Thread: carb conversion

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I want to use a 600 holly 1850 carb on a 4.3v6 I bought a holly conversion kit with smaller jets and power valve to convert it to 400cfm .I am concerned that I may need to retard the opening of the secondarie. Does anyone know how to do this or do I need to or am I wasting my time and money. Thanks for any help. .......Francis

Carefu lwith the jet dropping. Your venturi and throttle bores stay the same and you must maintain some simbalence of an air fuel ratio that won't lean it out. Tuning the secondaries for speed and amount of opening will be a greater help than anything. Use a vacuum gauge to do all the adjustments.

Originally Posted by francis blake

I want to use a 600 holly 1850 carb on a 4.3v6 I bought a holly conversion kit with smaller jets and power valve to convert it to 400cfm .I am concerned that I may need to retard the opening of the secondarie. Does anyone know how to do this or do I need to or am I wasting my time and money. Thanks for any help. .......Francis

Changing jets and power valve does not change the amount of CFM the carb flows, it only changes the amount of fuel going into the engine. Venturi, air horn, and throttle plate determine the size (CFM rating) of the carb....

Thats kind of what I thought but the guy at the auto parts said this was the way to go he was susposed to be an experienced carb guy From now on I will come here first thanks guys

Most counter kids are specialist in looking up parts on the computor, as long as you know what car it origionally came on, no custom mix match, and not old. (early '80's)

If he told you that, he's good for oil filters & wiper blades only!

Pat

As Pat said, lots of times today "experienced" means he's good with the computer and book learning part of it..... just no way the parts he sold you will change the flow rate of the carb....

I would suggest a 65 power valve and no larger than 62 jets to start with. I would also suggest the secondary spring kit to fine tune the secondaries.