Inliners International Forums General Discussion Engines Intake question on a 250

Okay guys I'm having a problem keeping my intake plugged when my car is running. I have a 250 motor and as you know there's two outlets. One of them i'm running my PCV valve, and the other one is plugged but for some reason when I'm driving or accelerate
the damn plastic plug comes out and then the car starts back firing and runs like hell. What's causing the plug to come out?
Is it because the plug is plastic and not strong enough to stay in? Please help.

Here's a picture of it. The red plug is the one I'm talking about.

It could be just a loose fiting plug/cap? No reason for it to come off other wise UMLESS the motor back fires befor hand.?

I think Twisted is right on both counts. You maybe running a bit lean, and getting some backfire that is not quite audible. Enough to blow a loose fitting cap off. Can you rev the engine when it is parked and blow the cap off? If not try retarding the timing a few degrees and see if it still does it. I have that problem with the carb on my 350, but none of the caps are loose. 8-]

btw What do the plugs look like? real clean?

Larry

yes, sometimes when I rev the engine while is parkerd it will push it out. I was thinking of the timing too.

If it is doing when parked, then I think your a little leaner than what retarding the spark will compensate for. Double check your timing in any case. The carb looks pretty clean, so I'm going to assume you put a kit in it, I could be wrong. 8-] Pull the top of the carb off and check your float and jet needle settings are correct. If they are correct raise the arm that holds needle about a 1/32.

Larry

Yes Larry, I put in a carb kit. I drove it again today for about an hour and it drives really good, but the moment I stop and turn off the car, that's when it starts spitting and it takes a few seconds to shut off completly. Then the plug comes shoots out from the intake.
Another question I have is: I noticed my oil pan was almost empty and I know I don't have a leak. Someone told me that is possible my mechanical fuel pump might be bad causing it to burn my oil.

The engine running on after you have turned the ignition of is dieseling. Dieseling is usually caused by hot carbon in the combustion chamber igniting the gas causing the run on. If the engine is burning oil it will build up carbon. I looked at your previous posts and you have indicated that that there was a blueish white smoke from the exhaust. Is the smoke continuous? Did you ever do a compression check?

A bad fuel pump could cause the engine to run lean. A bad fuel pump usually doesn't suck oil out of the crankcase, it pumps gas into the crankcase. I don't see that you have a PCV hooked up, so I wouldn't think your sucking oil out of crankcase. If it's not leaking oil, then it's sucking it pass the rings. How many miles do you get to a quart of oil?

What do the plugs look like? black and oily.

Larry

that's an old picture Larry, I do have a PCV hooked up. As far as the smoke goes, it did go away though. And yes, the car continues to run for a few seconds after I shut off the engine.
I going to go ahead and buy a new pump anyhow since it only costs $25 and see what happens. I have not done a compression check yet.
And to be honest, since I dropped the engine in there I have not driven the car for more than a couple of miles at a time. And that is a couple of miles in between weeks. I been doing things to the car so I haven't had the chance to drive it far.
So for the oil to be missing almost completly is weird.

I do not recommend using the red "plasitc" caps for vacuum plugs. Use rubber caps, and, if necessary, put a wire tie around it. When the engine compartment heats up the plastic caps turn mushy and manifold pulsations can blow them off.

Thanks, I will keep that in mind.