I have been searching around for the proper way to degree an LT1 and have been coming up with mixed reviews, so and so says "the only reason to degree the cam is to verify the grind." Well so and so says "that isn't true and it must be degreed (by degreeing I actually mean setting the cam to specs with cam spacers or offset key ways)" With this being said, so and so said "if you actually degree it, it will throw off the ignition timing and injector timing."

I was thinking (just an idea), what if you set up your engine and find top dead center, install a pointer, and a timing tape (like you can get from jegs) on the crank pully set to zero.
-Verify how much off your cam is and then use a timing light to see how much off your ignition is.
-If I am right, if the cam is zero degrees off like it should be you should read 4* BTDC because that is the way the engine is manufactured.
-Now if the cam when installed and checked and it is say 3* advanced and you put a timing light on it, according to one arguement, you should still get the 4* BTDC, which in turn verifies that degreeing the cam has no effect on the ignition timing and if you do degree it you will have to make other changes to sync everything back up.
-But if you get 7* BTDC then the arguement that stands that if you properly degree it, it will effect ignition timing and that properly degreeing the cam is the right thing to do and that degreeing the cam to manufacture specs is actually sync'ing up timing and you don't need to adjust the computer when you properly degree your cam.

- I think I got that right ?? advance = BTDC/ retard = ATDC

I am looking for input on weather this idea will hold water or not.

 

Hopefully, that is the message I have conveyed in the past, cuz that is the position I maintain. If you (re)degree the cam to oem specs, when it was off, not only the cam will now come into sync, the ignition will as well, meaning it also, was not correct B4 degreeing the cam.

I think I got that right ?? advance = BTDC/ retard = ATDC

Ya, you got it right.

 

the only reason to degree a LT1 cam is to verify that it is ground correctly.....

 

As I understand things, when a cam says it has advance ground in, it is talking about cam (therefore valve) timing, not ignition.

IOW, when you compare the front of a cam that has no advance to one that does, the thing that is different is the clock position of the lobes in relation to the gear mount bolt holes and dowel pin.

On a regular SBC, you can advance/retard the cam all you want and not affect intial spark timing, because of the infinitely adjustable, rear mounted distributor. You just throw in the distributor and make the spark timing what you want.

On the LT1, moving the cam position (by degreeing) affects spark timing because the opti is mounted to the front of the cam and is not adjustable. The pcm uses the opti for reference positions for the cam and crank.

The pcm assumes the timing gears are oriented correctly (dot to dot), therefore it can track the crank position. If you shift the position of the cam in relation to the crank, you change initial spark timing mechanically (like turning the distributor to change timing on a SBC, only you are moving the cam instead of the distributor). Whatever spark timing is mechanically changed would need to be accounted for in the spark tables of the pcm.