Holly Carb Jets

Harry · 06-20-2001, 08:59 PM

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

------------------
See my 1985 Mustang GT

BlackFly · 06-20-2001, 09:29 PM

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.

Five0 · 06-20-2001, 10:44 PM

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

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

Harry · 06-21-2001, 07:39 AM

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

------------------
See my 1985 Mustang GT

Harry · 06-21-2001, 08:30 AM

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

------------------
See my 1985 Mustang GT

jwboner · 06-22-2001, 01:02 AM

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.

Dark Knight · 06-22-2001, 10:25 AM

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

------------------
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 ;-)

06-20-2001, 08:59 PM	#1
Harry Registered Member Join Date: Oct 1998 Location: Dayton, OH USA Posts: 678	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 ------------------ See my 1985 Mustang GT

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
change jets or increase carb size	82 GT	Windsor Power	4	06-29-2004 07:30 PM
Holly Carb rebuild?	chico	Windsor Power	4	12-05-2002 02:09 PM
holly carb	john02b	Classic Mustangs	6	09-27-2002 07:55 AM
holly carb?	j's69stang	Classic Mustangs	6	05-29-2001 02:19 PM
Holly Carb 4150/4160	67fb390	Classic Mustangs	2	06-04-1999 11:55 PM

06-20-2001, 09:29 PM	#2
BlackFly Registered Member Join Date: Feb 2001 Location: winnipeg , manitoba , canada Posts: 83	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.

06-20-2001, 10:44 PM	#3
Five0 Registered Member Join Date: Apr 2000 Location: middleburg, fl, usa Posts: 1,134	I would agree with BlackFly. I had the same problem, and had it fixed. They changed the power valve. ------------------ James Cox nochevy@hotmail.com 1991 Mustang LX 12.565 @109.38mph 1.764 60ft

06-21-2001, 07:39 AM	#4
Harry Registered Member Join Date: Oct 1998 Location: Dayton, OH USA Posts: 678	OK, showing my lack of knowledge here, what's a power valve? ------------------ See my 1985 Mustang GT

06-21-2001, 08:30 AM	#5
Harry Registered Member Join Date: Oct 1998 Location: Dayton, OH USA Posts: 678	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 ------------------ See my 1985 Mustang GT

06-22-2001, 01:02 AM	#6
jwboner Registered Member Join Date: Jun 2001 Location: Under the hood Posts: 164	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.

06-22-2001, 10:25 AM	#7
Dark Knight Registered Member Join Date: Oct 1998 Location: Az Posts: 854	check the float level too... if it's high, it will run rich too ------------------ 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 ;-)