete with all of the spec cards for ignition timing curves, as well as the spring part #, for nearly every domestic engine option from 1960 through 1980. That was very helpful for setting up my distributor to run with the camshaft & piston choices. I also would add that if you use an aftermarket head, intake, & headers with even an entirely stock short block that you will gain power from changing the cam & ignition timing slightly to run with the other parts.
So true. The art of camshafts isn't about making maximum power, it's about understanding what the intended use is, knowing what different components of the cam do in the real world, how the components affect efficiency, and so on. Then it's about portraying this information to the public who wants to change their engine.
For example, a short stroke engine may respond well to at 204-210 cam on 114 LSA and 109 ICL for a person who just wants improved power everywhere, but not with max fuel economy. But a different person with the same engine might want max fuel economy in a heavier vehicle, and go to a 208-208 cam on a 110 LSA and 104 ICL, for max efficiency at low end. Both cams do similar things, but make an engine behave differently, and the owners may want something different. Add stroke to the equation, and they want different exhaust closing for the same purpose...
There certainly is not a onesizefitsall cam anywhere, and a good cam designer will show you how they react differently, without bashing other members with the same career path as they.....
Great video! Really enjoyed.
How to broaden the power band as much as possible?
Very well done. Thank you so much.
I always dial the cam in on a dyno, I often don't go for the highest power output but for most area under the power curve which is total horsepower. 'Sausage' HT Racing Thank you David, I hope you are well
I agree that peak power is rarely the best choice. Depends a lot on the usage too though, with a very high stall converter in a drag only application sometimes torque is significantly less important.
Who's dyno ?
Thanks a bunch Mr. Vizard!
Basically he's saying you need a 3/4 race cam..... And white New balance tennis shoes
i would say the inner wheel on the dial is for setting the crank and the outer is for setting the cam. and then you could then subtract the two number to then get your over all timing; would be my best guess on how they correspond to each other . and that is to help prevent valve slap, granted this is more then likely over simplified but is a general idea on what i am thinking :)
Excellent video David. Years ago I had to send a custom ground cam back to a cam manufacturer because they ground the cam differently to what I ordered. During the resultant phone, conversation, the knowledgeable individual told me that I didn't know what I needed, so they had sent me the cam that I needed. The first thing I asked him was what heads I was using, compression ratio etc. What transmission was in the car? and what diff ratio I was using? We then got onto tyres and vehicle usage. At the end of all of this he told me everything in my car was wrong, I told him everything was correct for what I was doing and his cam was wrong, so grind what I ordered and send it to me. Eventually I got the cam that I had ordered, delivered in a white box, and it did what I expected it too. Now I don't profess to have even a fraction of your knowledge, but I think that I knew more about selecting a cam that suited my requirements than the knowledgeable individual that I had been talking with. The guys that I was racing against were spending more money on their motors than I spent buying, and building my car, including the motor, and I got the trophies at the race meets, because they couldn't catch me. Now, in fairness to the knowledgeable individual, my combination was very unusual, and even today it is still unusual, but I was prepared to back my judgement on what I needed. What I really needed back then was the knowledge that you are sharing with us today. And I thank you for it. I'm really looking forward to your Ford videos, but I enjoy them all. Regards Greg
Thank you ...always something to learn...
Always wondered what that cam timing stuff was about. Wow how cool. When I get aluminum heads I'm definitely going to apply this knowledge.
the ford 460. after 72 was retarded 4-6 degrees, for fuel,crisis.. dished pistons, low comp, they went from 450 hp,,to 220.. i have a 351c., in an 82 bronco. it has 302c heads, std cam, 12.1 compression,, runs on lpg. damn fast..spins 35'' tires.. if i fitted a big cam,it,d be killing people..
@@harrywalker968 just fyi... that low compression 460 you mentioned, was not "rated" the way we do today. Even with those low comp heads and pistons, a stock 460 from the 70's will still pull 375 horses. Still not exactly an impressive horse-to-cube ratio, but a hell of a lot better than their supposed "220 horsepower." And the low-end grunt is still unreal.
He david your books, articles and videos had a huge impact on my tuning career which cumulated in building one of the most reliable and highest BHP engines in my country.
We won the National Championship in 4 rounds. Dr Neels Vanik and his engine simulation software also played a huge role in helping us simulate our engine. And exhaust.
Thank you. Very good information.
I'm a headquarter myself I learned it from the next Lincoln center I love your article right now awesome people don't understand about low and midlift numbers on a cylinder head for CFM they all want the big CFM number I
Grate information thanks for sharing all your wisdom.
It is a great honor and surprise to live while Vizard is still alive! And you have also differed strongly with the air filter industry earlier. But Iskendarian made strong text! Yes, the adv/ret would vary by the gearing and tranny of the car, also the carb size, tire size and weight of the car. You will have all these in mind.
Thank you!!! This is great info!!!
sorry for the educated guesses or I should uneducated guesses lol is it overlap or Flow? or maybe for an adjustable timing gear/chain I am just learning but least I'm learning from the Best thanks DV your the man God bless
External wheel is crank degrees of rotation, the inner is for cam degrees. Since cam degrees wheel is rated 60 to 120 degrees, I will guess it's for finding the lobe center line.
I've seen on TH-cam and first hand how being regiment in single component testing gives false feedback. I've seen a few head swaps (big one here is a 2V to 4V Cleveland) and it resulted in either loss or no gain in output. Myself, I ported and flow tested a little 5 valve Toyota 4AGE and lost torque below 6000rpm with an incremental increase above compared to stock, yet the flow bench gave a big improvement in low lift flow. The fault was the camshaft was no longer optimized for the new flow rate and discharge co-efficent. A better way to say it is "I had to learn the hard way" as I didn't optimized the cam to the new head flow. It wasn't until reading and understanding your books that corrective measures could be taken by installing a more suitable cam. At present this engine enjoys close to 1.3lb/ft per cu in, and best of all sees about 41mpg while still retaining the factory ECU. There are more tricks in your books I am meaning to try. At present, Im trying to complete a compression increase. Hopefully it shows promising results.
Very informative, thanks alot!
Great Title caught my eye,im subscribed.
Man I would love to work with this man for a couple of years.
We love you David!
Interesting to see deep dive in cam company theory. 🤔
Thank you for these videos. I just subscribed.
I suppose the second wheel is used for setting the position of the specific lobe in study and it works like one of those cardboard calculators for adding or substracting degrees
No not really.
Thank you much ! 😉😎👍👍👍
That was a brilliant explanation of the purpose of an adjustable cam drive and the difference in flow and advance/retard requirements depend and on valve seats etc. Decades of Vizard knowledge very evident, thanks!
Thank you for sharing this 👍👍
Thanks for the information.
Great video’s the best on TH-cam or anywhere else
What makes the concept of building and constantly improving the world of internal combustion engines is the fact that the final chapter will never be written. New products and ideas continue to push the envelope making a new engine build more challenging than the previous one.
Sir, i have bought many of your books, and followed your articles since the 70's. One data point missing in your lobe seperation angle tests has always been the intake centerline angle. If 108 lsa is ideal for a typical sbc, then lets test the intake centerline angle from 98 degrees to 114 degrees.
Kyle I use an adjustable drive to do a timing swing so as to find the optimum advance/retard.
@@marvingvx1 Thank You for all the hard work you have done to teach us Mr Vizard.
It's crazy but I've built so many small blocks that I can just listen and tell you when one has a tight lsa, they sound happy and crisp. Years ago I built a towing 454 chevy with ported oval ports and I had 3 cams ground for it, 110 108 106. Truck ran much better with the 106. Much better low end grunt and pulled harder and further on the top end even. Still have truck and engine today 25 years later
March 1967 I went to Ft. Knox, Kentucky for tracked vehicle mechanics school. I was in love with the AVSI-1790 gas V-12 engine. We had an awesome instructor. He was a staff sergeant . An E-6. And a local drag strip gear head. The Army tests EVERYTHING to the Nth degree. ‘He told us about this same stuff. The cam makes everything happen. Those words from so long ago in my mind was like a voice from heaven. My instructor was right. The Army was right.
In other classes in the Army, so many hot rodders or home schooled guys who love to hear themselves talk intelligently, really have no clue what those words really mean. In other words, they don’t know the difference between what body part they are sitting on, and a hole in the ground. Now, at almost 75 years old, and watching these TH-cam videos, I have to ask, “How come all the gear heads all have grey hair?”.
My dad died 22 years ago. Today he would be 102. The last few years I have realized how smart and wise he was. Just like the staff sergeant instructor I had back then. I was 19. Two things before I close this..........DONT LET THIS GREY HAIR FOOL YOU........AND OLD GUYS RULE. 🤠......young chicks don’t know what they are missing.😘
i need a high torque cam for a SBC 283 with vortex heads and beehive spring 1.6 rickers vr Jr intake, I saw a custom comp cam 112 duration at .050 and .480 lift. made great torque for a 383 magazine build.
Shhh……..you’re giving out some valuable secrets here.
It’s like magic when you figure it out.🏁
As allways something to think about.allways do my cam selection, following your recommendation out off your book makes sence to me.could you explain difference in timing to ci or volume of mixture.peace
Interesting test, giving up 20 lb ft of torque at 2500 to get 25 horsepower at the peak power, depends on what you’re doing with the car. Good test either way
Thanks for this video! I think I've finally started to understand cam events. I wish there were an infinitely adjustable cam drive for the inline Chevy 6. I think there might've been one at some time, but the best I can do now is multiple keyways for the crank sprocket. The camdrives I'm familiar with have a "straight up", an advanced, and a retarded keyway. I'm thinking it's gonna require cutting a new keyway when I decide on my cam.
I'll definitely build the head to optimize the low flow end of the valve events. After all, the Chevy smallblock isn't called a "belly-button" engine for nothing, and it'd be great to have something different. The head seems the best way to get the best out of 4.1 liters of low rpm engine. Especially one that seems optimized already for low rpm.
I'll be watching this one a few more times!
Thank you for sharing.
My guess on the degree wheel is, one dial is for cam degrees and the other is for crankshaft degrees.
David, when you are recording from your office, you are only capturing the left audio channel. I listen to your show through either headphones or stereo speakers in my shop. It makes for a large distraction. The other content recording of your show do get the left and right. I am a big fan of yours and have purchased several of your books. I think the recording fix should be easy to fix on a limited budget. I hope you can do that. Thanks for all you do.
TMc - yes - I think there is a problem with my camera. Plan on getting a big upgrade on that soon.
Experimenting is half the fun! It's also how you learn!
I used to mess around with Over head cam Lima 2.3,s I had 250 in take and 260 exhaust curation and a adustable pulley, I used to just spilt the over lap with the compression stroke at TDC, I ran 10 to compression on a non interfernce valve train and made 200 hp with headers and a four barrel
I had heard of porters going steeper than 45 seats for the sake of higher lift cams, but I have not run across 30 degree seats. Who/what application would benefit most from a 30 seat?
Overall, the overlap issue makes good sense: greater cylinder head efficiencies at lower lift means a risk of overscavenging calls for less overlap.
It's a Pontiac V8 Deal with Factory Cast Iron Heads used. Most of them use a 30 degree intake seat.
Like yourself I gave up on off the shelf cam grinds decades ago , I choose the lobes & lobe separation .
I also gave up on Comp cams , I have had far better results elsewhere .
Typically I have always built Mopar engines & the rod ratio also makes a huge difference in cam design as the piston stops @ TDC longer & moves away under pressure far more slowly with longer / higher rod ratio !
For example a small block Chev long rod is 6" & a stock 318 / 340 rod is 6.125 with a much taller deck height so with a shorter piston there is a lot more room to increase rod length leading to more efficient use of the fuel burned . I have also used a number of tricks to increase port flow & while gaining low lift flow .
Need to find your books and go back to school. Starting 5.2 mopar project.