Oil Pump - too much pressure?
#1
Melting Slicks
Thread Starter
Oil Pump - too much pressure?
I took my car to the shop to replace the oil pan. Its a 427/435 and the pan was pretty beat up. Anyway - while inside the motor, the shop identified that the pump was partially plugged. (See pic - gives credibility to being careful when applying sealant). Although the pressure would go way up when in race mode (60++), the idle pressure was low (5-15).
I previously had pump # 390 6629 88 GM 22 (can anyone identify?) :confused: and was happy with it. It gave fair pressure at normal operating and volume/pressure went up appropriately with high RPM's.
For years, I have always been a supporter of high volume over high pressure. The shop said they would put in an equal pump and installed M77HV (can anyone identify this one?) :confused: At idle it has 70 psi ! :eek: I am sure the volume is there, but isn't this overkill at idle? Granted, the hot Houston summers will thin the oil and pressure will drop. Any thoughts?
Thanks, kaiserbud
[Modified by kaiserbud, 11:23 AM 3/30/2002]
I previously had pump # 390 6629 88 GM 22 (can anyone identify?) :confused: and was happy with it. It gave fair pressure at normal operating and volume/pressure went up appropriately with high RPM's.
For years, I have always been a supporter of high volume over high pressure. The shop said they would put in an equal pump and installed M77HV (can anyone identify this one?) :confused: At idle it has 70 psi ! :eek: I am sure the volume is there, but isn't this overkill at idle? Granted, the hot Houston summers will thin the oil and pressure will drop. Any thoughts?
Thanks, kaiserbud
[Modified by kaiserbud, 11:23 AM 3/30/2002]
#2
Re: Oil Pump - too much pressure? (kaiserbud)
The 77HV is a Melling High Volume pump for big block that'll come with 2 springs and a 3/4 inch pick-up tube inlet. A colored High pressure spring and a "regular" pressure spring. I'm not sure what the PSI difference is between the two spring are. I like Melling pumps I've used several never a problem. I have the 55HV (smallblock) with high pressure spring in, with Mobil Synthetic 5W-30 I have 80 PSI cold and 40 PSI hot at idle and 60 PSI hot at cruise. Hope that helps.
Scott
[Modified by Scott78, 11:23 AM 3/30/2002]
Scott
[Modified by Scott78, 11:23 AM 3/30/2002]
#3
Race Director
Re: Oil Pump - too much pressure? (kaiserbud)
I don't like HV pumps on big blocks. As you can see, idle pressure is way up there. I had the same pump and buried the needle over 1500 rpm, even when hot. I feel the high pressure promotes leaks and increases stress on the distributor gear.
I switched to the regular melling pump (same PN, but no HV at the end). I used the corvette spring that it came with. I now have 35 PSI hot idle and 60 at high rpm.
I switched to the regular melling pump (same PN, but no HV at the end). I used the corvette spring that it came with. I now have 35 PSI hot idle and 60 at high rpm.
#4
Melting Slicks
Thread Starter
Re: Oil Pump - too much pressure? (zwede)
Markus - Scott
Appreciate the info. I still would like to figure the old part number info. I have to agree with Markus regarding high pressure - I think the HV (High Volume) is very appropriate for a big block - moreso in the heat of Houston. I may pull it out again and look. I wasn't happy with the work this shop did in many aspects. Future posts will discuss other issues.
Can anybody adivise the old ol piump specs?
Thanks Markus and Scott
Appreciate the info. I still would like to figure the old part number info. I have to agree with Markus regarding high pressure - I think the HV (High Volume) is very appropriate for a big block - moreso in the heat of Houston. I may pull it out again and look. I wasn't happy with the work this shop did in many aspects. Future posts will discuss other issues.
Can anybody adivise the old ol piump specs?
Thanks Markus and Scott