scotts74birds

After installing a new intake and carb, 383engine, I have not been able to get the car running right, or at all sometimes. After removing the intake, suspecting a vacuum leak, I discovered that the left side heat riser was very oily and wet with gas. The oil in the pan and lifter valley is also diluted with fuel. First I realize that an intake leak will cause this. But, since the heat riser is blocked-off at the intake, why would it foul with fuel and oil? Do I have a possible problem in the head itself? Where does this passage lead? Please help!

scotts74birds

Like Noah's ark baby! but since I've bareley even gotten it to start, how can there be that much gas in it? It doesnt leak just sitting there but Would an intake or cylinder gasket let it int the heat crossover, how is it connected? My oil levels up about half a quart! But the float bowl is in the middle of the window?

Polara_68

buddy of mine had a similar problem years ago
on the corvette 327 in his '53 jeep cj..
turned out the person who had "rebuilt" the carb
had left out a jet! (damn drunken idiot)
His wouldn't start, as i recall,
but it did eventually blow hellified flames
about 3 feet outta the carb. impressive.
And just a few minutes of cranking dumped enough fuel
into the engine to raise the crankase level well over a quart.
I've also seen similar heavy flooding due to
dirt/debris blocking a needle & seat open..

scotts74birds

Thanks, I'll tear down the new carb tomorrow. Youre not the first person to suggest that there is debris in a new demon carb. Any clue why there is gas and oil in the heat riser on the left head? What does it connect to? Do I have a crack in the cylinder head?

Polara_68

Its late & i'm gettin tired (lol) but if I'm recalling correctly, the heat riser passage is nothing more than an exhaust crossover passage in the intake manifold (the hot exhaust gases heat the manifold plenum for better atomization and choke operation). Basically, I think you are seeing the raw fuel from the cylinders in that particular "exhaust passage"..
it's probably in the exhaust manifolds too..

scotts74birds

Yes it does cross the intake, but the new gasket blocks it off at the heads. So why is the gas and oil in the head part? Get some sleep. I'llBe around 2morrow if you get any inspirations. Thank You

BuckNeccid

Gas thru the intake, the combustion chamber, then out the exhaust valve, and enough back pressure and volume of gas to force some of it back into the exhaust crossover from the exhaust side. Can't really say why there's oil there as well, if they are used heads, could be it was washed loose by all the fresh gas.

scotts74birds

Aha! Now I see. Thank you very much. I'll start with re-sealing the intake and not worry about that. Appreciate the help everyone