Top Dead Center
Tech Contributor
Joined: Aug 1999
Posts: 15,154
Likes: 3,959
From: Connecticut, USA
Re: Top Dead Center (ettev)
With the head on or off ?
With it on you can use a tool that screws into the spark plug hole that screws down on top ofthe piston. You have to be careful you don't crank it down too far and pop a hole in the top of your piston.
With the head off just use an indicator to find TDC and check it against the timing pointer. When I checked the L-82 in my 75 it was dead on the mark.
Gary
With it on you can use a tool that screws into the spark plug hole that screws down on top ofthe piston. You have to be careful you don't crank it down too far and pop a hole in the top of your piston.
With the head off just use an indicator to find TDC and check it against the timing pointer. When I checked the L-82 in my 75 it was dead on the mark.
Gary
Drifting
Joined: Jan 2002
Posts: 1,500
Likes: 0
From: N.Y
Re: Top Dead Center (gtr1999)
Take out #1 spark plug put your finger over the hole and have someone tap the key real quick. When your finger gets pushed out of the hole from compression that's it. Now line up the mark on the balancer with the indicator and you should be ok. It may be a good idea to disconnect the coil wire first just so it don't start.
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Re: Top Dead Center (gtr1999)
:iagree: with '99. To verify TDC takes a special tool for the spark plug and a degree wheel. It's really a full days job and needed only if you suspect your harmonic dampner has slipped. Instructions come with the cheap tool. Just be careful to rotate the engine slowly by hand so you don't bend the tool or put a hole in your piston.
If you just need to verify #1 TDC just pull your valves covers and line up the dampner is on 0*. Then check pushrods on #1 cyl - should be able to rotate by fingering but not move up or down (if adjusted correctly). And #6 cyl should be in overlap and pushrods should be too tight to rotate and rockers show valves opening. If #6 cyl rotate and #1 don't then your off by one crank rotation and need to turn the crank 360* for TDC on #1.
Hope this helps. :seeya
If you just need to verify #1 TDC just pull your valves covers and line up the dampner is on 0*. Then check pushrods on #1 cyl - should be able to rotate by fingering but not move up or down (if adjusted correctly). And #6 cyl should be in overlap and pushrods should be too tight to rotate and rockers show valves opening. If #6 cyl rotate and #1 don't then your off by one crank rotation and need to turn the crank 360* for TDC on #1.
Hope this helps. :seeya
Melting Slicks
Joined: Dec 2000
Posts: 3,407
Likes: 2
From: Carmichael CA
Re: Top Dead Center (ettev)
I would not recommend sticking your finger in any hole...it could get pinched by a valve...I've used a screw driver in the hole, but that may scratch the top of the piston or get wedged between a valve and it's seat.
The best way to determine TDC is with the timing marks...the notch on the harmonic balancer will line up with the 0º TDC mark on the timing tab extension from the timing cover. In addition to this you should pop the cap off of the distributor and line up the rotor so that it is pointing in the general direction of the #1 spark plug.
This method has the benefit of preserving body parts, engine parts, and does not open up any seals like the valve cover gasket where oil may leak out and get things dirty.
The best way to determine TDC is with the timing marks...the notch on the harmonic balancer will line up with the 0º TDC mark on the timing tab extension from the timing cover. In addition to this you should pop the cap off of the distributor and line up the rotor so that it is pointing in the general direction of the #1 spark plug.
This method has the benefit of preserving body parts, engine parts, and does not open up any seals like the valve cover gasket where oil may leak out and get things dirty.
Team Owner
Joined: Aug 1999
Posts: 42,487
Likes: 47
SPARTAN
CI 3-4-5-6-8-9-10 Vet
CI-9 AutoX Winner
CI-3 Go Kart Champ
St. Jude '03-'04-'05-'06-'07-'08-'09-'10-'11
Re: Top Dead Center (ettev)
What is it you're trying to do exactly? Any reason you can't use the timing mark and the orientation of the distributor rotor?
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer