Oil pump problem

[GoMangoBoys]

We tried to install or oil pump today and ran into a problem.  While torquing the bolts to the spec in our book (35 ft#), the corner of the pump cracked.  So, I have 2 questions.
1.  Is 35 ft# too high for the oil pump bolts?
2.  When I buy another pump, should I get a high pressure or high volume pump?
FYI, Our engine is a 383 stroked to 478.  Cast iron heads.

[chargerdon]

In my 66 Charger with a mildly built 383 4V after doing a mild overhaul i had low oil pressure when at full temperature and at 700 RPM idle in drive my oil pressure would drop to about 5 PSI on a mechanical gauge.   I put in the High Volume Pump and now i have 65-70 PSI cold and when hot and idling about 10-12 psi.   So i called Melling and asked about High Pressure vs High Volume vs standard Oil Pump...   The Melling rep told me that a High Volume pump is NOT a fix for a worn engine with worn bearings but can help in situations like mine.  The Melling Rep explained that a standard oil pump has a spring in it that maximizes the amount of pressure that a pump can make which for a Mopar is about 70-75 PSI.   A High Pressure Pump has a stronger spring and will allow the pump to reach about 100 PSI max.   At low RPM there is zero difference !!  You can increase the MAX pressure from a std pump by simply removing the spring and replacing it, or even just adding in a couple of washers does the same thing.

Conversely, a High Volume Pump will increase the amount of oil being pumped across the board by about 25%.   It will also take more power to run the Pump as it is pumping more oil.  However it is still being held to about 75 PSI max by the overload spring.

So, if you have any concerns about having enough oil pressure, like in an engine with racing bearings which typically have lower tolerances then a high volume pump is a good idea.   Many say do not put in a High Volume Pump if you plan on doing any drag racing or track racing as the High Volume Pump at high RPMs could pump all of the oil out of the sump !!!!!      Melling rep told me that isnt true unless the return passages are clogged, as the HIGH Volume Pump has a STANDARD spring to limit max pressure to the same as a standard pump and therefore that wont happen.   

  Several engine builders put High Volume Pumps in all of the engine builds.. 

MY two cents...put in the high volume pump...   

[RUNCHARGER]

I ran a high volume pump on the 383 in my FM3 Challenger and on a highway run I would watch the oil pressure gauge twitch. So I added an extra quart of oil (overfilling) and that took care of it. I would not recommend a HV pump with a stock 383 pan after that experience. It should be okay with the larger Hemi/Six Pack oil pan. I can't remember the clearances on that 383 off the top of my head but I remember I ran full groove main bearings in it, would have been either .0015 or .002 clearance.

[Strawdawg]

With regard to the cracked ear, it sounds to me as if the pump was cocked and the ear did not sit flush.  Otherwise, there should not have been any "bending" force on the ear.

As far as the pump goes, an engine with normal clearances should not need a HV pump but the high pressure spring may be desirable if the engine is going to be turned higher than stock.  If the engine has not been built for racing purposes with larger clearances, I think it might be time to look at the bearings to check if an over haul is in your future...

If there is a reason that you need more volume, be sure you have a larger pan and a beefed up pump drive

[Chryco Psycho]

35 Ft Lbs is fine if everything is flat & lined up .
I agree with Dons explanation on pumps But I disagree , on a stock engine HP pump ONLY .