350 stock engine - Team Camaro Tech
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post #1 of 6 (permalink) Old Aug 31st, 18, 08:47 AM Thread Starter
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Mitch
 
Join Date: Sep 2017
Location: Cedar City UT
Posts: 34
350 stock engine

Looking for recommendation on spark plugs. It does have Mallory electronic ignition.
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post #2 of 6 (permalink) Old Aug 31st, 18, 12:10 PM
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Dave
 
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Re: 350 stock engine

Brand preference is a personal choice. I like NGK and Champion plugs. AC-Delco used to be made by GM in 1962, but they bought Autolite or Champion plugs branded as AC plugs from 1963 on (Could be anyone making plugs and biding on the contract so it could be an NGK or Denso plug amongst others).

If you are looking for a recommendation for heat range use the recommended stock setting (45 on an AC plug), unless you are fouling the plug with oil, or it is acting like a glow plug. This is a good article covering information on heat range:

What heat range sparkplugs should I use?

The type of plug (5/8th hex tapered seat, or 13/16th washered seat depends upon the age of your heads. If you have ancient fuelie heads off of a 1957 283 they are worth their weight in gold to a Corvette owner restoring his car, but the point is it will use the older plug style. The factory went to 5/8th inch hex tapered seat plugs in 1971.

Spark plug gap depends upon the condition of your plug wires and the type of ignition you have (CD or induction). The more secondary voltage and the higher the amperage you generate the wider the gap can be to ignite the mix without blowing out the spark. Generally 0.038" for good wires and new points and condenser for an inductive ignition and 0.045" for a CD with a matching coil and well insulated plug wires.

Big Dave
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post #3 of 6 (permalink) Old Aug 31st, 18, 12:19 PM Thread Starter
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Mitch
 
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Location: Cedar City UT
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Re: 350 stock engine

Thanks Big Dave. Yes, I am having a slight problem with the engine dieseling. I'm pretty sure the heads are aluminum.
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post #4 of 6 (permalink) Old Aug 31st, 18, 12:38 PM
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Dave
 
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Re: 350 stock engine

Bet you have a lumpy rumpity-rump cam also. I will also wager that you have your throttle blades half way across your carbs transition slots (making for carb hesitation on take off) because of that cam.

The throttle plates being set too far open is allowing air and fuel to enter your engine and a very high static compression ratio is converting your car from the Otto cycle to a very inefficient Diesel cycle when you turn off the key.

Dieseling isn't a plug problem, but a carb problem.

Big Dave
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post #5 of 6 (permalink) Old Aug 31st, 18, 01:21 PM Thread Starter
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Mitch
 
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Location: Cedar City UT
Posts: 34
Re: 350 stock engine

From what I can tell without pulling the cam it appears to stock. No rumpy idle and no hesitation on take off. I have worked on adjusting the timing and bring the idle as low as I can. Will get it back on the road tomorrow and see if there's a difference. As far as the spark plugs go I was told that if the plugs were "hotter" than what is required it "could" add to a dieseling problem.
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post #6 of 6 (permalink) Old Aug 31st, 18, 01:56 PM
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Dave
 
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Re: 350 stock engine

Quote:
I was told that if the plugs were "hotter" than what is required it "could" add to a dieseling problem
A true statement! They can get hot enough to act like a diesel glow plug used to start a cold diesel engine.

Check out the article on heat range it shows a simple cigarette lighter heating a steel wire to incandescence. Now think of the caloric content (heat) generated by gas burning at 1,500F degrees. It can heat the ceramic and the center electrode hot enough to ignite your gas and air mixture as soon as the valve opens (causing a back fire). This is called preignition which is different from detonation, or dieseling. All can damage your engine.

Big Dave
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