How often are cams messed up when you get them from the factory. I notices that when I got my cam XE236/242 the last 4 lobes are completely different than the others. Is that normal or should I be worried?

 

how different were they?

 

nevermind.... it was a mistake... the cam is fine

 

Degreeing a cam on an LT1 is an iffy subject, if you end up advancing the cam 4* say with the timing set you have to realize that you now have to take 4* of timing out on the whole table in the tune, and next and I do not know how much this really matters, but your injectors will pulse 4* ahead of time relative to the crank position at which they should pulse since the opti will move with the timing set, so most of the time it is best to just put the advantace/retard into the grind itself so you could install the cam straight up and not mess with the timing of the opti which controls fuel/ignition.

 

In case this was the original intent, the process of 'degreeing' in a cam is not intended to 'fix' a poorly ground cam, although some minor 'tweeking' of minor lobe differences can be done. If any of the cam lobes, or in the case of the LTx series of engine, drive dowel orientation, is not according to design specs, send it back for replacement. The intent/purpose, of the process, is to check (and correct if necessary) the orientation of the cam (timing) with the crankshaft. The cam/crank alignment is dependant on the 'linkage' between the two. Any misalignment brought into alignment, corrects and works WITH, not AGAINST the pcm. If the intent is to alter (IOW, advance or retard for specific tuning requirements) the cam timing, and thus the relationship between cam and crank from which it was intended/designed, that would be a separate/different issue.

 

Arnie said it, but in case it isn't clear: degreeing a cam is a checking/verification process. Advancing or retarding a cam is a tuning process which is performed using similar manuvers to "degreeing", hence the confusion. If you install an LT1 cam anything other than "straight up" (as verified by the degreeing process) the timing will be off and will need to be corrected.

Rich

 

To add to Rich's post, and to hopefully clear some air of confusion, potentially generated by above two posts; some oem, as well as aftermarket (CC, as an example) cams have advance designed into cam timing. To put it another way, when installed (or corrected) according to mfr., cam will already be in an advanced position. So, even though installed as oem designed/intended, which also implies opti drive dowel is in correct orientation, and consistant with what pcm has been programmed for, cam timing is in an advanced state. Do not confuse that advance, with the advance/retard example, in above post. It is very helpful, being familiar with LSA, and lobe CL, and how to determine whether cam timing is advanced or retarded, in understanding above statement. BTW Rich, smoking is not conducive to good health. :cough: :smurk: