Improve oil drain back with Glyptol?

[Michael H.]

Re: Improve oil drain back with Glyptol?

yes BBC have lots of intermal oil losses so using a volume pump is OK BUt i would add 1 quard over full if you plan on running the engine to the redline. my 66 427 corvette would start to loose oil pressure going thru the gears unless i ran 1 quart over full and it does hurt anything because 1 quart over the oil is still below the windage tray.

Yup, lot of oil up in an area where it doesn't belong with a high volume/pressure pump. A street big block doesn't need the kind of oil pressure that a ZL1 oil pump produces.

That ZL1 pump is designed for high RPM with oil at operating temp. It's straining it's guts out before the oil is hot, which is what most old restored Corvettes see now.

I installed a correct oil pump in my 425 HP 66 engine at overhaul 26 years ago and it has no issues. It doesn't eat distributor bushings either like it would if it had the high pressure pump.

[Clem Z.]

Re: Improve oil drain back with Glyptol?

Yup, lot of oil up in an area where it doesn't belong with a high volume/pressure pump. A street big block doesn't need the kind of oil pressure that a ZL1 oil pump produces.

That ZL1 pump is designed for high RPM with oil at operating temp. It's straining it's guts out before the oil is hot, which is what most old restored Corvettes see now.

I installed a correct oil pump in my 425 HP 66 engine at overhaul 26 years ago and it has no issues. It doesn't eat distributor bushings either like it would if it had the high pressure pump.

my 66 had the factory pump and i would assume the oil was not returning to the pan fast enough. the stock BBC used piddle valve lifters which put a lot of oil up into the rocker covers that must not have bee returning to the pan fast enough.

[Joe L.]

Re: Improve oil drain back with Glyptol?

Yup, lot of oil up in an area where it doesn't belong with a high volume/pressure pump. A street big block doesn't need the kind of oil pressure that a ZL1 oil pump produces.

That ZL1 pump is designed for high RPM with oil at operating temp. It's straining it's guts out before the oil is hot, which is what most old restored Corvettes see now.

I installed a correct oil pump in my 425 HP 66 engine at overhaul 26 years ago and it has no issues. It doesn't eat distributor bushings either like it would if it had the high pressure pump.

Michael------

A 1966-69 SHP big block original oil pump uses the exact same pressure relief spring and produces essentially the same oil pressure as the ZL-1 oil pump. The ZL-1 pump only adds "high volume".

[Michael H.]

Re: Improve oil drain back with Glyptol?

my 66 had the factory pump and i would assume the oil was not returning to the pan fast enough. the stock BBC used piddle valve lifters which put a lot of oil up into the rocker covers that must not have bee returning to the pan fast enough.

Yes, I agree. And a ZL1 pump would make the problem even worse.

I suppose a little more oil on the valve springs, to cool them, wouldn't be a bad idea IF someone were using the original 65-69 single wire springs but I doubt anyone is doing that. That single wire design ran VERY hot and failed often.

I think the part number on 65-66 mech lifters changed some time around mid 1966 but I don't remember what the change was. It may have had to do with overhead oil flow?

[Michael H.]

Re: Improve oil drain back with Glyptol?

Michael------

A 1966-69 SHP big block original oil pump uses the exact same pressure relief spring and produces essentially the same oil pressure as the ZL-1 oil pump. The ZL-1 pump only adds "high volume".

Oh. If that's the case, then I agree with you. I thought the L88/ZL1 spring was a different part.

[Clem Z.]

Re: Improve oil drain back with Glyptol?

Yes, I agree. And a ZL1 pump would make the problem even worse.

I suppose a little more oil on the valve springs, to cool them, wouldn't be a bad idea IF someone were using the original 65-69 single wire springs but I doubt anyone is doing that. That single wire design ran VERY hot and failed often.

I think the part number on 65-66 mech lifters changed some time around mid 1966 but I don't remember what the change was. It may have had to do with overhead oil flow?

i think GM was trying to make sure the rocker arm balls would not burn from lack of oil as the valve spring pressure was greater than with a SBC. we always use edge orifice lifters when we used needle bearing rockers because they did not need all that oil flow. i used edge orifice lifters in drag race engines with stock rocker arms but i always installed well broken in rocker arm/ball set up because with the stock oil pan it would run out of oil before the end of the 1/4 mile

[Joe L.]

Re: Improve oil drain back with Glyptol?

Oh. If that's the case, then I agree with you. I thought the L88/ZL1 spring was a different part.

Michael-----


GM #3876866 pressure relief spring was used for all SHP and HD Mark IV pumps. As a separate part, it's long-since GM-discontinued. However, if you buy a ZL-1 pump, you get one with the pump. The SHP pumps are long-since GM discontinued.

Melling and others can supply the SHP pumps, though, and I expect they can supply an equivalent of the 3876866 spring, too.

[Michael H.]

Re: Improve oil drain back with Glyptol?

Michael-----


GM #3876866 pressure relief spring was used for all SHP and HD Mark IV pumps. .

Yes, you are correct. I don't know why I was thinking L88 and ZL1 had a unique pressure relief spring. They just had a unique oil pump.

[Dick W.]

Re: Improve oil drain back with Glyptol?

Yes, you are correct. I don't know why I was thinking L88 and ZL1 had a unique pressure relief spring. They just had a unique oil pump.

It gets worse with age Cranky!

[Michael H.]

Re: Improve oil drain back with Glyptol?

It gets worse with age Cranky!

It already GOT worse with age, Dick. If I go to the other part of the house after more than two items, I need a note.

[Dick W.]

Re: Improve oil drain back with Glyptol?

It already GOT worse with age, Dick. If I go to the other part of the house after more than two items, I need a note.

I usually do not make it to the other side of the house. I find something that I have lost, need to do, etc.