Help me if you can

['80RegalT-type]

Ok, my motor has been rebuilt. Remanufactured carb, rebuilt turbo, forged pistons, stock cam, B&M 2800 rpm stall converter. My car loads up when given gas or put in gear. She bogs down and a fair amount of black smoke comes out, it seems worse when she's warm. When i give it gas she has very little power, i'm guessing from the richness of it all. She'll run ok in after 1500 rpm's but it seems the transition from idle to cruise there's a problem. I don't have my pecv hooked up (actually the alternative that pete came up with) but I'm not putting it into boost while i'm breaking the motor in so i'm not too worried right now. A little bit of fuel was comming out of port where the vac. line goes to the power valve. I'd hate to tear into that new carb but I might have to. I've checked vac. lines, used wd-40 to check for leaks. If anyone has any ideas of things to check feel free.

 

[b4black]

I think it's the lack of a PECV.

The carb's power valve is a normally open switch. The PECV provides a path for vacuum which sucks closed the power valve. Usually, when engine vacuum goes low, at higher RPMS or boost, the power valve opens up and richens the mixture. In your case, the valve is always open (no PECV to close it), and always very rich.

If you connect a vacuum line to the two ports on the carb where the PECV would connect to, it would closed the power valve at idle. But then you could run into situations of vacuum at the carb base while there is still boost at the intake (the reason for the PCEV in the first place).

 

[b4black]

My new EGR uses a external "transducer". It works just like the PECV valve except backward. One port is referenced to exhaust backpressure. It then allows vacuum to pass the other two ports when pressure > 0. You need a transducer that blocks vacuum when pressure > 0.


Or how about using the intake as the vacuum source instead of the carb base? I think Fred C. does it this way with a in-line check valve to keep the boost from blowing the valve.

 

['80RegalT-type]

well i tried hooking the pecv valve up to manifold vac. At first if i put the car in gear and gave it any gas it would die. So i turned the idle screws a quarter turn richer and that made a world of difference. No black smoke, more power. I'll work on getting my pecv system in, pete's diagram is kind of confusing me. Thanks for the help.

 

[Peter]

Rich is right . You need the PECV. Don't connect the powervalve directly to the manifold. The boost pressure will damage it.