Gentlemen,
IF you choose to "roll back the clock" , engine performce will STILL be very close to what it was with those "vintage" components. IF you "modernize" some of the components based on CURRENT knowledge , you will likely make MORE power than the vintage assembly. IF you don't you/we are doing something wrong! In the '60's Ford was VERY limited on their "own" cam profiles. Don Sullivan (rip) was a true pioneer in Ford camshaft development , but it is no secret the aftermarket was producing more powerful cams "at the time". The "D" cam lobe was designed around 150 gram intake valves and 7,000 RPM sustained use. "Sully" as he was known at Ford made at least TWENTY variants ( LSA/ timing advance , I have the SK notes to prove it) using the "D" lobe and one or two others. They were named E1,E2,E3,and E4. The D lobe was E2. What was sold to the public as C8AX 6250-D was the one Sully felt was best for "public" use. I am not sure "who" actually designed the lobes. At the time Ford was working with Harvey Crane , and they also had their own "in house" genius Don Tewles (later General Kinetics) using the Ford computer to design cams. It is also important to note that "some" Ford sponsored racers "claimed" to be running the D cam but were actually using an aftermarket cam. No surprise there.
Randy
Randy,
Thanks for all that old info.
1. So the hollow intake valves were 150 gram?
Would you know the weight on the factory stock 427MR intake valves?
2. When you say "7000 rpm sustained", does that imply the C8AX-D cam was developed mainly for 1968 NASCAR and perhaps NOT for the 1968 NHRA SS use?
I can see Ford stuffing it into the "135" SuperStock cars as it was the hottest FoMoCo cam they then had, and then could suggest that drivers not play with the engine. (Mopar did the opposite & just put the Street Hemi cam into their Race Hemis - knowing racers would change to their favorite cam anyway). But since it seems quite a few discovered that other solids ran .1 to .2 better (L1P1 Daytona, Crane 300-z8 and maybe even the F-266), wouldnt FoMoCo then point out that the "D" cam wasnt the optimum for NHRA, certainly not in the 428CJ?
Well I know this fiery thread is a year old but I'm still studying it - a lot more content than what the Federal Reserve is lying about right now - a few disagreements among different but knowledgeable people is how we ll learn. It's a classic thread.
I just weighed some valves I have on my Zieis cat-dieting-scale and got
133 gms 2.03 solid 3/8 intake valve OEM
135 gms 2.09 solid 3/8 intake valve TRW
So I'm concluding then that the C8AX-D cam was designed for 7000 sustained rpm and what must have been SOLID stem 2.19 intake valves at 150 gm each?
(The hollow stem EZ-pop valves were 100 gms each, right?)
I'd have thought NASCAR would want the hollow valves or weren't they up to lasting 500 or 600 miles?
