What are you guys running for non stock engines?

I'm using the stock AC R44TX plugs set @.060" gap for my 75 L-82 with HEI. The motors top end is made up of WP Sportsman 64 cc heads, flat top pistons,Xe268 cam, RPM intake,1.625 headers and 750 Speed Demon.

Thanks,
Gary

 

is most of your driving on the street??? track ?????

 

Street driving, with some 5500 shifts.

 

try stock or one colder, dry a few days and read

 

delco 46's i think

 

Cory why did you pick the 46's? What ignition are you using, points or aftermarket. It's Friday are you going to go out and get sheet faced again
Gary

 

That .060 gap seems a little wide unless you have a CD system. If that's a stock HEI I would think the spark would have trouble crossing the gap and you are misfiring without even knowing it at high RPM.

.045 might be more reasonable.

 

I'm running Crane XR-1 points conversion kit (electronic ignition)
and I think I'm stayin sober tonite.. I was trashed tuesday and wednesday nights, I ended up at the nudie bar on wednesday night and spent all my money for the rest of the week

 

.045 remember as they ware plugs open up

 

That's awesome! Someone I can relate to on the forum in a way other than simply C3 ownership. I would be out myself given a Friday night but hey I have two broken legs so what else can I do.

 

bench racing

 

ok you guys are saying go to .045 but the book calls for these plugs and gap? Except for Lars HEI kit, the distributor is stock.
Gary

 

What book? .060 is pretty darn radical. You know I think I remember reading that there was no improvement noted in any car when widening a gap over .050. But i can't remember where I read it so I would take that with a grain of salt.
It depends on compression as well, if you run a high compression engine I would tend to lower the gap a bit. You have flat top piston right? Take that under consideration.

 

I'm running the 35 gap and im not too stock

 

The books I referenced here are the 1976 edition of Chiltons,1976 edition of Clymer,1979 editon of arbooks 1966-1979 shop manual. All state .060" gap for '75 L-82, now the 1976 spec drops down to .045" 75 was the first year for HEI so maybe there was something different or Gm changed the spec after the first years use?

 

Guys, .060 was the original factory setting for HEI. Some Olds engines actually ran .080. HEI can easily handle gaps over .100. The wider gap was intended to help light off the very lean mixtures that were being run back then. I would retain the factory setting simply because it won't hurt anything, and it may help light things off if you encounter advers conditions.

Steve

 

Thanks Steve, is there a reason only 75 is listed at .060?
Gary

 

Gary, it's been too many years since I twisted wrenches for Chevrolet ('77 through '81). I don't have a good enough memory to tell you that answer. Lars might know. I do remember questioning a GM Training Center guy once about that .080 gap that Olds was using. He took me into a room where they had rigged a variable gap setup with 8 electrodes on an HEI and spun it up to around 5000 RPM. He then opened the gap up to 1 and 1/4 inches and it kept firing across all the gaps. Of course, that isn't the same as firing inside a cylinder under compression. But the points distributor on a similiar stand started misfiring around a 1/2 inch gap and died out completely by 3/4 inch.

I wouldn't hesitate to use the .060 gap at all. It gives a nice, big, fat spark with lots of fuel molecules to hit between the electrodes. If someone is only comfortable at .045, I'm sure there wouldn't be a problem. The HEI was developed for two reasons: to eliminate the wear factor of breaker points (they had to go 50,000 miles on emmission components) and to fire the wide gap necessary to light off those lean fuel mixtures back then.

Today's engines are so nearly perfect in the fuel mix department from combustion chamber, intake system and fuel injection design that the wide gaps aren't necessary any more.

Steve