gm targetmaster plug gap/timing?
Thread Starter
Racer
Joined: May 2000
Posts: 443
Likes: 3
From: Thurmont MD
gm targetmaster plug gap/timing?
I have a gm targetmaster engine casting (3970010-mexico engine) with 3991492 heads (70+lt1, camel hump, 64cc, angle plug). How can I find out the plug gap and timing for this engine.
I did pull existing plugs and they are anywhere from .35 to .45 gap?
thanks
Rick
I did pull existing plugs and they are anywhere from .35 to .45 gap?
thanks
Rick
Tech Contributor
Joined: Aug 1999
Posts: 14,373
Likes: 6,371
From: At my Bar drinking and wrenching in Lafayette Colorado
.035 gap is good for standard ignition systems. If you're running HEI or MSD, you can run gaps as wide as .045, but don't go bigger than that.
Timing is always 36 degrees total timing unless you have fast-burn style heads (in which case you can run about 32 total).
Timing is always 36 degrees total timing unless you have fast-burn style heads (in which case you can run about 32 total).
Tech Contributor
Joined: Aug 1999
Posts: 14,373
Likes: 6,371
From: At my Bar drinking and wrenching in Lafayette Colorado
rg -
Use a dial-back timing light set to 36 degrees. With vacuum advance hose disconnected, rev the engine until the centrifugal advance does not advance any further - get it pegged out. This will occur around 3500 rpm. At this point, the line on the harmonic balancer should line up with the "0" mark on the timing tab. Once set, hook up the vacuum advance and use the dial-back light to determine how much vacuum advance you're getting: you should be at 16 degrees or less vacuum advance.
For detailed instructions on setting up the timing, drop me an e-mail request for my timing paper to:
V8FastCars@msn.com
This describes how you can do this operation without a dial-back timing light if you don't have access to one.
Use a dial-back timing light set to 36 degrees. With vacuum advance hose disconnected, rev the engine until the centrifugal advance does not advance any further - get it pegged out. This will occur around 3500 rpm. At this point, the line on the harmonic balancer should line up with the "0" mark on the timing tab. Once set, hook up the vacuum advance and use the dial-back light to determine how much vacuum advance you're getting: you should be at 16 degrees or less vacuum advance.
For detailed instructions on setting up the timing, drop me an e-mail request for my timing paper to:
V8FastCars@msn.com
This describes how you can do this operation without a dial-back timing light if you don't have access to one.
