Don Terrill’s Speed-Talk

One other thing that helps the GM cam work with the 10:1, is the longer seat duration. The seat duration on your Comp Cam is 260/268. The seat duration on the GM 602 Crate cam is 270/280. That means, even if both cams were on the same ICL, the intake on the GM cam would be closing 5 degrees later t...

One other thing that helps the GM cam work with the 10:1, is the longer seat duration. The seat duration on your Comp Cam is 260/268. The seat duration on the GM 602 Crate cam is 270/280. That means, even if both cams were on the same ICL, the intake on the GM cam would be closing 5 degrees later th...

If you put your cam on a 110 ICL, you're also putting it in on a 106 ECL
The 106 ECL will delay the exhaust valve opening, increasing cyl heat. It will also increase the exhaust duration past TDC, during overlap.

Sell the Comp cam, or keep it for another project, with lower compression. Buy a GM cam # 24502476, for around $150 new. 212/222 @.050", .435"/.460", 112 LSA https://www.gmperformancemotor.com/parts/24502476.html Installed on a 110 ICL, it will handle the 10:1 When you get done using the engine, you...

Here's a crazy idea. Have a cam made to fit the engine, not the other way around.

David Redszus wrote: ↑Thu Jan 14, 2021 2:49 pm May I ask, what is the cam lift and duration (after ramp) for the cam lobe shape you mentioned?

These are in the seat duration range on 288-304, with Lobe lift in the range of .352"-.377"
.842" diameter lifters

Depending on the specific lobe design, maximum lift typically occurs at about 72 CS degs after the end of the ramp. With our more aggressive EMV series flat tappet designs, we hit max velocity, around 50 crank degrees from the end of the lash ramp. The quicker it gets to max velocity, the longer it...

For those that want to understand the math, here's what we use. Lifter face Radius, minus .012"(safety margin), multiplied by .0174524064373(sin of 1 degree) = Max lifter velocity per degree. High School Trigonometry. :lol: Is it possible to use as little as a .008 safety margin? I have that writte...

Mike , .842 flat lifter still "around".0025/degree? It was when I was at Erson's in the '70s. I think you're mistaken. A max velocity of .0025" per degree, would only need a lifter diameter of .287" Using the equation above. .842" lifter has a radius of .421", minus .012" safety margin equals .409"...

For those that want to understand the math, here's what we use.
Lifter face Radius, minus .012"(safety margin), multiplied by .0174524064373(sin of 1 degree) = Max lifter velocity per degree.
High School Trigonometry.

Steve.k wrote: ↑Wed Jan 13, 2021 12:10 pm On a Ford size lifter is there a specific lift this starts at?

No. The flat tappet radius dictates the maximum velocity you can move the lifter, before the lobe runs off the edge of the lifter.
Where max velocity occurs, depends on the shape of the velocity curve.

A flat tappet set-up is "velocity" limited. A roller set-up is "acceleration" limited. The difference is, the lifter radius limits the velocity of the flat tappet, and there's no way around that. On a roller, it's the radius of the grinding wheel that limits the acceleration, and you can get around...

if I were to duplicate it and the only change being a roller (with more lift to suit the heads used), what would get changed? If anything. The overlap at 74 degrees (seat to seat) would remain the same. You are correct, you would use the same seat duration, if you don't want to change the rpm band....

Run these GM lifters
GM 12499225

learner1 wrote: ↑Sun Jan 10, 2021 2:20 pm How about a pro stock engine?

With a name like "learner1", you sure want a lot of answers given to you.