Hi ALL!

My engine is a 355 carb chevy with HEI and as it was running two breathers I've decided to put a pcv valve on one side but I'm wondering if I need to set up again the carb and ignition??? At the same time I was removing the ECM harness now useless and hooked off the 12v on my choke and put another wire on but wirth some weak power when engine off... Now when I fire the engine it revs up and does not want to go down unless it gets hot and still does not go that much down... When I put on D the engine dies...

Any help welcome!!!!!!

 

Put it back the way it was. If your not worried about emmisions, the only thing the pcv valve does is run air back into your carb to burn the vapor again. essentialy you created a vacume leak. The wire to your choke needs to be 12 with the car on only.

 

its for emissions mostly.....depending on the motor, it isnt going to hurt anything, sucks the vapours out of the crankcase and mixes with the air fuel mixture.....Im runnind a complete crank case evac system, where the crank case fumes are sucked out via the exhaust pulse through the header collector....at high rpm this creates a negative pressure inside the block and helps with ring seal.....race only mind you....driving on the street I just unplug them. cars not a dialy driver and doesnt pass any smog tests, shes a permit queen.

 

No PCV valve = messy valve covers on a street-driven car.

Yes, it's a vacuum leak, but a small one. Your RPMs shouldn't change by more than 100-200 at the most. Suspect a faulty PCV valve if it changes by more.

You should not need to re-do your timing. However an modest idle speed adjustment and possibly a readjustment of the idle mixture screws is to be expected.

 

I agree with Damon. In addition, your choke may be faulty. What kind of carb is it? If a non-cc q-jet, look at replacing the choke thermostat. When you pump the gas and start it, it should cold idle at ~1400RPM or so, but if you blip the throttle (even after only 3 seconds), it should be able to drop down to 1000RPM or less.

 

The PCV valve is more than emissions. PCV valve on one cover, breather on the other is a better set-up for evacuating vapors (including moisture) than two breathers.