1986 corvette
Thread Starter
Racer
Joined: Sep 2002
Posts: 420
Likes: 1
From: SAN DIEGO CA
1986 corvette
I did a quick search on timing but couldnt find one so im sure im asking a question thats been asked a bunch.
Im setting the timing (or trying) and im having a hard time with the timing mark jumping all over the place.
I warmed up engine to operating temp and then dissconnected brown wire with black stripe. Engine changes sound. I put clamp around plug one and hooked up timing light (brand new Craftsman. I have a Snap on timing light coming today) I point light and the needle is all over the place like i never disconnected wire.
The engine is pretty new. I do have a mild cam in the engine and was wondering if thats causing the problem. The only thing thats not new is the distributor. That might be the original one from 1986 (i think) Ive had the car 13 years and dont remember changing it. Other than that the car sounds really good. I think the damper is original also.
383 stroker
dart pro heads aluminum
30 pound injectors
larger intake manifold
adjustable fpr
58mm throttle body
lingenfelter intake
racing aluminum radiator
3:54 gears
new auto tranny
Im setting the timing (or trying) and im having a hard time with the timing mark jumping all over the place.
I warmed up engine to operating temp and then dissconnected brown wire with black stripe. Engine changes sound. I put clamp around plug one and hooked up timing light (brand new Craftsman. I have a Snap on timing light coming today) I point light and the needle is all over the place like i never disconnected wire.
The engine is pretty new. I do have a mild cam in the engine and was wondering if thats causing the problem. The only thing thats not new is the distributor. That might be the original one from 1986 (i think) Ive had the car 13 years and dont remember changing it. Other than that the car sounds really good. I think the damper is original also.
383 stroker
dart pro heads aluminum
30 pound injectors
larger intake manifold
adjustable fpr
58mm throttle body
lingenfelter intake
racing aluminum radiator
3:54 gears
new auto tranny
Safety Car
Joined: Sep 2001
Posts: 4,134
Likes: 531
From: Glenbeulah Wi
How fast is the idle? Even though the timing connector is disconected the timing will jump up if the RPM is too fast. (Approximately above 1000 RPM) I have no idea why this happens but on my 1986 I need to make sure the idle RPM is low when setting the timing.
Thread Starter
Racer
Joined: Sep 2002
Posts: 420
Likes: 1
From: SAN DIEGO CA
Its about 800 to 900 rpm. The engine has a slight lope (looping idle) so i keep it up to stop it from stalling out when i come to a quick stop. I could try and bring it down and see if that helps.
Thread Starter
Racer
Joined: Sep 2002
Posts: 420
Likes: 1
From: SAN DIEGO CA
I changed timing lights to a Snap On brand and it worked perfectly. The timing mark stayed still. I wonder why the brand new Craftsman had so much trouble? Maybe i had a setting wrong or something on the Craftsman!
Thread Starter
Racer
Joined: Sep 2002
Posts: 420
Likes: 1
From: SAN DIEGO CA
I did have the chip reprogrammed years ago but im sure its time for a redo because of porting and larger injectors etc. I would like to find someone in San Diego that does dyno tuning and can burn a chip for me. As of now im just adjusting the idle manually to about 750-800 rpm.
Drifting
Joined: May 2013
Posts: 1,736
Likes: 31
From: Reno Nevada
The idle is set in the programming, and while adjusting throttle blade screw may make a temporary difference the ecm will always be trying to adjust back to the programmed value. Are you setting base timing to 6 degrees?
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Thread Starter
Racer
Joined: Sep 2002
Posts: 420
Likes: 1
From: SAN DIEGO CA
yea it was set 6 degree before TDC. I have no idea what was programmed for idle. When i find someone to do the dyno tune i will ask what the idle is set for. Im having trouble getting the car to stay on when its cold so thats why i adjust the throttle. whens its warm its fine. I might have to check the IAC to make sure it adjusted right. i just did the tps sensor check at .54
Race Director
Joined: Apr 2002
Posts: 10,036
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From: Anaheim CA