floods on warm restart
 

I'm having a situation that is perplexing me. I'll mention the symptoms and then the facts as I know them.

Newer to me car, (less than 20 hours driving it), recently began flooding when warm. In order to start shortly (less than an hour) after driving I have to put accelerator pedal to floor when cranking to get it to start if engine is hot. It bucks and blows dark smoke for a bit then runs okay.

Engine: 489 BBC
Carb: BG Mighty Demon 850 float level set to middle of sight glass
Ignition: MSD 7AL, MSD Billet distributor and MSD coil
Electric inline fuel pump
Non-bypass pressure regulator set to 6 according to gauge on regulator
Recently installed new filler neck and reproduction SS gas cap
Initial timing 20 degrees
Idles 800
Temps steady at 208-210F
12 lbs vacuum at idle
Roller cam with 110 separation 236 duration
5 speed car

The car has been running very rich since I bought it. A few months ago I replaced the spark plugs which were fouled and the cap/rotor which looked corroded. Also I adjusted the valve "lash" because the valvetrain was so noisy. Several times I have adjusted the idle circuits to good results but the tune would go away.

Yesterday I removed the idle screws and blew the passages out and found much better idle quality after readjusting. (maybe there was debris?) I thought I had solved my problems until I took the car out. After parking the car for a couple of hours it was slow to start and produced a plume of black smoke.

From there I took a short trip and when I turned off the ignition the engine ran on and smoked out from under the hood. The car was off 30 minutes before restart and the car had a difficult time starting and staying running. I kept the engine revved for several seconds - pumping throttle- and it ran rough for a bit then smoothed out. It drove fine after that.

What can be causing this flooding or rich condition when I try to restart? Could the regulator and gauge be incorrect? Could the carb be the problem?

Thank you for any help you can provide. I'll take pictures if anyone wants to see the setup.

Jason, Modern fuels are to volatile for carburetors. They boil over easily out of the bowls. You are experiencing heat soak. A wood spacer and or/intake shroud will make a measurable difference. Lowering the float bowls a bit will also help. You are running a bit hotter than I'd like to see. 180-195 water temp will treat you better with a carb as well. I think your drivability issue is separate.

Thank you Todd. I'll order a spacer,heat shield, 180 thermostat, and insulation wrap for fuel line today.

This weekend I'll install and give an update.

Cheers!

It could come from your needle and seats leaking. We ran into a few years ago when running carbs. Are you running a return line? If not put one in between the carb and fuel regulator. What we saw was when running no return line . The fuel pressure would build up when the engine was not running and it would cause the seats to leak from heat soaking and flooding the engine making it hard starting. In the return line we also put a small aluminum plug in the line with a small hole in it so the it pump could keep up and not be all dumped back to the return line , so you could keep good pressure to you carb. This also helps the fuel moving to your tank so you have cooler fuel going to your carb.

Ditto on the spacer recommendation.

I had this problem with a 354 Hemi I put in my last project. A spacer under the carb solved it.

Parts ordered. Hope to install this weekend and report back.

Just reduce the cranking injector pulse rate...oh wait...LOL

Andrew

Don't rub it in. I'll join the 2000's soon enough. Fuel injection is in the long range plans.

All parts installed and so far so good in the garage at least. I haven't taken it out for a spin yet because air cleaner no longer fits.

Tomorrow I'll order a L88 air cleaner base from Classic Industries. It is supposed to provide a 2" drop. That will give me back almost exactly the 5/8" I lost by adding spacer and heat shield.

Thank you again for your support!

Test drive done. All is working well. Car starts after drive with little to no effort.

Thanks again!