Right spark plug gap made a big difference

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Dec 8, 2011 | 05:09 PM

Rick_V

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Joined: Jul 2011

Posts: 142

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From: Fort White Florida

Right spark plug gap made a big difference

I finally got around to replacing the plugs over the weekend. When I pulled the first plug it didn't look like it was supposed to and electrode looked like new but, when I checked the gap it was only 0.025. I replaced all the plugs with the new ones gapped at 0.035. All the old plugs had the same appearance and the same 0.025 gap. WOW what a difference in throttle response. I got the car in July and had chased a lot of things trying to figure out why throttle response was so crappy. Car as 270 cam in it and it has came to life with the new plugs (and correct gap). I plan to experiment with wider gaps to see if I can improve on it.

Dec 8, 2011 | 07:30 PM

Paul L

Team Owner

Joined: Aug 1999

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From: Ontario

Quote:

Originally Posted by Rick_V

You seem to have a 1979. Go with the GM/HEI-recommended 0.045". The 0.035" is for points cars.

Dec 8, 2011 | 08:51 PM

Rick_V

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From: Fort White Florida

Quote:

Originally Posted by paul 74

You seem to have a 1979. Go with the GM/HEI-recommended 0.045". The 0.035" is for points cars.

OK, still trying to figure out why the PO had em gapped at 0.025.

Dec 8, 2011 | 08:57 PM

pws69

Melting Slicks

Joined: Nov 2001

Posts: 2,668

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From: Eastern US XX

Don't spend too much time - they were just wrong and you will just be going backwards.

Nice job!

Quote:

Originally Posted by Rick_V

OK, still trying to figure out why the PO had em gapped at 0.025.

Dec 8, 2011 | 10:32 PM

jimboscarbs

Racer

Joined: Aug 2007

Posts: 267

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From: Springdale Arkansas

Plug Gap

Most SBC Dyno best with a healthy ignition from .032-.038 gap

Dec 8, 2011 | 10:40 PM

scottyp99

Le Mans Master

Joined: Mar 2008

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From: Oxford MA-----You just lost the game!!!!

Some people just screw 'em in there without checking the gap, .025" might just be what they were at out of the box. Don't worry about it, just get the gap set correctly. Like paul 74 says, HEI is .045", give it a try, let us know how it works out. Not sure what kind of experience level you are at, but if you are a novice, it's called super tuning, and it can sometimes make a noticeable difference, as you know. Next step is to optimize timing, if you haven't already.

http://forums.corvetteforum.com/c3-t...long-post.html

See ya!

Dec 9, 2011 | 07:43 AM

Rick_V

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Instructor

Joined: Jul 2011

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From: Fort White Florida

Quote:

Originally Posted by scottyp99

I am not a Novice but, not exactly a Pro I am somewhere in between. I had pretty much tuned it to optimum timing, jets etc. except for the plugs got a little lazy an didn't want to mess with them. I actually took the car out to Gainesville Raceway about a month ago for a test and tune. I just wanted to see what it would run. I only made one pass. It ran 13.55@101 mph with street tires and I lost a lot of first gear acceleration due to tire spin had a 2.03 60'.