Tried to explain this to someone who just couldn't understand why cam lift was limited by the cam bore. You can only add so much to the top of the lobe before it won't fit in the block, and grind so much off of the base circle before the lifter is into the cam.
Me too, tried to explain it to somebody and he insisted I was wrong saying "no you can only change the lobe separation angle and duration" it's very easy to understand and this was a great explanation!
Just enlarge the cam tunnel, they have 60mm cam tunnels now with roller bearings for over 1” lift. Besides I would give up lift over duration on a cam to add power.
The other downside to this is the new profile is a lot harsher on your valvetrain overall due the abrubtness/steepness of profile transitions onto the rocker. Regrinds are ok if on a budget, but full-out builds should be custom cam off new billet.
Not an issue at low rpm but at higher rpms the the higher the rolling/sliding resistance. A smaller diameter has higher rolling/sliding resistance than a larger one.
All we run are regrinds. Never had any issues. I've been running my flat tappet since 95 with no issues. I haven't adjusted my valves in 20+ years and still running strong.
This works in this type of application with adjustable valvetrain. But there are special provisions that need to be made in order for it to work right, as demonstrated. This wouldn't be a good idea if there are no adjustments for the extra space created between the base circle and the valve stem. The picture shows that by taking material away it increases the gap between them. Which would make the opening and closing of the valve noisier. Since the lobe would be slapping the valve open instead of gliding along the profile as intended
But it's not so much that it's increasing the lift of the cam. It's just increasing the range of motion the pushrods move the rockers to open the valves. Basically changing the lift ratio of the rockers rather than the actual lift of the cam
You are correct 👍, you wouldn’t want to this to a engine that doesn’t have valve adjustments. You would need a longer pushrod to get your lifter preload back where it should be. 👍👍👍👍
I always used new hydraulic camshafts, heard of regrinds but couldn't make sense getting more lift. Now after this presentation I got it now, great info.
I'm sure I had that problem with a reground camshaft on a 1973 International 304 CID but there is no hydraulic valve adjustment the rocker arm shaft is torque down. Once done I had a tapping noise I was told I have to measure each push rod and have custom push rods made. What do you think?
Hopefully who ever did you cylinder heads set up your stem heights correctly and at least even. Use a straight edge on the valve stem tips and see if they are all the same height. If so you can check one cylinder/ lifter preload and pick a push rod and only need to buy a set. Much easier. You don’t want to buy 16 different pushrods.
Don't know how it came into my feed but I wondering how old school guys grinded higher lift cams I figured it had to do with the base circle. So what about duration?
I have a question. based off the diagram you made. Wouldn't there be no increase in lift. rather the lifter travels further down into the lifter bore. Right?
So its not that it actually lifts is higher its that it allows for more adjustment in the valve that the aduljustmet allows the valve to travle further.
If the cam has been reground the base circle is now lower and if it’s a non-adjustable valve train you need longer pushrods. If it’s adjustable then just adjusting the valves should get you back up and running. I always check my valve geometry and lifter preload when I build an engine.
Regrinding a cam does not automatically give it more lift. If you have a cam with .450 lift will not give it more lift. A .450 lift cam regroup with a .450 lift master the cam will have .450 lift. I had my roller cam reground because of bad lifter damage, I got back the exact same cam profile I sent in. TH-cam is famous for miss information.
No regrinding a cam doesn’t always make more lift. Think you missed the point of the video. It’s tough making videos to teach those that don’t know about engines and not offend people that do know stuff. That’s why I stopped making long video’s and about to stop short videos as well.
@@MrDanielSoliz It is implied by saying the valve opens further than normal but that doesn't take into account other things like the duration of the valve being open or the more pressure it takes to flip over a "paddle' compared to a gradual cam shape.
For all that regrinding, just by a new cam. You don't want any "downsides"! It totally changes the geometry, so now you have also created more "spring pressure" on the cheapy stock springs that will soon... You guessed it, give you another "downside". If you're trashing the engine, go ahead, regrind your bump stick...
@@MrDanielSoliz There are companies out there that will grind you, or make a custom cam just for your application. Another thing one can do is take your old cam n weld-up the lobes to "add" more material n regrind to stock or your specs, then have it hardened, nitrided etc, to beef it up! This "regrinding" IMO is a "last ditch" effort to keep the engine running. How long it will last is a crap shoot... 😳
I bet your not that old , 30 years or more ago you couldn't just buy a new cam , espically one you wanted with a specific grind ! Most speed shops would grind you your cam , and most hydraulic cams have built in ability to have reduced base circle , they are designed to have that ability ! That's how different factory cams are produced , they are all the same blank , just different base circles , hydraulic lifters will take up all but the most radical profiles , but even mechanical cams , just readjust . This has been used for 70 + years , from what I've seen , all these new cams delaminate so fast , cams from the 1960/70s you never saw a cam do that so often , one in 1000 cams maybe. I've always regrind my cams , I just look up a profile I need in some manufactures catalogue, take my used cam down and get that profile ground on it , it's heat treated and moly plasma coated , I get it back with a warranty and better than new . $65 or so max .
@@JosephCowen-fz8vj Go ahead and regrind your cams. That how they are made anyhow. Me? I prefer to make power with a moderate lift n increased duration for better cylinder fill to make power at the lower rpms. With more lift and/or more compression, yes, it will make power, however, that engine will have alot of parasitic losses. First, the engine is fighting to compress the mixture, second, the valve train is working harder to open the valves, ie, the pushrods are pushing harder against higher spring pressures. With a compression ratio between 9 n 10 to 1 compression, to run crappy pump gas, and a moderate lift cam, the engine will turn easier without fighting itself to make power. You will have an engine that produces good power n last a long time. Higher compression engines run hotter n do not last as long as lower compression engines. My motor is not a HP power house, but I'm happy with 400ft lbs of torque at 2500rpm! It pulls like a train n purrs like a cat at idle with a deep throaty rumble that rattles the windows... I like to make power between idle n 5000rpm where engines do the most work, not 6500+ rpm where engines have a higher chance of "blowing up"! My pockets aren't that deep... 🤔
@@Pork-Chopper I didn't understand a word of that , are you agreeing with me ? I didn't say anything about big cams , I'm talking cheap , cam suited to you specific application . The rest of your crazy rant had nothing to do with the post ..I believe you didn't comprehend the thread . What makes you think you can't get longer duration by regrinding ?? Your rant aggreeded with my point .
You adjust the valves with the lifters at the base circle of the cam. Smaller diameter base circle means a longer length adjustment, and when the lifter comes up on the lobe, that longer adjustment will push the valve further open.
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Great explanation! Thanks for teaching me something new!!!
Tried to explain this to someone who just couldn't understand why cam lift was limited by the cam bore.
You can only add so much to the top of the lobe before it won't fit in the block, and grind so much off of the base circle before the lifter is into the cam.
Me too, tried to explain it to somebody and he insisted I was wrong saying "no you can only change the lobe separation angle and duration" it's very easy to understand and this was a great explanation!
Just enlarge the cam tunnel, they have 60mm cam tunnels now with roller bearings for over 1” lift. Besides I would give up lift over duration on a cam to add power.
@@stevenbesson8988buddy that setup costs a lot. Most people can’t afford this and is not worth the cost.
Short version: lift is calculated with respect to lowest point on that crosssection of the cam. By grinding it down lower, the lift increases.
Yes sir! I do need to make a longer version of this. 👍
The other downside to this is the new profile is a lot harsher on your valvetrain overall due the abrubtness/steepness of profile transitions onto the rocker. Regrinds are ok if on a budget, but full-out builds should be custom cam off new billet.
Not an issue at low rpm but at higher rpms the the higher the rolling/sliding resistance. A smaller diameter has higher rolling/sliding resistance than a larger one.
All we run are regrinds. Never had any issues. I've been running my flat tappet since 95 with no issues. I haven't adjusted my valves in 20+ years and still running strong.
This works in this type of application with adjustable valvetrain. But there are special provisions that need to be made in order for it to work right, as demonstrated.
This wouldn't be a good idea if there are no adjustments for the extra space created between the base circle and the valve stem. The picture shows that by taking material away it increases the gap between them. Which would make the opening and closing of the valve noisier. Since the lobe would be slapping the valve open instead of gliding along the profile as intended
But it's not so much that it's increasing the lift of the cam. It's just increasing the range of motion the pushrods move the rockers to open the valves. Basically changing the lift ratio of the rockers rather than the actual lift of the cam
You are correct 👍, you wouldn’t want to this to a engine that doesn’t have valve adjustments. You would need a longer pushrod to get your lifter preload back where it should be. 👍👍👍👍
Simple math reduce the base circle size without adding material can gain you lift
Another question I had, answered! Thank you. I bought an untouched French Flathead and I'm virtually building it in my head and on paper first.
I have 2 reground cams done by Oregon Cam Grinders
I always used new hydraulic camshafts, heard of regrinds but couldn't make sense getting more lift. Now after this presentation I got it now, great info.
ah. that makes so much sense. i figured they welded more material on and did it that way.
I'm sure I had that problem with a reground camshaft on a 1973 International 304 CID but there is no hydraulic valve adjustment the rocker arm shaft is torque down. Once done I had a tapping noise I was told I have to measure each push rod and have custom push rods made. What do you think?
Hopefully who ever did you cylinder heads set up your stem heights correctly and at least even. Use a straight edge on the valve stem tips and see if they are all the same height. If so you can check one cylinder/ lifter preload and pick a push rod and only need to buy a set. Much easier. You don’t want to buy 16 different pushrods.
John-xe2lo I had that on a Oldsmobile with studs I just put a washer under the nut
Ahh yess. , sharper the point, more surface pressure.
The ,how many miles before wiping the cam lobes or mushrooming the lifters.
Don't know how it came into my feed but I wondering how old school guys grinded higher lift cams I figured it had to do with the base circle. So what about duration?
The base circle is lowered and WILL trash valve geometry if not careful
Cool info. This is true hot rodding
Base circle reduction
End of lesson
higher lift with less duration just doesn't make sense to me
I have a question. based off the diagram you made. Wouldn't there be no increase in lift. rather the lifter travels further down into the lifter bore. Right?
What happens when the lifter travels further down the lifter bore and you adjust your valves. When the cam spins the lifter will go up higher.
@@MrDanielSoliz 💡 I see now! Thank you for explaining that!
Question: would a .425” lift on a normal Flathead cam have lobes that are too tall to fit through the cam journals? Is this the reason?
Done this on 5hp flathead B/S engines and installed longer push rods
Increases side load, causes float sooner, and allows the lifter to hang out the bottom too far. Junk.
All aftermarket cams have reduced base circle diameter, not just regrinds.
So its not that it actually lifts is higher its that it allows for more adjustment in the valve that the aduljustmet allows the valve to travle further.
This kinda bothers just got 2.7 heads with re ground cams and it has hydraulic lifters and I hear bad things if it's out of adjustment
If the cam has been reground the base circle is now lower and if it’s a non-adjustable valve train you need longer pushrods. If it’s adjustable then just adjusting the valves should get you back up and running. I always check my valve geometry and lifter preload when I build an engine.
Wouldnt it have less duration too?
Regrinding a cam does not automatically give it more lift.
If you have a cam with .450 lift will not give it more lift. A .450 lift cam regroup with a .450 lift master the cam will have .450 lift.
I had my roller cam reground because of bad lifter damage, I got back the exact same cam profile I sent in.
TH-cam is famous for miss information.
No regrinding a cam doesn’t always make more lift. Think you missed the point of the video. It’s tough making videos to teach those that don’t know about engines and not offend people that do know stuff. That’s why I stopped making long video’s and about to stop short videos as well.
If it is so much better, why didn't the engineers at the factory think of that?
Why would you think a regrind cam is better and where did you hear that?
@@MrDanielSoliz It is implied by saying the valve opens further than normal but that doesn't take into account other things like the duration of the valve being open or the more pressure it takes to flip over a "paddle' compared to a gradual cam shape.
For all that regrinding, just by a new cam.
You don't want any "downsides"!
It totally changes the geometry, so now you have also created more "spring pressure" on the cheapy stock springs that will soon... You guessed it, give you another "downside".
If you're trashing the engine, go ahead, regrind your bump stick...
If you can buy a new cam, most definitely but they don’t make cams for a lot of older engines. In this case what would you do?
@@MrDanielSoliz
There are companies out there that will grind you, or make a custom cam just for your application.
Another thing one can do is take your old cam n weld-up the lobes to "add" more material n regrind to stock or your specs, then have it hardened, nitrided etc, to beef it up!
This "regrinding" IMO is a "last ditch" effort to keep the engine running. How long it will last is a crap shoot... 😳
I bet your not that old , 30 years or more ago you couldn't just buy a new cam , espically one you wanted with a specific grind ! Most speed shops would grind you your cam , and most hydraulic cams have built in ability to have reduced base circle , they are designed to have that ability ! That's how different factory cams are produced , they are all the same blank , just different base circles , hydraulic lifters will take up all but the most radical profiles , but even mechanical cams , just readjust . This has been used for 70 + years , from what I've seen , all these new cams delaminate so fast , cams from the 1960/70s you never saw a cam do that so often , one in 1000 cams maybe. I've always regrind my cams , I just look up a profile I need in some manufactures catalogue, take my used cam down and get that profile ground on it , it's heat treated and moly plasma coated , I get it back with a warranty and better than new . $65 or so max .
@@JosephCowen-fz8vj
Go ahead and regrind your cams. That how they are made anyhow.
Me? I prefer to make power with a moderate lift n increased duration for better cylinder fill to make power at the lower rpms. With more lift and/or more compression, yes, it will make power, however, that engine will have alot of parasitic losses. First, the engine is fighting to compress the mixture, second, the valve train is working harder to open the valves, ie, the pushrods are pushing harder against higher spring pressures. With a compression ratio between 9 n 10 to 1 compression, to run crappy pump gas, and a moderate lift cam, the engine will turn easier without fighting itself to make power. You will have an engine that produces good power n last a long time.
Higher compression engines run hotter n do
not last as long as lower compression engines.
My motor is not a HP power house, but I'm happy with 400ft lbs of torque at 2500rpm!
It pulls like a train n purrs like a cat at idle with a deep throaty rumble that rattles the windows... I like to make power between idle n 5000rpm where engines do the most work, not 6500+ rpm where engines have a higher chance of "blowing up"! My pockets aren't that deep... 🤔
@@Pork-Chopper I didn't understand a word of that , are you agreeing with me ? I didn't say anything about big cams , I'm talking cheap , cam suited to you specific application . The rest of your crazy rant had nothing to do with the post ..I believe you didn't comprehend the thread . What makes you think you can't get longer duration by regrinding ?? Your rant aggreeded with my point .
I’m not follow the logic here , grind off more material and adjust the valve . With that logic just adjust it with more material. What am I missing .
You adjust the valves with the lifters at the base circle of the cam. Smaller diameter base circle means a longer length adjustment, and when the lifter comes up on the lobe, that longer adjustment will push the valve further open.
We know how it does. We aren't stupid.
Who do you mean by we? Do you speak for everyone? I pose the question for those who don’t know.
Until you run out of heat treat ;-)
Just buy a new hi perf cam
Where can you get a new high-performance cam for a Studebaker?