[KGTO]

Been several years, never remembered having this much confusion (maybe I'm getting old, lol)

Cam is a Butler/Comp grind 068 HR

Usually I've used the ICL method to degree cams, so if you install it per the card won't the @.050 valve timing events be the same or at least close to what's on the card? Mine aren't. But ICL is correct, at least for 2 of the three ways I checked it.

ICL checked at .100" is 111, checked at .050" is 111, but at .020" was 108.75
ECL @ .050" is 120

Added and divided shows LSA per card at 115.5 (with the exception of the @.020)

When I check valve timing @.050" the card shows -5 BTDC which is confusing, does that actually imply "ATDC"? -6 ATDC would be BTDC?

I checked duration @.050" which was also odd. Exhaust was close at 223, but intake duration was 204.5. A far cry from 212.

Note: The spec for intake centerline wasn't on the card, but with 115 LSA and Comp usually grinds 4* advance I assumed 111 was correct. Unless that's my issue?

[KGTO]

Cam card for reference

[johnta1]

valve timing @.050" the card shows -5 BTDC which is confusing, does that actually imply "ATDC"? -6 ATDC would be BTDC?

Yes.

[Stan Weiss]

Originally Posted by KGTO

Been several years, never remembered having this much confusion (maybe I'm getting old, lol)

Cam is a Butler/Comp grind 068 HR

Usually I've used the ICL method to degree cams, so if you install it per the card won't the @.050 valve timing events be the same or at least close to what's on the card? Mine aren't. But ICL is correct, at least for 2 of the three ways I checked it.

ICL checked at .100" is 111, checked at .050" is 111, but at .020" was 108.75
ECL @ .050" is 120

Added and divided shows LSA per card at 115.5 (with the exception of the @.020)

When I check valve timing @.050" the card shows -5 BTDC which is confusing, does that actually imply "ATDC"? -6 ATDC would be BTDC?

I checked duration @.050" which was also odd. Exhaust was close at 223, but intake duration was 204.5. A far cry from 212.

Note: The spec for intake centerline wasn't on the card, but with 115 LSA and Comp usually grinds 4* advance I assumed 111 was correct. Unless that's my issue?

There is a very good chance that it is asymmetrical cam lobe. What that means, is if you check the ICL at a place other that where the card says it will not be correct.

Stan

[KGTO]

Thanks John! Since that's the case Intake Opening is way off, it was 8.5 BTDC

Stan, great point, I didn't even think about that, so that makes sense Thank you


I suppose the intake duration could be crappy grinding?


So I guess the main question is, do I leave it at the 111 ICL and not worry about the valve timing being different or move the events to match the card and see what ICL comes in at? Leaning that way to try it. Guess I should add, I have the 9 way Rollmaster set too.

[KGTO]

Hey all, I'm running the numbers on this cam card. If my math is correct the card is printed wrong. Is that possible?

[Formulas]

The first two engines i degreed despite my confidence i did them right at .050 they were wrong i used the mopar keys to adjust turned out one was retarded and the other advanced

The third one i did by ICL with a piston stop it met specs without any adjustment keys at all just dot to dot ( cloyes link chain )

[70GS455]

I ran into this issue also. The cam was non-symmetric. After calls to Bullet, it was discovered that the program they use to print the @0.050" events on the card assumed the profile was symmetric, regardless of whether it was symmetric or not. Their reasoning was that it was close enough. They had to go into the actual lobe file to manually look at the numbere to give to me and tell me what the actual 0.050 event numbers were. They were different from the card.

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[KGTO]

Thanks for the responses.

It took me a little while with the 9 way crank gear, but at 2* advanced things fell in line @.050. I also realized I was reading the timing events wrong which explains why half of them were correct. Still not sure why the intake duration @.050 is so far off but I plan to run through all the numbers one more time this evening and make sure it can be buttoned up.

[Stan Weiss]

Originally Posted by KGTO

Hey all, I'm running the numbers on this cam card. If my math is correct the card is printed wrong. Is that possible?

When I run the numbers it looks look that have the numbers for the intake and exhaust lobes reversed.

Stan

[Vid]

Cam cards misprinted? Nah, never…


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[70GS455]

Originally Posted by Vid

Cam cards misprinted? Nah, never…


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If that's a voodoo grind, I believe they check their advertised duration at some non-standard height. I seem to recall Harold saying something like it had to do with marketing

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[KGTO]

Hahaha!