Retard while cranking
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Melting Slicks
Joined: Dec 2005
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Retard while cranking
When using an electronic distributer from the early 1990's I know the timing is retarded while cranking , is there a set number of degrees that the module retards the timing or does it go all the way to zero in spite of initial timing?
Race Director
Joined: Mar 2006
Posts: 14,112
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From: Florida
That was only on certain hei modules (Cadillac I believe) and I think it was 10°. I know it was done because a super long advance curve was not reliable.
Or did it retard by vacuum too.
I can't remember, but I'll see if I can find it.
Module from an Olds 1980 350 is identical to the 4pin standard 990 module but has an aditional "R" terminal, which when grounded, retards the timing an aditional 10°. It was used with a vacuum switch on a fixed timing distributer. If you have an engine that needs a lot of advnce to run right and are having trouble starting it then this can be used in conjunction with a simple switch. Engines like this usually like timed vacuum advnce too.
Or did it retard by vacuum too.
I can't remember, but I'll see if I can find it.
Module from an Olds 1980 350 is identical to the 4pin standard 990 module but has an aditional "R" terminal, which when grounded, retards the timing an aditional 10°. It was used with a vacuum switch on a fixed timing distributer. If you have an engine that needs a lot of advnce to run right and are having trouble starting it then this can be used in conjunction with a simple switch. Engines like this usually like timed vacuum advnce too.
Last edited by noonie; Feb 2, 2007 at 09:37 PM. Reason: Amazing I found it.
I was thinking base timing was ignored while cranking (under 400 rpm) and retards "X" amount.
Race Director
Joined: Sep 1999
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From: Plano TX
The regular chevy 7 and 8 pin modules ignore the computer during cranking (under 400 rpm) and run whatever static timing you have it set at. The way most aftermarket EFI systems are setup, you dial in 10 dgr static on the distributor and then tell the EFI your static is 10 so it can command the advance properly.
Team Owner
Joined: Jul 1999
Posts: 65,492
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From: Orange Park Florida
The regular chevy 7 and 8 pin modules ignore the computer during cranking (under 400 rpm) and run whatever static timing you have it set at. The way most aftermarket EFI systems are setup, you dial in 10 dgr static on the distributor and then tell the EFI your static is 10 so it can command the advance properly.
