I've been gapping to .045 and not to .035. Which is correct? Which is better. Engine is stock everything. What are the REAL WORLD problems that i created in the process such as increaed potential for fouling, etc?

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1985 Z-28 305 TPI
215,000 mi. Original Eng.

 

Too large a gap will cause the spark to want to jump at the next easiest place, ie...any place where a plug wire may be real close to ground. This in turn will cause said wire to go bad in a hurry aside from the obvious misfire cond....
PS .045 should be fine

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bought a wrecked(head on,bad)'84 Z28 rebuilt it in'92 parked it in
'93 and ordered a '93 Z28. Got tired of the 4th gen in '99 and sold it and begin swapping in '85 TPI converted to speed density. engine is all stock except for comp cam. body has '86 IROC nose peice,ground fx and IROC wheels/goodyear 245/50's. IMO this car looks and feels more "racey" than my '93 did. and I love driving it. BTW fuel injection is great I'll never go back to carbs.

[This message has been edited by JAMES POLEDNA (edited July 23, 2000).]

 

My Haynes manual says yours should be gapped at .045. My question is why do the 85-87 engines get a different heat range than the 88 and later engines?

 

Yes.

Which one you use is probably right near about #101 on the list of the top 100 things that will change how your engine runs.

As far as the heat range, it's probably because fuel formulations changed right about then. Heat range is a "tuning" kind of thing anyway, it's not like your car won't run if you step up or down one range, or there's only ONE that's "right", regardless. ALOT of things affect what one would consider the "optimum" heat range for a given engine.