.045" for plugs with the HEI ignition system.
Plug gap
Thread Starter
Le Mans Master
Joined: Oct 2006
Posts: 6,388
Likes: 2
From: Eagle River Alaska
Plug gap
I know this is a dumb question, but what is the spark plug gap supposed to be on a stock 77 L-82 4 speed? I think mine is set too tight. I'm getting a lot of carbon build up on them.
Thread Starter
Le Mans Master
Joined: Oct 2006
Posts: 6,388
Likes: 2
From: Eagle River Alaska
So I guess now my question is, if the gap on the PLUGS is too close, will it cause them to carbon up, or is there a different issue?
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Drifting
Joined: Apr 2008
Posts: 1,305
Likes: 2
From: Lewisburg WV
thegazman
My 79, L-82's spark plugs are set at .045. I had trouble with fouling and discovered the carbuerator idle was set too rich. I leaned the idle out as much as I could and still maintain a good idle. This solved the problem.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Too close a gap could result in a lower spark energy and/or [certainly] a smaller spark length, which may cause missed ignition firings, poor mileage and low power output. Interestingly, too wide a gap can cause the same symptoms...but because there isn't enough spark energy to jump the widened gap.
Plug gap is a function of the level of spark energy available in the ignition system, primarily due to coil design. So, folks would do best to set their plug gap to what the maker of the ignition system recommends.
Plug gap is a function of the level of spark energy available in the ignition system, primarily due to coil design. So, folks would do best to set their plug gap to what the maker of the ignition system recommends.
Last edited by 7T1vette; Mar 8, 2010 at 08:20 PM.
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
No, a plug gap off by .010" won't cause carbon issues. Look elsewhere, mixture too rich, burning oil etc.
Thread Starter
Le Mans Master
Joined: Oct 2006
Posts: 6,388
Likes: 2
From: Eagle River Alaska
Its not using oil. I did have the carb rebuilt last spring. It could be set wrong. I'll look there, thanks.
Tech Contributor
Joined: Jun 2004
Posts: 20,952
Likes: 962
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Too close a gap could result in a lower spark energy and/or [certainly] a smaller spark length, which may cause missed ignition firings, poor mileage and low power output. Interestingly, too wide a gap can cause the same symptoms...but because there isn't enough spark energy to jump the widened gap.
Plug gap is a function of the level of spark energy available in the ignition system, primarily due to coil design. So, folks would do best to set their plug gap to what the maker of the ignition system recommends.
Plug gap is a function of the level of spark energy available in the ignition system, primarily due to coil design. So, folks would do best to set their plug gap to what the maker of the ignition system recommends.
I agree that going with the manufacturer's gap spec is the best default position.
.
Racer
Joined: Jan 2010
Posts: 348
Likes: 2
From: Lowell MA
Default for a condenser/point system is factory 35 point gap. Sometimes you have to play the game and wonder how safe the factory wants you to be with the car they built. Like setting total timing. My point gap is at 33. Yes, could effect low rpm performance but when that engine is reving and there is less time for that coil to charge and discharge, the closer gap helps that spark jump the gap. Also don't run resistor plugs and up the dwell a point or two for longer charge duration. Works for me. That was for guys w/o an HEI setup.
John
John
