Big Block oil pressure

[Hank H.]

Can someone help me with the acceptable llimits for oil pressure on a 69, 435 car in order to pass a PV?Mine tends to run about 55lbs or a little higher at slow cruise speed, although PV manual states that even big block 435s should be in the 40-45 lb range. How closely is this judged for a PV test and should I change to a lower HP (390) oil pump? The car presently has a "correct" pump for 435 and L88 cars. thanks

[Dick W.]

Re: Big Block oil pressure

Hank, PV judges pretty much go by the book, so if the book says ..... that is the standard that you will be tested to. Having done '68-'69 PV's for 10 years as a team leader, you would fail. It sounds like that you have a high volume pump. You might get by changing the pressure relief valve spring.

Book is pretty close. One failed PV a couple of months ago for incorrect cam shaft. It was a 435 and probably had a L/88 cam in it. No vacuum at idle to operate headlamps and wiper door. Engine did not completely smooth out until about 1,200-1,300 rpm's.

Always remember, you cannot do a practice PV too many times. Have your friends act as the tester.

[Pat M.]

Re: Big Block oil pressure

Hank - While I'm sure Dick's right, you may want to ask your 68-69 Team Leader directly, who I think is Chuck Berge. Chuck's a super nice guy, and I'm sure would be happy to tell you what he expects.
The 70-72 Team Leader, Stan Falenski, was very kind and responsive to several questions I posed prior to the PV on my 70, and I would think Chuck would do the same.
In a sense, both Flight Judging and PV are an "open book test", in that, you can ask each judge what they expect, and prepare accordingly. After all, why not go straight to the source?
Good Luck

[Duke W.]

Re: Big Block oil pressure

What do the '69 AMA specs say about oil pressure for a L-71?

I have a copy of the '67 AMA specs and it says:

327 CID, 30-45 psi @ 1500 RPM
427 CID, 50-75 psi @ 2000 RPM

These values are for a fully warmed up engine, including oil, which will take longer to warm up to normal temperature than the coolant - say at least 10-15 minutes of around town driving in mild weather. Cold pressure may be higher and hot idle pressure is lower.

Also, as a general rule, if the oil pressure gage is calibrated to 80 psi the engine will run 55-60 hot at 2000-up, if calibrated to 60 psi the normal hot oil pressure at 2000-up is 40-45 psi.

The best time to check oil pressure is toward the end of the PV when the oil temperataure should be fully normalized.

Duke

[Joe L.]

Re: Big Block oil pressure

Can someone help me with the acceptable llimits for oil pressure on a 69, 435 car in order to pass a PV?Mine tends to run about 55lbs or a little higher at slow cruise speed, although PV manual states that even big block 435s should be in the 40-45 lb range. How closely is this judged for a PV test and should I change to a lower HP (390) oil pump? The car presently has a "correct" pump for 435 and L88 cars. thanks

Hank-----


The L-71 and L-88 oil pumps were NOT the same. However, the pressure relief spring (and, consequently, the oil pressure generated) were the same. The spring should have 24 coils, 5/16" OD, and a free length of 2-7/16".

So, what was the difference between the pumps for L-71 and L-88? The pumps were basically the same but the pick-up screen was different for L-88 and L-71. The L-88 screen was never available as a separate piece from GM and was supplied with the pump. Both pumps were standard volume, high pressure.

The configuration of the L-71 and L-88 screens was COMPLETELY different and not just a subtle difference.