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4412 just freshened. Spits and sputters terrible after half throttle. Started with 75 jets and went all the way down to 69's with no change. Anyone got any ideas?
Thanks!!
Thanks!!
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are you sure it is carb. would check wire to coil / pick up or valvesOriginally posted by bmodracer View Post -
Yes...changed carbs and all was goodComment
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Float set too low? Small inlet fitting? Sat after being freshened or ran?Last edited by 50j; 01-22-2013, 10:29 PM.Comment
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I've adjusted the fuel level up and down with no change. I have #8 fitting into carb. It only sat about a month before using it. The only think I haven't looked at is the power valve. I highly doubt itvwould be bad. Its a 6.5 and the motor pulls about 11lb of vacuum.
Thanks!!Comment
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fuel line blockage.......filter in backwards? Line clear of debree? Needle and seat not working properly? Fuel pump pushing enough PSI?Comment
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He said when he changed carburaters it ran fine. try calling the shop that freshened the carb and talk with them...Comment
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I have a 4412 that does the same crap. I think they need removable air bleeds to fix it.
It seems to go ridiculously rich when the motor falls on its face. Leanin' down on the jets helps some,but creates lower speed running problems.Old enuf to know better, still too young to givadamm.Comment
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I have one that was having same issue rebuilt it with a 6.5 power valve and it was a load up nightmare restarts were a mess. I changed the power valve to 3.5 and it ran like a beast after!Originally posted by bmodracer View Post»»*†HÀ†§ HÓ††™««Comment
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Yes the 6.5 power valve is to big put a 3.5 in it also what size of motor do u have my 350 runs 80 size jets and my 406 has 85 same carb. Also check and make sure your squirter is spraying properly. Check your timing also.Comment
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I'll give that 3.5 power valve a shot , and see what happens.Old enuf to know better, still too young to givadamm.Comment
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The numbers on the power is when the valve will open at inches of engine vacuum. A 6.5 valve opens when in a wide open throttle position at 6.5 inches of manifold vacuum. A 3.5 valve opens when the manifold vacuum is at 3.5 inches of manifold vacuum. Their use is to to add more fuel through the carb in low manifold vacuum at wide open throttle. They will close as the manifold vacuum increases father down the straight away. Something has been missed in the rebuild causing the problem. Power valve loose allowing fuel to bypass the gasket. Fuel bowl or metering gasket backwards. Check ball missing under accelerator pump discharge nozzles. Which would cause excessive fuel to be pulled through discharge nozzles under certain throttle positions, causing an overly rich condition.
Mike Bulpitt 26BComment
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Reread you post, could you have an air or vacuum leak ? Some times when the carb spits and sputters we think it is to rich. Could be a vacuum leak causing a very lean condition. Check base plate gasket, check gasket between base plate and carb body for proper gasket and installed properly. If the carb did not have this problem before the rebuild, then something done in the rebuild caused the problem. Hope this helps.
Mike Bulpitt 26BComment
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Has the carb been properly cleaned. The fuel has to flow from the fuel bowl through the jets, through the metering block and exit through discharge tubes in the venturi. If the is dirt in the passage some where fuel flow could be restricted. If the air bleeds where not cleaned properly that would restrict flow also. Just giving more thoughts. Hope some of this helps
Mike Bulpitt 26BComment
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Thanks guys....I'm gonna double check everything is clear and mess with the power valve. Also thought about changing out the metering plat with a 500 Dorton replacementComment
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