1972 911 Oil Starvation question

JB · 10-12-2004, 03:46 PM

Does anyone have any knowledge or experience in road racing a 1972 911, specifically in regards to possible oil starvation of the engine. I have heard rumors that with the oil tank being smaller and in a different location (forward of the rear wheel well), in some dynamic situations oil flow to the engine can be interrupted. Can any one substantiate this?

Thanks,

JB

Tinker · 10-12-2004, 08:07 PM

JB,

I know Jack O had his tank enlarged and it might not be a bad idea since the whole oiling system out of the 72 is 2+ quarts smaller in capacity than other 911's.

However, I have been running a big motor in mine for over 8 years. I am not talking just street driving, but wheel to wheel racing with R compound tires and high loads. I run my oil level near or over the top mark on the oil dip stick when on the track. I have not witnessed or noticed any pressure problems in my car.

Tinker

JB · 10-13-2004, 07:10 AM

Tinker, Do you have an oil catch tank on your car? Any problems with excessive oil blow by? Thanks for sharing your thoughts & experience.

JB

Tinker · 10-13-2004, 10:05 AM

JB,

No catch tank. I routed the tank breather so it terminates at a small K & N filter elevated near the top of the engine bay. Under hard G loads when the tank is slightly overfilled, I get an occassional small/minor spot of oil that ends up on the engine tin on the right side.

No blowby. Blowby would probably be a product of high case pressures due to worn rings.

Tinker

cstreit · cstreit's Garage

Tinker,

THis is the 3rd forum you've posted this question to. Did you look at my response in the tech forum?

1972 911S Oil Starvation Question

911SCfanatic · 911SCfanatic's Garage

Quote:

THis is the 3rd forum you've posted this question to.

One sure way to piss Wayne off.

Eagledriver · 10-14-2004, 10:25 PM

I have a 72 race car with the stock tank. I think the 72 tank is better than the other years because the shape of the tank tapers at the bottom and so there is less area down there for the oil to slosh around in. I do the same think as Tinker and have had no oil pressure problems as long as the oil level is kept right at the full mark. I have noticed that if the I let the oil level drop more than a 1/2 quart then on some left hand corners I can see "pulsing" of the oil pressure guage. This had happened quite abit a couple of years ago before I figured out to keep the level high. I was worried that there could have been damage, but I had the engine apart last winter and the bearings were all still in good shape.

I think if you keep the oil level at the top mark you'll have no problems. I also have the later sump venturi pickup for the oil pump.

I tried the oil line restrictors on my car expecting it to help keep the oil level higher but I noticed the same "pulsing" if the oil level got more than about 1/2 quart low. I took the restrictors back off as I was getting too much oil pressure.

-Andy

JB · 10-15-2004, 07:02 AM

Andy, thanks for your input. I am a firm believer in keeping the oil tank level full even on rear mounted tanks (at least pre '72). About 10 years ago at my first PCA club race, I was having a problem with what appeared to be oil blow by & leaky breather hoses leaving lots of oil on top of the motor & smoke as it dripped on the exhaust. A well known local (to the race) mechanic told me to run the oil level several quarts low, that it wouldn't be a problem. I didn't have a problem at that race but several months later I spun a #2 rod bearing. I couldn't be 100% sure that was the cause but I have had no problems running at the full level since then; except when I accidentally over filled it. Then I had lots of oil blow by, filling my catch tank.

Thanks,

JB

P.S. Chris, I am the one who posted this question in three forms hoping to get varied viewpoints and experience. I did read your posts & about your baffle modification and about the cam tower fittings and am taking that information into consideration. I appreciate your input!