Kurk78

so this past swap meet, i picked myself up a Proform 650 CFM carb with manual choke and mechanical secondaries. This is to replace my terrible 1406 Edelbrock carb that was vacuum secondaries and it gave too much hesitation when punching it.

so me and my dad got this carb thinking it would work out great. we started the car and it's getting way too much fuel and i have to hold the throttle down to get it to turn over. in the process, we ran out of fuel in a total of 20 minutes trying to tune it.

im asking for techniques in tuning these carbs because me and my father are scrating our heads and throwing fits trying to tune this stupid thing. anyone out there able to help?

blackbyrd

iTrader: (14)

broken jet tip?

Deguila

Hello, If I remember correctly these carbs are based on 4150 Holley platform. Have you checked float level in the bowls? If it backfired at any time in its life the power valve is probably blown. Been awhile since I messed with a carb, but used to run into this with 4150 a lot. Proform does have a tuning guide on line. Hope this helps.

Doug G

I would tear it down and find out whats in it so you have a starting point of where you are.

Float level
PV
Bad gasket

All could cause the issues you're having.

jimmyp3353

iTrader: (3)

Too much fuel where? Idle? Part throttle? WOT? Do you have a wideband? What's your FPR set to?

pantera_efi

iTrader: (1)

Hi Kurk, yes do the items check from the above "tech".

MY guess is that you will find the Metering Block Gaskets are damaged.

BUY JUST that gasket set (two of MB/Bowl gaskets) for much lower cost that a carb kit.

Test the Power Valve Diaphragm, I apply a "kiss" to this item after being cleaned.

Set the floats on the engine when in operation, I ALWAYS set the front bowl LOWER than the rear.

Lance