Holly Carb Jets
 

My car is running really rich. I swapped the plugs tonight and the old ones are really fouled (and they were only in for a month!). I am planning on going to a lower set of jets in the carb to help this. Currently it has a set of 65s in it. How low should I go? Or is there something else I should do instead to lean it out? If it helps, the carb is a Holley 80457, single pumper 600.

Thanks

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See my 1985 Mustang GT

after checking out your site, i see you have an "e" spec cam. your vaccuum has dropped significantly i would assume , therefore, have you changed your power valve yet? probably not ,huh! the factory valve installed in there is 6.5 in. of vaccuum. you should probably be using a 4.5 or 5.5 given your current level of idle vaccuum in gear . this should go a long way to using less fuel when driving normal, if you do that at all. as well as get rid of your rich condition. your 65 jets are not to big at all based on your engine specs, if anything a couple of sizes to small. the 65s are bone stock for virtually any v8 holley carb for stock replacement. hope this helps. good luck.

I would agree with BlackFly.
I had the same problem, and had it fixed. They changed the power valve.

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James Cox
nochevy@hotmail.com
1991 Mustang LX
12.565 @109.38mph 1.764 60ft

OK, showing my lack of knowledge here, what's a power valve?

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See my 1985 Mustang GT

OK, checked out the holley site and read up on power valves. I'll head to the parts store at lunch and see if I can pick one up. Will let you all know how it turns out.

Thanks

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See my 1985 Mustang GT

Your problem is probably the power valve, but you could still benefit in the adjust-a-jet I think they make a conversion kit to modifiy it to fit your application or may have made one to fit your carb directly, it's worth checking out to adjust jets while running to see what works best in about thirty minutes.

check the float level too... if it's high, it will run rich too

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84 convt,'95 302,AFR's, performer
3.55's, underdrives BBK shorties
stock cam, 1.7's
13.85@102.5
and a '68 stang that WAS nasty ;-)