I need a timing expert.
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From: mocksville nc
Car: '68 corvette '73 Corvette
Engine: 427 454
Transmission: TH400
I need a timing expert.
gw350 bottom end
compxe274
190cc heads
new e-curve dist.
holley 670
OK here is the mystery and this was happening with an hei dist too. After installing the cam and new timing chain my timing light shows it is firing at 45 degrees advanced. Now that i dropped in the e-curve, that is set on a 15degree start lockout with no vac hooked up, it is still showing that!!! It idles and revs great!!
I am 100% sure that the chain was lined up, 12:00 and 6:00 firing on #1 and set on 0. I am 100% sure the rotor was pointing to #1. 100% sure the light is on #1. I brought #1 up on compression and got it within 2-3 degrees of tdc.
When the timing light flashes the balancer mark is at about 10:00, 45 degrees
on the timing tape for an 8 inch balancer.
A car can not idle at that setting!!!!
Can anyone tell me what is going on????
thanks
compxe274
190cc heads
new e-curve dist.
holley 670
OK here is the mystery and this was happening with an hei dist too. After installing the cam and new timing chain my timing light shows it is firing at 45 degrees advanced. Now that i dropped in the e-curve, that is set on a 15degree start lockout with no vac hooked up, it is still showing that!!! It idles and revs great!!
I am 100% sure that the chain was lined up, 12:00 and 6:00 firing on #1 and set on 0. I am 100% sure the rotor was pointing to #1. 100% sure the light is on #1. I brought #1 up on compression and got it within 2-3 degrees of tdc.
When the timing light flashes the balancer mark is at about 10:00, 45 degrees
on the timing tape for an 8 inch balancer.
A car can not idle at that setting!!!!
Can anyone tell me what is going on????
thanks
Re: I need a timing expert.
Is your balancer designed to run with a 12:00 position timing tab or a 1:30 position timing tab?
Usually when thing are way outta whack you've got this kind of mismatch going on.
Most typical is a 1:30 position timing tab with a 12:00 position balancer. Everything looks like it's over-advanced by about 30* to get it to run right.
Or the outter ring of the balancer has slipped. Then who knows what it's going to read.
I ALWAYS mock up the balancer and timing pointer during assembly to make sure it indicates TDC when the #1 piston actually is at TDC.
Now that's it's assembled it's more difficult but not impossible. You can look through the plug hole and visually verify when the piston is at least NEAR TDC and see where your timing mark is in that position relative to the timing tab. If it's way outta whack you've found your problem.
Usually when thing are way outta whack you've got this kind of mismatch going on.
Most typical is a 1:30 position timing tab with a 12:00 position balancer. Everything looks like it's over-advanced by about 30* to get it to run right.
Or the outter ring of the balancer has slipped. Then who knows what it's going to read.
I ALWAYS mock up the balancer and timing pointer during assembly to make sure it indicates TDC when the #1 piston actually is at TDC.
Now that's it's assembled it's more difficult but not impossible. You can look through the plug hole and visually verify when the piston is at least NEAR TDC and see where your timing mark is in that position relative to the timing tab. If it's way outta whack you've found your problem.
Last edited by Damon; May 9, 2008 at 09:01 PM.
Thread Starter
Member
iTrader: (1)
Joined: Mar 2004
Posts: 404
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From: mocksville nc
Car: '68 corvette '73 Corvette
Engine: 427 454
Transmission: TH400
Re: I need a timing expert.
I marked the pointer when i put it at tdc and it is correct. It is a "1:30: balancer. I just can not figure it out???????
Supreme Member
Joined: Jul 2005
Posts: 1,675
Likes: 3
From: Arab, Alabama
Car: 1988 Trans Am GTA
Engine: 350 4BBL
Transmission: 700R4
Axle/Gears: 3.27
Re: I need a timing expert.
That is indeed a puzzler. If you verified TDC at the piston, with the balancer mark aligned with the tab, and 0° on the timing tape then there are only 3 answers.
1. The timing light. If it is a dialback light and something is wrong with the circuit inside it, this may be the problem. This may sound silly, but can you try a different light?
2. Are you using an MSD ignition system? It may be "fooling" the timing light.
3. You're not using a 300+ duration cam with a 106° lobe center that idles at say 1500 rpm are ya? Some of the full race setups require insane timing lead to idle at all.
1. The timing light. If it is a dialback light and something is wrong with the circuit inside it, this may be the problem. This may sound silly, but can you try a different light?
2. Are you using an MSD ignition system? It may be "fooling" the timing light.
3. You're not using a 300+ duration cam with a 106° lobe center that idles at say 1500 rpm are ya? Some of the full race setups require insane timing lead to idle at all.
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