Fail PV if high-pressure oil pump??

[Joe L.]

Re: Fail PV if high-pressure oil pump??

Thanks for the info Joe. I was responding to the OP about his '66 L79. But I always learn a lot from all the posts I read. Now I know a little more about C1 motors. I know that some of the C2 fuelies and solid lifter small blocks had 80lb gauges. Did they have higher pressure pumps as well, or just higher reading gauges? And did the later C1 fuelies and solid lifter motors, like the 62's, have the standard pressure pumps?

Mike

Mike------

The 1962 340 and 360 HP, as well as all earlier mechanical lifter small blocks were equipped with standard pressure oil pumps. As a matter of fact, so were early 1963 340 and 360 HP. The only PRODUCTION small blocks that EVER used the high pressure pump were L1963-65 with mechanical lifters and 1970-72 LT-1. The L63-65 with mechanical lifters were also equipped with 80 lb oil gauges. All 68-72 were equipped with 70 lb oil gauges.

[Michael M.]

Re: Fail PV if high-pressure oil pump??

[QUOTE=Joe Lucia (12484);701103]Mike------

The 1962 340 and 360 HP, as well as all earlier mechanical lifter small blocks were equipped with standard pressure oil pumps. As a matter of fact, so were early 1963 340 and 360 HP. The only PRODUCTION small blocks that EVER used the high pressure pump were L1963-65 with mechanical lifters and 1970-72 LT-1. The L63-65 with mechanical lifters were also equipped with 80 lb oil gauges. All 68-72 were equipped with 70 lb oil gauges.[

I guess enough people managed to blow them up with the standard oil pump that GM switched to the higher volume pump and used the bigger oil pan to keep them from pumping it dry.

[Joe L.]

Re: Fail PV if high-pressure oil pump??

[QUOTE=Michael Murphy (52144);701107]

Mike------

The 1962 340 and 360 HP, as well as all earlier mechanical lifter small blocks were equipped with standard pressure oil pumps. As a matter of fact, so were early 1963 340 and 360 HP. The only PRODUCTION small blocks that EVER used the high pressure pump were L1963-65 with mechanical lifters and 1970-72 LT-1. The L63-65 with mechanical lifters were also equipped with 80 lb oil gauges. All 68-72 were equipped with 70 lb oil gauges.[

I guess enough people managed to blow them up with the standard oil pump that GM switched to the higher volume pump and used the bigger oil pan to keep them from pumping it dry.

Michael-----


It was not a high VOLUME pump. It was a high PRESSURE pump. As I mentioned previously, no PRODUCTION Chevrolet small block EVER used a high volume pump.

[Michael M.]

Re: Fail PV if high-pressure oil pump??

[QUOTE=Joe Lucia (12484);701185]

Michael-----


It was not a high VOLUME pump. It was a high PRESSURE pump. As I mentioned previously, no PRODUCTION Chevrolet small block EVER used a high volume pump.

Ah, yes. Of course you're right, it was a discussion about high/low pressure pumps & gauges after all. I can see the need for higher pressure with an engine that revs higher. So why the larger oil pan or was it just shaped different? Did the larger oil volume( in the pan) help dissipate heat? Or was it to keep the pump submerged when cornering? Both? Wouldn't a higher volume pump have helped as well? Especially with heat dissipation? Since you have a bigger oil pan anyway. I'm not qualified to second guess the chevy engineers, just wondering what they were thinking.

Thanks Joe.

[Joe L.]

Re: Fail PV if high-pressure oil pump??

[QUOTE=Michael Murphy (52144);701192]

Ah, yes. Of course you're right, it was a discussion about high/low pressure pumps & gauges after all. I can see the need for higher pressure with an engine that revs higher. So why the larger oil pan or was it just shaped different? Did the larger oil volume( in the pan) help dissipate heat? Or was it to keep the pump submerged when cornering? Both? Wouldn't a higher volume pump have helped as well? Especially with heat dissipation? Since you have a bigger oil pan anyway. I'm not qualified to second guess the chevy engineers, just wondering what they were thinking.

Thanks Joe.

Michael-----

The 63-65 SHP pan was 1 quart larger than the standard pan. For 1970-72 LT-1, though, only early 1970 and all ZR-1 used the higher capacity pan. The rest used the high pressure pump but standard pan (exact same as 63-67 standard pan).

[Dick W.]

Re: Fail PV if high-pressure oil pump??

[QUOTE=Michael Murphy (52144);701192]

Ah, yes. Of course you're right, it was a discussion about high/low pressure pumps & gauges after all. I can see the need for higher pressure with an engine that revs higher. So why the larger oil pan or was it just shaped different? Did the larger oil volume( in the pan) help dissipate heat? Or was it to keep the pump submerged when cornering? Both? Wouldn't a higher volume pump have helped as well? Especially with heat dissipation? Since you have a bigger oil pan anyway. I'm not qualified to second guess the chevy engineers, just wondering what they were thinking.

Thanks Joe.

The higher the pressure, the more heat generated. Racing engines today use very thin oil and very minimum pressure. Just opposite of what we did 40 years ago. Takes hp to generate pressure.

[Michael M.]

[Timothy B.]

Re: Fail PV if high-pressure oil pump??

Micheal,

Thanks for posting the end results, this information will help many people.

On my 300hp engine I have the M-55 and did not realize the spring needed to be changed so the hot oil pressure will just peg the 60psi gauge. Some day I will probably fix it but I am just pissed off having to remove the pan again.

I think the Melling pump is a very nice product though.

Michael, does the pump pressure max out at 45psi at rpm's above 2000-3000 etc. like a stock GM pump.

[Michael M.]

Re: Fail PV if high-pressure oil pump??

Michael, does the pump pressure max out at 45psi at rpm's above 2000-3000 etc. like a stock GM pump.

Timothy, no, my pressure increased somewhat with RPM above 2000. It was dead nuts on the 45psi line at 2000 RPM, about 50psi at 3000 and maybe a bit higher over that.

[Dennis O.]

Re: Fail PV if high-pressure oil pump??

I hate to be the bearer of bad tidings, but that is still too high. Hopefully, not enough to cause PV problems, but not to Chevrolet specs. You want the Melling 49 lb (green) spring for the Melling pump. This is why I went against the advice of several of the experienced members here who recommended getting a GM spring to install in my new Mellings standard pump. The green spring from Melling works properly with their pump. It is best not to mix parts in a situation like this.

[Timothy B.]

Re: Fail PV if high-pressure oil pump??

Michael,

Thanks for posting the information about your engine oil pump spring relief pressure.

I think the engine will be fine just the way you have it now.

[Dennis O.]

Re: Fail PV if high-pressure oil pump??

I too, am sure his engine will be just fine the way it is. However, the original post asked about high oil pressure and passing PV. On that, I'm not so sure.

While I'm posting, Id like to let everyone know that the standard volume Melling pump does not come the correct spring. The one I got from Summit last summer came with the high pressure spring installed, and the medium pressure (yellow 58#) in a plastic bag in the box. I corresponded with the engineering department at Melling about this, and they sent the proper (green 49#) spring gratis. So although someone on here correctly suggested changing the installed spring for the yellow one in the bag, a little more effort may have to be expended if a PV is going to be considered.

[Timothy B.]

Re: Fail PV if high-pressure oil pump??

Dennis,

I agree with you also about the Melling springs, I did exactly as you calling Melling and getting the green spring. It was to late for me to change but from my memory I thought the spring still seemed stiff that's why I thought the GM spring may work better.

Another option if you want to use a new oil pump and have a old GM pump cover to install. I believe this will work fine also but have never tried it. After reading Michael's results I think at this point I would try Duke's suggestion and use a Federal Mogul pump but I find it hard to believe it's not a Melling pump. Maybe someone here can post a picture of that replacement pump.

[Bruce W.]

Re: Fail PV if high-pressure oil pump??

Thanks Mike, I ordered the GM spring. I don't even know what pump is in the engine I do know that 45 lbs at idle is too high. Engine was rebuilt it seems as if some rebuilders automatically put in the high volume pump I understand there is only one bolt to hold in the pump? Is that true. Do you know if there is a torque specification on the pump bolt? Also did you try running 10w 30 to see if that brought down the pressure? I am interested in trying to pass the PVBruce

[Joe L.]

Re: Fail PV if high-pressure oil pump??

Thanks Mike, I ordered the GM spring. I don't even know what pump is in the engine I do know that 45 lbs at idle is too high. Engine was rebuilt it seems as if some rebuilders automatically put in the high volume pump I understand there is only one bolt to hold in the pump? Is that true. Do you know if there is a torque specification on the pump bolt? Also did you try running 10w 30 to see if that brought down the pressure? I am interested in trying to pass the PVBruce

Bruce------


One bolt retains the pump to the rear main cap. There are no washers of any kind on this bolt. The torque is 65 lb/feet.

If the pump turns out to be a high volume pump, I highly recommend you replace it with a standard volume pump. How can you tell the difference? Well, some folks can tell just by looking at the pump body. But, if you can't, simply remove the pump cover (4 small bolts) and measure the length of the gears. Standard volume= 1.3"; high volume = 1.5".

If there are any casting marks anywhere on the body that say "HV", then you know it's a high volume pump just from that.