Gas getting into oil

[Wade]

Im fighting my back carb still, thought I had it fixed but I am still having the choke/nozzle getting stuck and not releasing back up. I have to manually reach down and push it up once warmed up. Due to this I believe I keep fouling out my plugs and keep getting gas into my oil. I start to get the gas odor and my valve cover breather starts smoking. I can smell the gas in the oil. I had this happen a while back and my oil was over a quart too high, so I drained it and put fresh oil in and cleaned up the plugs, then it happened again, did the same. Was fine for a few weeks and now I am having same issue. My question is, will the gas that is mixed into the oil work its way out on its own via evaporation or burning off if its not that much or do I need to change the oil again. If I understand it correctly, gas is not being burnt in cylinder and washing down the walls into the pan, would this even happen if my rings were in good order or do you think I have a ring problem? If rings were ok, shouldn't any excess gas in cylinder be blown out the exhaust? Thank you, trying to get a better understanding of this.

[MotoManMike]

This is a scary issue as it will wash your bearings out and ruin your engine if not resolved immedietly. Change your oil TWICE EVEN THREE TIMES!!! Run the engine a few minutes in between each change. Buy some cheap oil on sale somewhere as it doesn't have to be what you would normally run, you are simply using it to flush. Take your carbs off and check everything! Sounds like a float issue, carbs over full and letting fuel run down the intake runners prematurely. While you have them off clean and lube the nozzles and the sticking issue will be gone. I can't stress enough that this WILL ruin an engine. Not an issue you want to be riding around on figuring out. Gas is even thinner than water or oil and wreaks havoc on any bearing as it doesn't allow the oil to lubricate properly. I don't have first hand experience with it on a Z car but have seen this kind of issue trash $5k race engines on smaller machinery in a matter of minutes. Consider yourself warned. Check carb floats first, set float level. I've not seen a carb with proper float setting seep gas into an engine so mixture wouldn't be an issue from what I have seen. Even overyly rich carb settings wouldn't cause this kind of issue in my opinion and the car would run crappy I would think. I want you to take from this write up from me that you should not drive the car until you figure this out, whether i'm right on the reason or not gas in oil will ruin engines fast.

Edited March 22, 2012 by MotoManMike
spelling

[SteveJ]

If you have a mechanical fuel pump, the diaphragm can leak, letting gas into the oil. Remove the pump and inspect it. Be sure to replace the gasket if the pump is in good shape.

[Wade]

Its an electric pump. Ive been fighting this back carb for a while now. It has new nozzles and needles, all feels well when dropping the piston and the choke action when I have the box off and such, just when I start using the actual choke it starts getting hung up. My float is kind of tweaked a tad also where the metal hinge hooks onto it, but cant find any replacement so kind of have to deal with it, not even sure that is my problem, whenever I hook up the clear tubing to test the fuel level it looks fine but perhaps at times it is indeed getting stuck in the wrong position.

[Bruce Palmer]

If for some unkown reason you have fuel issues in the float bowl (too high) this might show up as gas dripping off the bottom of the nozzles because gas is pooling up on top of the nozzles. This would show up a fat running, gas smelling, plug fowling, cylinder wall washing. Could be too high fuel pressure, debris in the final filter (actually the needle and seat) hanging it open.

What size nozzles did you buy, .100" or .099"? We supply a lot of undersized nozzles to you rarified air types....

[Zed Head]

Its an electric pump.

You might have answered this already in some other thread, but is the pump a regulated low pressure pump suitable for your type of carburetor? I see that you have an L28, maybe it was swapped in with EFI and someone swapped the high pressure EFI pump over with it.

[Wade]

http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_Electric-Fuel-Pump-Airtex_5773407-P_52_R%7CGRPFUE2AMS_____#fragment-1

Thats the pump I got on it. I need to run to the store and get some oil, will check the actual pressure Im getting once back.

[LeonV]

That pump should work fine. Is your PCV system in proper working order?

[Wade]

Fuel pressure is steady 3psi. Checked pcv valve and all is well there. Think I got the stuck choke deal worked out, had to bend the arm that the nozzle connects too. When I had the domes off I turned the pump on to see if the fuel level was coming over the top of the nozzle tip and I didnt notice that happening. I reseated my needles to be flush with the lower ridge of the piston to give that a shot. Ive tried them on the upper ridge and also by just keeping them loose and setting the piston in and letting them adjust themselves (this way it was over the ridge about 2mm), in doing so I raised the knob for the nozzle to about 4 turns down. Was at 6 1/2 turns down before. Ill go back thru and resync the carbs and do that deal tomorrow and see what happens. I still smell the gas in the oil, hopefully its just leftover before the oil change and Ill change it again before running it much more. Just hoping the issue was simply the choke holding the nozzle all the way open, just wasnt even sure if that was the case if I should of been getting that much gas into the oil.