Carb jet question.

Topic: Carb jet question. (Read 1265 times) previous topic - next topic

Carb jet question.

July 24, 2012, 05:15:25 PM

As you all know My motor is fairly stock aside from some bolt on goodies. I have a 600 holley on top of it. Ive beat my head against the wall trying to figure out what size jets to run in it.

I cant seem to get it right. I have a stockpile of jets from 58 up to 80. Ive tried almost every one of them. Still pig rich.

Anybody know off hand what the factory jet size for the pre 85 HO mustang is?

Carb jet question.

Reply #1 – July 24, 2012, 09:16:24 PM

Quote from: 87thunderbirdBlackJack;394849

I have a stockpile of jets from 58 up to 80. Ive tried almost every one of them.

Check to see if your power valve is blown

Carb jet question.

Reply #2 – July 24, 2012, 10:26:28 PM

Check the power valve to see if it is BLOWN as select one that is 2-3 sizes smaller than the vacuum you motor makes. But you said your engine is stock so a standard valve should be correct. Also make sure your fuel pressure is not over 7-8 and the float level is correct. You may be spilling over?? Also make sure you check the secondaries as well. As they can also richen the mix up. Look down the carb horn while it is idling. Is fuel dripping in??? also is the accelerator jets g in fuel at idle ?? All this has to be checked. Normally a 600 is not a rich running carb on a basically stock motor unless it has an issue. Also check the vacuum at idle and make sure the Power valve is the correct one and size for your idle vacuum readings !!

It has been a very long time since i messed with carbs. But i would think a base line primary jet would be app .059-.068. This is just from memory and that was a very ling time ago

Carb jet question.

Reply #3 – July 25, 2012, 10:18:51 AM

Well. Its a brand new carb. The origional jets in it were 65s. Its pulling good vacuum and the power valve is right. I'm going to adjust the accelerator pump and tweak it some more. It ran really decent with 62s so I'll start there and work my way up the food chain from there. Thanks for the insight its greatly appreciated.

Carb jet question.

Reply #4 – July 26, 2012, 09:56:34 AM

Holleys were known to blow the power valve if it back-fired just once, even if it was a little back-fire.

I had a 74' Grand Torino with a built 351w that ran 10.5 comp w/.588 lift & 284' dur . I ran a Holley 750 vac sec on it, but that carb was modified by me to have a secondary metering block w/idle metering adjustment screws. IIRC, the primaries were 68's & the secondaries were 72's. I also ran 2 early style O2 senors with 2 A/F gauges to help with the tuning. I didn't have a H or X-pipe installed.

I might just hi-jack my wifes car one weekend and come over to check out your ride

Carb jet question.

Reply #5 – July 26, 2012, 10:30:04 AM

Well, I havent messed with it yet. Ive got to get some of my 4x4 ford truck stuff sold.

I'd love to have ya check'er out. Shes still very rough though. got alot more work to do

Carb jet question.

Reply #6 – July 26, 2012, 08:03:53 PM

Bad Bird if his carb is new i would imagin he has the check valve protector in the carb for the power valve. Like i said it has been a long time ssince i tuned a carb. Thanks

Carb jet question.

Reply #7 – July 28, 2012, 10:05:49 AM

I put the 62s back in, and adjusted the floats and shes purrin like a kitten

Carb jet question.

Reply #8 – July 29, 2012, 07:19:35 PM

Quote from: TOM Renzo;394956

Bad Bird if his carb is new i would imagin he has the check valve protector in the carb for the power valve. Like i said it has been a long time ssince i tuned a carb. Thanks

Thanks for reminding me Tom, I'd forgotten that they (Holley) had addressed that problem. :D

Quote from: 87thunderbirdBlackJack;395033

I put the 62s back in, and adjusted the floats and shes purrin like a kitten

Glad you got it figured out! :D

Carb jet question.

Reply #9 – July 29, 2012, 10:27:06 PM

That is what i thought you were spilling over. Glad you got it fixed. NEXT ISSUE GUYS!!!! Just messing around Thanks