Checking TDC on LT1
Thread Starter
Melting Slicks
Joined: Apr 1999
Posts: 2,521
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From: Windham, NH
Checking TDC on LT1
This may sound like a dumb question but how do you verify #1 Top Dead Center on an LT1? I am well versed in the older small block Chevys that have a timing mark on the balancer and a timing tab but the LT1 has neither. Is the mark on the hub supposed to point straight up or is there another way to find TDC exactly? I know that I have to remove #1 spark plug and turn engine over until I feel compression but how much further do I turn it without referance marks?
Drifting
Joined: May 2003
Posts: 1,730
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From: Charlotte NC
St. Jude Donor '05
Originally Posted by Jim Martley2
This may sound like a dumb question but how do you verify #1 Top Dead Center on an LT1? I am well versed in the older small block Chevys that have a timing mark on the balancer and a timing tab but the LT1 has neither. Is the mark on the hub supposed to point straight up or is there another way to find TDC exactly? I know that I have to remove #1 spark plug and turn engine over until I feel compression but how much further do I turn it without referance marks?
You'll have to find it by using a piston stop. Don't trust the hub as it isn't keyed so therefor theres no guarentee its on in the right position.
Safety Car
Joined: Feb 1999
Posts: 3,504
Likes: 4
From: Mexico Beach FL
Originally Posted by Alvin
You'll have to find it by using a piston stop. Don't trust the hub as it isn't keyed so therefor theres no guarentee its on in the right position.
It went something like this:
He could not find a reliable way to find TDC in aluminum heads with a piston stop because the spark plug hole axis is at almost a 90* angle to the cylinder axis. When the piston hits the piston stop, the piston stop is not rigid enough in aluminum heads for the accuracy needed -- in other words, it moves too much.
I suggested he find a dial-indicator with a very long tip that could reach into the spark plug hole far enough to touch the piston.
I never heard the end to the problem.
Tom Piper
