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Discussion Starter · #1 ·
subject says it all. i have a 2bbl Holley 500cfm on my 258. as you can imagine, its running alittle (alot) rich. need to take the jets down some and i am wondering where to start. any hints on what a 258 would need as far a jetting goes? thanks! matt

 

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Matt,
Goto the Holley website and email them the question. I did the same thing a couple of weeks ago. Tell them the engine, the carb and they can tell you what the right size would be.

Dan Stewart 1963 CJ5 "Caloosa Jeepers" member

 
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Please post the response you get.

I emailed them asking what Jets I should run in the 258, there answer was to check the color of the spark plugs and jet accordingly.

Not really the answer I was looking for but atleast they responded.

Jay C.

I know what you're thinking. Did he fire six shots or only five?
 
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Re: Please post the response you get.

Jetting a carb is not easy to do from far away...what size is in it now ? How rich is it ? fouling plugs, eyes wattering, smells bad, hydraulic lock-up, poor mileage ?
 
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The 500 cfm carb is meant for circle track racing. I would go with the 350 cfm two barrel. The smaller carb will be much easier to jet. Even a high revving 258 will never need 500 cfm. You will never be able to achieve proper fuel metering with that carb. But to answer your question: I believe the 500 comes with nubmer 73 jets.

 

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Discussion Starter · #7 ·
nenofury, you are right on! the carb is a left-over from my circle-track days. i bought the carb new from summit, threw it on, adjusted the float and idle mix, and went racin! never had a problem on the SBC 355. after selling the car, i had two extra holley 2300's. both almost new, stock jetting. so, for fun i thought i'd try putting one on a 258. it made a world of difference! so, i put the other one on my other 258 and made the same difference. now that summer is here, i want to drive the jeep more. only problem is i don't want to smell like rich exhaust all day. so, i just need a place to start with the jets. if i knew what they 2300's come with, i'll make sure not to get anything bigger. i will do the final tuning with the O2 sensor and a volt-meter. thanks! matt

 
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A few years ago I ordered a Holley 500 CFM from the Carb Shop in Calif, new, set up for a 258 and they sent it with #65 jets. It worked real good! It even worked well at higher altitutes.

 
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How about this carb...

How about this carb on a 304?

Jay C.

I know what you're thinking. Did he fire six shots or only five?
 
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While it doesn't answer your question, I purchased a new 350 cfm and it came with 61's. I since dropped to 59's and just a couple of weeks ago dropped again to 57's. Still happy with performance. With the 61 & 59s, guys following said I had considerable amount of black smoke when accelerating. Not so since I went with the 57's. John

 
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