I started a topic a while back about my f100 with a 292 being hard to start and having major compression when the choke is pulled out but once you push the choke in it goes back to normal. I know a lot of you all mentioned the dizzy and adjusting the timing. I plan on it just haven't gotten the chance yet. However I pulled the dipstick today and there was a bit of fuel in the oil. I have replaced the entire bottom end. Bearings pistons and rings. So what could be causing fuel to get past the rings into the cylinder? I have already changed the oil once cause there was fuel in it. I thought it was just cause it was getting flooded. But would that cause it to get into the cylinder? Any advice would be apprieciated. Thanks

fuel pump diaphragm?
stuey

Is there a rebuild kit for them or do you need a while new pump

Sounds like your carb may be draining. Fuel can seep by rings into the pan when cold. Your comment on major compression kinda indicates this. An electric fuel pump and a bad seating float needle and seat may be your problem. If you don't have an electric pump your stock mechanical can be on the pressure stroke when you shut off and the fuel can enter the fuel bowl because of the bad needle and seat.

This is a little work but you can check this cold; before trying to start take out all the spark plugs and see if fuel runs out any chamber. Disconnect the coil and protect any thing from sparking and then turn over the engine with the key. If fuel flys out any of the spark plug holes you've got a draining carb. Good Luck 

56 Vic, B'Ville 200 MPH Club Member, So Cal.

I rebuilt the carb and it has a new needle and seat. Like I said it only seems to have major compression when the choke is closed. Does it do something inside the carb to send more fuel into the cylinder when the choke is closed?

Sorry not positive on what happens other than restricting the air for enrichment. Fuel can only get to your oil thru the carb. You say major compression when choke is pulled. I don't understand what you mean? It's hard to crank over with the choke pulled? Have you tried to start it by giving more fuel by pumping the carb a few times. For me that does the same as a choke with out using it.....good luck


56 Vic, B'Ville 200 MPH Club Member, So Cal.

I would imagine it is hard to start because of an ignition issue. If that is the case, once you are choking, cranking, pumping, etc, and you are not getting enough spark, weak spark, or a spark at the wrong time, then that fuel is seeping right past the rings - once the piston gets to the top of the compression stroke especially because the compression will push it past the rings (gasoline is obviously thinner in viscosity than oil).

Dry Lakes Racer is right about the drainage. These carbs tend to drain out when SITTING for any period of time. My take is today's fuel that has a chemical content/makeup that lets it seep past the old power valves pretty easily. I know I have had that problem in the past. 

"I know a lot of you all mentioned the dizzy and adjusting the timing. I plan on it just haven't gotten the chance yet." - you really need to do this here.


Daniel Jessup

Lancaster, California

aka "The Hot Rod Reverend"
check out the 1955 Ford Fairlane build at www.hotrodreverend.com

A bad mechanical fuel pump can leak fuel into the engine putting raw fuel into the oil.  If it is a fuel pump depending on what kind of pump you have, there are rebuild kits out there.  I rebuild a cheap used dual action fuel pump for a Y8 and installed it, it pumps up 5 PSI cranking (spec is 5 PSI @ 500 rpm idle) and it holds pressure.  Ive cracked open the hard line after sitting a few days and it still had pressure on the hard line.  The kit wasn't cheap how ever but I would not rebuild a fuel pump if it is not what is putting the fuel into the crankcase.


1956 Ford Fairlane Town Sedan - 292 Y8 - Ford-O-Matic - 155,000 mi

Yeah.  I would vote for the bad fuel pump.  If the fuel was getting into the engine through the carb, it would cause so much black smoke, you'd see it right away.  
If it was a little bit of fuel getting into the intake after shut-down, it wouldn't last long because the oil would still be hot.  The fuel would evaporate quickly.

The most common source of fuel in the oil  in marine gasoline (V-8/6/4 cyl) engines with engine mounted mechanical fuel pumps is via a leaking fuel pump diaphragm.  Since marine engines also have a transparent hose from the fuel pump case to the carb (air intake) , you see it right away when when you notice the engine running rich (like the choke is "stuck")

Automotive fuel pumps don't usually have the case mounted hose connection.


Cheers,

Rick




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1955 F-600/272/E4OD// Disclaimer: No animals were injured while test driving my F-600 except the ones I ran over intentionally!

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If the oil level is noticeably higher on the dipstick, then the fuel pump is a real consideration.  It’s not unusual for the fuel pump diaphragm to be leaking fuel to the crankcase while still supplying pressure to the carburetor so be sure to check that out.  The oil will need to be changed again if it has a significant amount of gasoline in it.

Lorena, Texas (South of Waco)