I assume this can be done but a question is how to confirm cylinder #1 is at EXACTLY TDC? I know you can line up dots on the timing chain but that can be off by a few degrees if eyeballing.

Thanks,
Ben

 

You can supplement that by removing the #1 spark plug and inserting a
thin, but long, screwdriver. Have an assistant turn the crank and watch
the marks, and at the same time, you hold the screwdriver and the piston
will push the screwdriver upwards.

When y'all notice the crank marks line up and you verify the screwdriver
indicates the piston at top, continue to turn the crank a bit more till you
feel the screwdriver going back down. Then, turn the crank the opposite
way until the screwdriver is at its top of travel, then compare that with
the marks.

I forgot to mention, the only way to EXACTLY know TDC is to remove the
driver's side head to observe the piston or drop the pan and observe the
crank/(#1) rod position.

 

the spark plugs on a lt1 go kind of sideways in the head so the piston wont push the screw driver up.

 

Lining it up is easy. You don't need to go through all that other trouble. It's been done this way by people for over 50 years.

 

Shoebox, I would always trust what you say.

Just to clarify, you are saying: "line up your dots by eyeballing and you will be always good to go".

I have no doubt you can get within a degree either way of EXACTLY TDC but is this good enough? Being off by that 1 or 2 degrees is not that big of a deal?

 

Exact TDC does not matter. If the crank dot is at 12 o'clock, you are good. Line up the dots and it will be right where it needs to be. Eyeball a plumb line straight down from the center of the cam face through the center of the crank nose, if you are concerned.

 

I've never had an issue with angled plugs - it's always been spot on.

 

If you dont mind spending $20 on a piston stop that you will use once every
ten years it's a good tool to find TDC with the heads on. This is also best
done with all the plugs out. Make sure you are on the compression stroke of
#1 and turn the crank each direction until it stops and make an index mark.
The center/middle of the index marks is TDC. All this is really not necessary
with an LT1 as stated above. Just put a couple of reference lines with a
permanent marker on the balancer and crank snout or block for reinstalling
the balancer. The dots on the timing gears will be very obvious, they are either
lined up or they are not.