Thread: gassing out my oil pan

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Hi,
I have a high performance 454 engine and ever since i moved up to my 4000ft altitude ive had a problem with getting gas in my oil pan. I messed with the carb a bit and still had the problem and ended up switching to a 750 holley 4150 hp.After that i still had the same problem.

I then sent it in to a shop to make sure that all was right on it, and still have the same problem. When i was at sea level, i never had the problem.

Is there any other thing that could really be causing this? I have a post in shop talk about my vaccum advance, but right now i just have the vacuum canister plugged but debating to put a lock out kit on it or not becuase i dont have enough vacuum to use the vacuum advance.

thanx
david

What is the fuel pressure at the carb inlet?

last i checked i believe 5psi

Originally posted by daveid
last i checked i believe 5psi

bad fuel pump ??if this engine hase 5 ich vacuum i would look at the power valves in the holley i would think you need a 2.5 or 3.5 power valve in it and on the dist in would pin it and try to get the curve to come in as fast this you can all in before 2500 or try the base plate of the carb and see it it is more vacuum and try ajustable vacuum pull they sell them and it may be ajusted to pull it 5 ichs

Hi daveid, I have run into this a lot over the years (I'm at 4500), what I've found is that at this altitude the gas in the carb seems to expand a little bit more (especially after you shut the engine off and the carb has a chance to heat soak). This results in the carb flooding over.

The cure is simple, simply set the float level just slightly lower than the recommended level.

A couple of other tips if your interested:

At this altitude you do not have the air quality that you do at lower altitudes. The cars respond well to a step or two leaner jets and about 2 degrees more initial advance.

Actually you can go a little more on both the jetting and timing, but if you go on trips to lower altitudes very often you will find that too lean and have too much timing if you go beyond the 2 dregrees and 1 jet step.

That altitude does funny things to a carb!!! Back in the drag racing days we qualified for a Divisional Meet at Denver, never knew a car could run so bad!!!! One of the locals offered to help with the tune up, but even after that we were still more than a full tenth off our times at home in South Dakota!!!!!

Try a new fuel pump, the diaphragm is leaking gas into the crankcase.

well thanx guys for all the info. The fuel pump is only about a year old and has about 300 gallons of gas or so through it, so i hope its not that. The jets right now are at 73 primary and 84 secondaries. The power valve is at 4.5 which i had at 2.5 but the shop put in the 4.5. And no powervalve in the secondairies.

As for the altitude, Ya i hate it, This truck was built for me buy a friend/ dad type of figure and i moved a ways away so now im having to learn very fast. Never had any trouble with the darn thing until coming up to this altitude . lol. Im a rookie when it comes to all this. One more thing i forgot to say is i only drive like 8-10 miles and i get the smell of gas in the oil, and it starts to get a little thin.

Also, how would i check if its leaking in the crankcase?

thanx guys,
david

also too, does this sound like a carb problem like i think it is or is it sound more like an engine problem. When it was at sea level didnt have this problem, but i never checked the oil so i dont know for sure.

thanx,
david

hey dave check your fuel pump!! if you carb is that rich to thin the oil in just a short drive 8 - 10 miles you would have to be just about pumping gas out the tailpipe. you must be pumping raw gas down into the pan somehow. a fuel pump is a cheap easy fix and also the only way raw fuel can get down into the engine unless its literally running out of the carb
if the engine runs good and does not show signs of running rich i dont think the carbs the problem.

well does it matter how big the fuel pump is? cuz i think mine is a 280gph pump. Also, the engine seems to run great, i just hope it doesnt have to do with the engine. And the only way to check the fuel pump is to just replace it right?

thanx
david

i dont know of any way to check a fuel pump for fuel leakage but i guess someone out there has a idea. one could pressure it up and see if anything comes out the sseal but it may only leak if working on the engine.

thanx for the suggestion. my friend has my old fuel pump, i hope, and maybe could try putting that back on. Thats would be wierd though if that was the case cuz i never had this problem like i said, at least not that i know of at sea level.

thanx
david