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Pedja's 1968 Firebird

2019 March
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i need assistance with a New Proform 650 carb i've got

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i'm incredibly new to this carb tuning so i'd like to start with the fact that i have no idea what Jetting is and what a 'jet'does. does it regulate air? does it help the mixtures? 

my proform is pouring WAY too much fuel and i cant seem to sort it out. i'm talking 5 gallons of fuel in 20 minutes, idling. i opened it up and i cant get the billets off but i did find some odd numbers on what i think the 'jets' are. primary fuel bellow or barrel, whatever was .36 and the secondaries was .70

i think i just need understanding of these Jets

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While this first link is related to motorcycle engines,  but the terms and theories are sound and accurate.



How to re-jet a Rochester carb - parts I & II



Let us know if you have any other questions.

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Kirk Kirk, .36 & .70 really does not tell what size the jets are. So I can’t comment on how big they are. Different manufacturers use different designations for jets.This I will say this though, if you are truly putting 5 gallons in 20 minutes that engine, and I find that a little hard to conceive, as most nearly all engines would be flooded out. 

I ran a 600 hp. 302 Z/28 that got 6 miles to the gallon, 2 gallons in 15 minutes. I changes oil every 2000 miles because of concern about fuel dilution. So, be very careful! That much gas through that engine you will definitely ave fuel dilution and that can cause to very catastrophic occurrences. One wipe out a bearing because of poor viscosity or even worse a engine explosion! 

So please be careful! 

If you take a number drill set you can actually measure the diameter of the jets. Knowing this will help choose the jet for your application. You may actually have a bad power valve.

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