Mechanical Advance Issues
Thread Starter
Racer
Joined: Jun 2004
Posts: 322
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From: The Dirty, Dirty South
Mechanical Advance Issues
With all the timing issues on the forum lately I decided it might be a good idea to check on mine, especially since she ain't been running tip top lately.
So I checked and it was frozen full advanced. Not good. I un-froze the mech advance and cleaned everything and when I tested it I only get a maximum of 10 degrees mechanical befor it pegs out. I triple checked everything, nothing is binding, and it springs back great. I tested with the lightest springs in the kit. How can I increase the amount of mechanical advance? Shouldn't I be getting 20 degrees mechanical? Is there some bushing or other in there that limits it? I can manually move the advance until it pegs against the slots on the plate below the advance cam. It moves easily, too. Help!
So I checked and it was frozen full advanced. Not good. I un-froze the mech advance and cleaned everything and when I tested it I only get a maximum of 10 degrees mechanical befor it pegs out. I triple checked everything, nothing is binding, and it springs back great. I tested with the lightest springs in the kit. How can I increase the amount of mechanical advance? Shouldn't I be getting 20 degrees mechanical? Is there some bushing or other in there that limits it? I can manually move the advance until it pegs against the slots on the plate below the advance cam. It moves easily, too. Help!
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
what are the timing settings you are getting at base timing what is the degree/rpm and the degree/rpm where it pegs out? have the vacuum cannister disconnected for this test.
Thread Starter
Racer
Joined: Jun 2004
Posts: 322
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From: The Dirty, Dirty South
Originally Posted by bobs77vet
what are the timing settings you are getting at base timing what is the degree/rpm and the degree/rpm where it pegs out? have the vacuum cannister disconnected for this test.
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
Originally Posted by Contrail
I have it set for 16 degrees initial at about 750rpm. Total advance stops increasing at 2800 RPM at ~26 degrees with the vaccum disconected. I'm about 10 degrees short. I marked my balancer by measuring the circumference with a tape like the tailors use, then divided by 10 to find where 36 degrees would be, and I'm using that mark. At full advance it stays right at the 10 degree ATDC mark on the timing pointer. TDC should show as 36 advanced using that mark. With the vaccum can connected I get another 16 degrees for a total of 42. Anyway you slice it, I'm missing 10 degrees mechanical.
do it the other way....set timing to 36* at 2500-2800 rpm and then see what your degrees/rpm is at idle....the lightest springs will do exactly what you described they will bring in full advance early....so set the distributor timing for 36* at 2500 rpm and then check initial idle....you may be surprised to find the initial setting didn't change much.. you really should buy a dial back timing light you will not regret it...thenyou can actually measure the advance curve every 2*
Thread Starter
Racer
Joined: Jun 2004
Posts: 322
Likes: 0
From: The Dirty, Dirty South
Originally Posted by bobs77vet
do it the other way....set timing to 36* at 2500-2800 rpm and then see what your degrees/rpm is at idle....the lightest springs will do exactly what you described they will bring in full advance early....so set the distributor timing for 36* at 2500 rpm and then check initial idle....you may be surprised to find the initial setting didn't change much.. you really should buy a dial back timing light you will not regret it...thenyou can actually measure the advance curve every 2*
