Fuel Mixed With Oil In Engine

Grumpy

Grumpy

The Grumpy Grease Monkey mechanical engineer.
Staff member
My friend with the 70 Z28 and carb problems has been interesting. I've had a hard time getting back over to help him with it since we got the Holley carb problems fixed. ie: wrong gaskets and bolts in the wrong holes etc. He told me his oil level was way high. I'm talking over a quart too high. He is meticulous about most things, so something was definitely wrong.
I went over last night and pulled the dip stick......... smelled more like gas than oil.
Crazy3.gif

I was able to light the dip stick on fire. by holding a Bic lighter on it for about 1 or so seconds.
I never knew that gas could get past the rings like that from a very leaky carb, but I guess it can.
He's going to drain the oil Sunday before we have a chance to fire it up again for setting the timing and advance and the fine tuning the idle mixture screws.
Does he need to drain the engine and flush it with clean oil then flush it again with and add new oil?
...or just replace the old oil with clean oil and a new filter? I was thinking Mobil 1 10/30.
Again, this is a 1970 11 to 1 350.
I'm hoping from running the engine and diagnosing the fuel issues the diluted oil hasn't hurt the bearings. We probably have put an hour on the
engine during the many attempts at diagnosing the carburetor problems. During that time, the fuel got into the oil pan.
Click to expand...

http://garage.grumpysperformance.co...ilter-you-sellect-does-make-a-differance.117/

yes, a close inspection of the oil filter is a darn good idea,
yes, you need a new oil filter and an oil change,
and yes you need to find and fix the problems source thats allowing fuel,
to get into the engine before proceeding any further.
yes, you may have caused excessive wear, on the bearing's, lifters cam lobes
etc if the diluted oil was run in the engine for very long.

be aware it's possible for a manual fuel pump to leak internally and slowly flood the engine with fuel in the oil.
I point that out simply because many people think the fuel might only come from a carb or injector related issue.
yes you stated it was the incorrectly assembled carb,
but others reading the thread may have not considered ,
the other possibility if they are having similar oil/fuel issues
 
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Pardon my snails pace getting back here Grumpy........ computer issues and budget issues don't mix well.:confused:
With the right gaskets and the plate screws in the correct position I think it's all fixed now. I may be a bit rich yet as I have the idle screws adjusted for highest idle. I know the screws are supposed to be turned in to drop a few RPMs. Just haven't done that yet. Jets are stock size and I have the secondary screw one full turn open. I read between .75 and one turn is where it should be.
Idle transfer slot is barely open and the car stars real nice with no backfiring. I dropped the initial timing down from 11 to 8 1/2 for the cruise since the vac can seems to be 20 degrees as checked using my dialback timing light. He doesn't have tape on the balancer, just a paint dab at 10 degrees. Vacuum is about 15 inches with the vacuum advance connected.
The car made the last summer cruise event without overheating and without a hitch. The cruise started 4 blocks from his house which was convenient.;)
His plugs are sooty so even tho the entire run time was idling at the cruise, his plugs are too cold. Cruise time was about 1 1/2 hours or more of slow going. He's using NGK V-power XR5 #R5674-7 plugs.
I emailed NGK for their stock plug equivalent and one step hotter and colder. I don't know where he came about using the plug number he's got now. Local parts store I guess.
The engine innards are stock LT1 stuff except for the WP Sportsman heads (stock ccs) with roller rockers. The heads are stamped 11.25. The car has MSD 6 ignition with nice heavy wires. It's got some full length coated Hooker headers with a crossover and 2 1/2 inch pipes and Flowmasters.
Thanks for adding this dilemma to the libraries of all libraries automotive.............. if the info isn't at Grumpies, it probably don't exist. :D
 
Thank you for doing what you do. It's barely run for the first time in a couple years, now almost time to put it away for the winter. Oh well. it's alive and running fine.
 
I once had a 350 chevy in a work truck. One day noticed the fuel gauge was falling faster than normal, ( it was heavy and got 5 mpg normally), Then it started to back fire every 5 miles or so. Got home, checked the oil and it was way over full! A gallon or so.
Fuel pump diaphragm had ruptured and fill the crankcase. It did not seem to have hurt it. But it didn't do it any good!
 
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