4412 help

[keeter57]

Just built a brand new engine best of everything,we have to run a 2 barrel 4412 when we fired it and run it in we noticed smoke,not oil smoke fuel smoke.seems to be very rich it has 80 jets which is what we ran on our 383 and this engine is bigger(421)burns your eyes badly.I didnt know how low you can jet one but dropped to 75 jets and helped but still rich.We have ran this carb for 4 years,could it need something I am not doing?I will do whatever i need to do to solve this problem.

[twisterf5]

i would change the power valve sounds like it's bad.

[harris44]

What about your corner screws? Where are they set? To start you should take them in all the way and don't force them to bottom out and then back out 1 1/2 turns let it warm up and adjust them.

[keeter57]

What about your corner screws? Where are they set? To start you should take them in all the way and don't force them to bottom out and then back out 1 1/2 turns let it warm up and adjust them.

yea we did that -no change-what size pv would be good in this case?

[harris44]

Now when you adjusted them did you notices an increase or decrease in RPMS?

[Quickerthanu]

yea we did that -no change-what size pv would be good in this case?

I'd take out your power valve and see what part # it has on it. Should be one of the following: 65, 75 or 85 Hope that helps.

[keeter57]

I'd take out your power valve and see what part # it has on it. Should be one of the following: 65, 75 or 85 Hope that helps.

no change in idle until screws were all the way in,gonna get a new power valve,what size would be best ?

[Driver50x]

Changing the jets will not affect the mixture when the engine is at idle. If the engine backfires, it can rupture the diaphragm in a holly carb. That might be the problem you are having. The power valve number tells you the manifold vacuum when the valve opens. A 25 valve open at 2.5 inches of vacuum. A 75 valve opens at seven and a half inches of vacuum. To figure out which valve you need, Holly says to check what your vacuum is at idle, and then divide that number by two. A 65 power valve is pretty common in circle track engines. If you continue having problems with blown power valves, make sure there is a check ball installed in the throttle body vacuum passage to the power valve. The check ball helps protect the power valve during a back fire.

[keeter57]

Changing the jets will not affect the mixture when the engine is at idle. If the engine backfires, it can rupture the diaphragm in a holly carb. That might be the problem you are having. The power valve number tells you the manifold vacuum when the valve opens. A 25 valve open at 2.5 inches of vacuum. A 75 valve opens at seven and a half inches of vacuum. To figure out which valve you need, Holly says to check what your vacuum is at idle, and then divide that number by two. A 65 power valve is pretty common in circle track engines. If you continue having problems with blown power valves, make sure there is a check ball installed in the throttle body vacuum passage to the power valve. The check ball helps protect the power valve during a back fire.

Thanks guys Ill get it figured out now that i have a little better understanding of it all,just never have been a big carb guy,just put em on and go ! Well now its time to learn--

[keeter57]

Thanks guys Ill get it figured out now that i have a little better understanding of it all,just never have been a big carb guy,just put em on and go ! Well now its time to learn--

added a 6.0 pv set float level,still very rich,showing 9 lbs of fuel pressure,idle screws out 1 turn.really dont know what to do now any body got any ideas please chime in!!!

[twisterf5]

added a 6.0 pv set float level,still very rich,showing 9 lbs of fuel pressure,idle screws out 1 turn.really dont know what to do now any body got any ideas please chime in!!!

9 pounds is a bit high that is just max for a holly try dropping to 7/7-1/2 at idle

[keeter57]

9 pounds is a bit high that is just max for a holly try dropping to 7/7-1/2 at idle

So to do this i will have to get a regulator i guess,although i figured as long as no fuel runs out of the inspection hole while running it wasnt getting by the needle.but may not matter-not sure

[twisterf5]

So to do this i will have to get a regulator i guess,although i figured as long as no fuel runs out of the inspection hole while running it wasnt getting by the needle.but may not matter-not sure

one more thing to think about when going from 3.750 stroke to 3.875 383 to 421 you will have clearance problems and would most likely had to go to a small base cam in the 421 ??? is it degree in properly if not that could be all your problems.and timing ?? if your running 23 degree you need to be around 36 less degree heads less timing. this is what i would start thinking of .

[Driver50x]

Look inside the carb when the engine is idling. See if there is fuel dripping in. There should not be any dripping at idle. That will tell you if fuel is leaking past the needle and seat.

[keeter57]

Look inside the carb when the engine is idling. See if there is fuel dripping in. There should not be any dripping at idle. That will tell you if fuel is leaking past the needle and seat.

Well I checked the dist.and found the prob.My vac advance kock down had come loose and pickup coil was bouncing around also i went ahead and locked down the mech advance set timing at 36 smoke went away and engine runs totally different ,lots of response more crisp.I think that will solve it,thanks for all the help guys.i sure am glad we have this site it is really helpful sometimes.

[keeter57]

Well I checked the dist.and found the prob.My vac advance kock down had come loose and pickup coil was bouncing around also i went ahead and locked down the mech advance set timing at 36 smoke went away and engine runs totally different ,lots of response more crisp.I think that will solve it,thanks for all the help guys.i sure am glad we have this site it is really helpful sometimes.

well the carb is ok but still have smoke after running pulled off carb and there is oil in the intake the only way i know you can get that is intake gasket not sealing we changed gasket still doin it.anybody got any ideas,this is the same heads and intake we used on our other engine and no problems only thing different is the block.

[dirtman45]

Most likely your deck height on the new block is slightly different than the old one. So when you are tightening the intake down it is not really tightening to the head. I've also seen this happen last year to a friend of mine and his heads were angle milled in the intake surface was not machined at the right angle and the intake manifold would not mate up square. That one smoked bad.

Check the angles of the intake manifold surface and the head surface where they meet. You may also just need a thicker intake gasket if the deck height is slightly taller on the new one.

Just my thoughts.

[keeter57]

Most likely your deck height on the new block is slightly different than the old one. So when you are tightening the intake down it is not really tightening to the head. I've also seen this happen last year to a friend of mine and his heads were angle milled in the intake surface was not machined at the right angle and the intake manifold would not mate up square. That one smoked bad.

Check the angles of the intake manifold surface and the head surface where they meet. You may also just need a thicker intake gasket if the deck height is slightly taller on the new one.

Just my thoughts.

We changed gaskets went to thick ones with thin layer of rtv both sides let set overnite gonna crank this aft to see results.Cross your fingers

[billy5]

bigger engines increase air speed thru the small carb therefore it pulls more fuel thru jets faster...may need to jet down..also if your big engine needs more air to idle and you have to open the blades alot to get it to idle,then you are probably opening it past the idle circuit and its trying to idle from the booster signal...you will have to increase the idle hole size drilled thru the throttle blades.

[dirtman45]

We changed gaskets went to thick ones with thin layer of rtv both sides let set overnite gonna crank this aft to see results.Cross your fingers

Did it work?