Need alittle input please.

This is my issue I have a 29 ford rat with chevy 283. While driving it cuts
out over bumps or even on cement freeway that is uneven, giving you up down motion. Things I have noticed eng. running very rich. I'm running 3 rochester 2bbl. progressive linkage with offie manifold.Have checked float level.Good. Inside of center main carb. has lots of soot/black in throat. And Carbs are fresh. Was wondering if anyone can tell if this early 57 283 should have a pcv valve. Keeping in mind offie manifold & valve covers have no breather holes, eng.block has breather fitting near dist. and oil tube at front of intake with vented cap. When veh. purchased it had a pcv valve between center carb. an block vent. Have eleminated ign. malfuncations.But I
am running early mallory dual point ign. with coil & external resistor.FYI.
Also have eliminated fuel delivery issue.Any suggestioned helpful.
Been banging my head on this one.

Cutting out over bumps I would say is an electrical problem, probably a bad connection or bad ground someplace. Do you have the road draft tube installed on the back of the block or is it plugged?

A while back I mentioned my daily driver Ford was cutting out on speed bumps and rubble strips. I finally found the problem when smoke started pouring out from under the hood one day. :eek: I had installed a marine battery (because I got those at cost at work) and it was slightly taller than the stock battery. On bumps it was touching the underside of the hood and momentarily shutting down the ignition.

My first thoughts on your problem was gas in the bowls being shaken down the carb throats (maybe too high a float level) but Dave might be on the right track with some electrical issue, like a ground.

Don

As Dave mentioned check your connections and be sure your starter connections are good and tight. If you're running an early GM solenoid it will have 3 connections, battery, run , and ignition and make sure they are tight. You might want to check the external resistor to make sure it's not burnt or cracked, in years past I've seen both.

Thank you for your input. Electrical was my first thought as well. But if
I mash the the throttle it will accelerate and start to clear itself. I'm
thinking carb's due to very rich condition. Ive never had 3 2bbl's before an
was told they are problematic. Is this true?
As far as my pcv question from center carb. to eng.block vent at rear by dist.should there be a pcv valve or just a hose from carb. to vent? Thanks again for your time and input. This is issue is a pain in my hind qtrs.

Had same problem in a Jeep with the battery jumping and grounding to the hood, also in an old stang where the ground wire was lose.

What is the fuel pressure at the carb inlet?

My fuel pressure is 5psi at spliter. 1 to 3 feed block. using vented aluminum
tank and rotory pump mounted at rear of veh. near tank pushing fuel.

Are the carbs the 2G or 2GC version...the 2GC is the larger version.. Years ago we were stuck using the Rochester 2bbls in circle track racing.. The best mod we ever found for them was buying the tapping tool to convert the jets from Rochester to Holley! Finally able to do some tuning on the buggers!! I think Speedway Motors might still sell one if jetting becomes an issue.

I would try a PCV valve in the breather tube--without one it's likely that crankcase pressure could be forcing a lot of oil vapor from the lifter valley through the center carb????