Anyone Degreed a LT1 Cam?

[JAKE]

This has been kicked around on another Forum for a few weeks now, and so far, I've only found two guys who've degreed-in their LT1 cam. I'm surprised that so few have done so, but that's an issue for another day.

For starters, I've degreed-in many, many camshafts over the years on both Big and Small block Chevys (so I know how to do it) and I have all the necessary equipment. But, I've never tackled a LT1 before, that is, I've never moved a LT1 cam from how it checked dot to dot.

Specifically, I degreed in the cam to verify the ICL hit according to the cam card specs, but, on a LT1, I never adjusted it any further..

Now, I'm planning to advance my son's CompCams shaft another 2 degrees from how I degreed it in when I installed his new cam several weeks ago. The issue that's arisen has to do with the IGNITION timing being altered at the same time - which I know happens when earlier engines with distributors (back of block) are the type being run. I plan to use an offset bushing installed in the camshaft gear

I'd like to hear from guys who have degreed-in their LT1 camshaft on engines running an Opti-Spark, to find out what, if any, steps were taken to address the Opti rotor movement issue.

Anyone ever degree-in and move their LT1 cam?

Thanks,

Jake

West Point ROCKS!

 

[Hib Halverson]

If you want to add 2° of cam advance, know that most off-shelf aftermarket cams are made with 4° advance in them already. If that's a case with COMP Cam you installed, you'd have a total of 6.

A Gen 2 V8 cam can be degreed just like any other SBV8 camshaft.

Because the ABITS runs off the camshaft--just by direct connection rather then a 90 degree gear drive--like Gen 1 SBV8s, cam advancing affects the engine mechanically in the same way, but....that's a little misleading because spark timing in a modern engine is indexed to crankshaft position not camshaft position so the ECM will compensate.

 

[JAKE]

If you want to add 2° of cam advance, know that most off-shelf aftermarket cams are made with 4° advance in them already. If that's a case with COMP Cam you installed, you'd have a total of 6.

A Gen 2 V8 cam can be degreed just like any other SBV8 camshaft.

Because the ABITS runs off the camshaft--just by direct connection rather then a 90 degree gear drive--like Gen 1 SBV8s, cam advancing affects the engine mechanically in the same way, but....that's a little misleading because spark timing in a modern engine is indexed to crankshaft position not camshaft position so the ECM will compensate.

That dove-tails into my thinking too; that ignition timing is referenced off crankshaft position and that moving the cam (advance or retard) is a mechanical change in the valve timing.

However, I wasn't sure how the PCM programming would be effected by the mechanical re-phasing of the camshaft's position. I didn't know for sure if the PCM would compensate or not.

Guys have told me I'd need to have the PCM re-programmed to compensate for the movement of the camshaft OR buy a MSD Opti which has provisions for adjusting the ignition timing.

Also, please break down 'ABITS" for me. I can't figure out what that stands for.

Thanks for your feed-back. I've been trying to gather detailed information to share with other Forum members on this. There's a lot of confusion on re-phasing the LT1 cam.

Jake

West Point ROCKS!