4412 problems

[bmodracer]

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!!

[twisterf5]

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!!

are you sure it is carb. would check wire to coil / pick up or valves

[bmodracer]

Yes...changed carbs and all was good

[50j]

Float set too low? Small inlet fitting? Sat after being freshened or ran?

[bmodracer]

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!!

[ToddSmith16]

fuel line blockage.......filter in backwards? Line clear of debree? Needle and seat not working properly? Fuel pump pushing enough PSI?

[sj valley dave]

He said when he changed carburaters it ran fine. try calling the shop that freshened the carb and talk with them...

[500BOMBER]

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.

[DANNY]

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!!

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!

[fox1162002]

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.

[500BOMBER]

I'll give that 3.5 power valve a shot , and see what happens.

[26-62 racing]

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 26B

[26-62 racing]

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 26B

[26-62 racing]

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 26B

[bmodracer]

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 replacement

[let-r-eat]

Also check that your transfer slots aren't exposed to far. How far does your idle screw have the throttle blades open?Check to make sure fuel is squirting from the discharge nozzle when you move pump the butterflies.How far are your air adjustments turned out?

[26-62 racing]

Just a thought, you might want to wait on the different metering plate. That could just be a new problem to the whole process. Not trying to tell you what to do, but try and fix the problem first before you change anything. The new metering block could be better than sliced bread but if you install it and still have a problem with the carb. Then you are still at a loss for what is wrong.
Just my idea. Also let us know when you figure out what it is would help us all.
Thanks
Mike Bulpitt 26B

[dirtman45]

I agree with some of these posts, take it apart or have someone who has done these take it apart and make sure something simple isn't wrong. Spray carb cleaner though all the holes and make sure all the gaskets are put in the right direction.

Also, because this happened to me once, while it's apart make sure you take out the needle and seat to see if anything has got stuck in there. I did one once and had something from somewhere get stuck in the needle and hold it slightly open, it screwed everything up. I chased around all the problems that it didn't have only to find something stuck in the needle.

Let us know what you find out.