Hi all,
My 46000 original mile 272 needed the original clutch replaced plus the distributor was froze in place so I pulled it out to freshen it. It was a grimy engine so one thing led to another and I tore it down completely.
The crank was turned 0.010/0.010 and all new bearings were installed. The water pump, timing chain, oil pump, and all gaskets replaced. The cylinder heads got a valve job and new stock duty springs. The cam was reground by Clay Smith to mimic a mild cam they do if they have cam blanks available. None were available at the time I called. It now has 272 degrees of duration on both intake and exhaust.
The cylinders were standard to + 0.003 so I just honed it and installed new cast rings.
The cam and engine were broke in with Royal Purple 10W30 break-in oil. It now has Valvoline 10W30 with a flat tappet cam additive.
When I run the engine at anything over idle or low rpms, like if I'm on the road, I get oil out the road draft tube in basically a steady stream. I can run out a quart in about 17 miles.
The road draft tube has no leaks on the outside. The drain tube is completely clear. The filter is brand new and seals against its saddle and the other end to the cover.
I did a compression check on the engine with the plugs out but not with the carb opened wide and the results were 95 to 105 with most at 100 psi.
It runs awesome. I had to relocate the road draft tube to the top position with a replacement valley pan and T-Bird tube to eliminate the oil issue. I have no noticeable blowby from the road draft tube in either the stock location or out the new location.
When I shut it down, only a little waft of vapors come out the oil fill, no different than what I've seen on any other healthy Y-block.
What am I missing? Anyone else see this issue?
Thanks,
Nick in WI

 

Did you ever find a solution to your oil leak. My 239 Y is doing the same thing. Thanks

 

df85732,
No I did not. One engine rebuilder in northern WI had the same issue at least a decade ago and he never found a solution. He suggested the valley pan mounted road draft tube to me as a solution.
After buying a block-off plate and the T-Bird replacement valley pan mounted road draft tube from Tee-Bird Products, I've had no loss of oil.
I won't switch it back to the low mounted version.
Drove as the mechanic/clean-up vehicle towing an aluminum Featherlite car hauler yesterday in an old car cruise. Had to haul a 1930 Model A back home after the ignition failed. My 55 performed flawlessly.
Nick in WI

 

Hi Nick,

Those compression numbers seem pretty low for an engine with the compression ratio that engine should have. You might run it again at WOT. 100 psi seems very low to me for a "rebuilt" engine!

Just had a look at my 57 Ford shop manual and for the 272, 292 and 312, it lists the compression pressure as a nominal 160 PSI at normal cranking speed......... 100 PSI or less, tells me there's possibly excessive blowby and excessive oil consumption.

Also, is the engine overfilled with oil? That could also be a problem if the oil is getting aerated.

Cheers,

Rick

 

Rick,
My Motor manual for the 55's 272 called out 130psi for stock cranking psi.
I'm running a cam with 272 degrees of duration on both intake and exhaust. 108 degrees of lobe separation angle. I attributed the lower cranking psi mostly to the overlap. At idle it has a slight lope and at hwy speed, it pulls like crazy (relative for a wagon with a small engine. Haha.) That never happened with the stock cam. It was all out of air at 60mph.
It now has about 750 miles on it and there's no smoke or oil use. With the 4.11:1 rear gears, stock size tires, and driving at 60mph, it's spinning some rpm's for sure.
The crankcase and oil filter full change took about 5.5 quarts- there's a spin-on oil filter adaptor installed. The dipstick and dipstick tube are both the original pieces. Having too much oil in the crankcase subsequently shouldn't be the problem. The windage tray on the upsloping side of the pan is still in place. There's no dents or damage to the pan.
It's a strange problem for sure.
Nick in WI

 

Perform a leak down test. 95 to 105 psi is really low for a rebuilt engine, no matter the cam used.

At 60mph, the engine should be around 2500-3000rpm.

Regarding the oil pan, assuming it is a truck pan, the pan with a "windage tray" is the heavy duty pan, which is a 7 quart system, 6 + 1 with a filter change. The normal pan is 6 quart, 5 + 1 with a filter change. So either way, you are under filled, and that certainly eliminates an over filled pan as the problem.