Engine popping? Help??

Possibly running lean or a vacuum leak? If it pop while idleing then might be an exhaust leak?

Easy way to find/test for a intake vacuum leak, is to turn in the idle set screw to achieve a 1,500 RPM "idle", then take a can of starting fluid & start spraying around the area where the intake gasket seals against the cylinder heads, if while spraying the idle/RPMS increases, you have an intake vacuum leak...Mark

Could also be crossed plug wires.

Ok great thanks will try all this evening. Will let yall know the out com

Ok checked wires all good. Timing is at 10 degrees. Its a brand new msd ready to run. The vacume line im using is on the front of the carb. The small out let on the power break valve(i guess what ud call it) on the manifold is open not plugged . Could that have anything to do with it? I dnt think im running lean. The pop is too consistent like every rotation of the motor when it hits the spot it popps. Possible burnt or stuck valve? It ran beautifully before i replace manifold and carb

If you have a open port that usually has a vacuum hose attached then it will lean out your fuel mixture and cause popping. Plug off that port and see what happens.

Well played with the carb a little. And it seems like the pop is gone.no bog on acceloration. Had a flame burst out of the carb. Buut just once. Any ideas? U guys rock!!!! Im a one man show yall helped alot

quote:

Originally posted by Bumblebee13:
...The small out let on the power break valve(i guess what ud call it) on the manifold is open not plugged . Could that have anything to do with it?..

No vacuum source should be open to the air. That needs to be plugged.

quote:

Originally posted by Bumblebee13:
Well played with the carb a little. And it seems like the pop is gone.no bog on acceloration. Had a flame burst out of the carb. Buut just once. Any ideas? U guys rock!!!! Im a one man show yall helped alot

When i used to run a 600 holley carb and left the car sit for a while (long enough for all the fuel to evaporate) the engine would pop and backfire quite a bit when i finally got around to starting it, then within a few minutes would settle down and be back to normal.

It was just the carb was completely empty and only some of the fuel circuits had fuel in them on startup (eg: idle circuit had fuel but secondary circuits were still dry) so a lean backfire would be the result when the throttle was moved open.

Once fuel had worked it's way right through the carb it was fine.

A temporary problem.


Yes, you should plug up any ports open to atmosphere, they will cause problems too !

Ok got it capped off. Will adjust the carb and timing as need be.. Is 10 degrees about right?

10 degrees
is what a stock 351c in a granada or car with an automatic trans is usually set at. The plate in my engine bay says 16 or 18% BTC so somewhere between 10 & 16 degrees is my guess as long as it does not start pinging or give you trouble at warm start up. Just got to play with the timming to see what your motor likes.