Oil pump for '63 340hp

[Irby G.]

Is it okay to put in a high volume oil pump (Melling M55HV)? Just wondering if it will affect the 'normal' reading on the oil pres gauge. If it does create a little higher than usual pressure, and the car is being judged, will that be grounds for point(s) deduction? Aloha!

[mike mccagh]

Re: Oil pump for '63 340hp

the high press, high vol pump(aka LT-1 pump) will cost you operations points and will almost certainly cause the car to fail it's PV. i usually use the LT-1 pump(like the high vol. feature) but install the weaker spring(which reduces the hot idle pressure to PV-acceptable levels.. mike

[Dwight P.]

Re: Oil pump for '63 340hp

Mike:

Are the weaker springs available from the pump manufacturer or ???? and are the springs rated according to output pressure?

Thanks,

Dwight

[Duke W.]

Re: Oil pump for '63 340hp

There is absolutely no reason to install a "high volume oil pump", but several reasons not to. The 340 HP engine used the same pump as other 327s, except very late versions, which used the same pump, but a 55-60 psi relief spring along with an 80 psi gage in the IP.

The additional volume of a high volume pump is just bypassed past the relief spring, which increases parasitic power loss and heats up the oil.

A high volume pump is only necessary on a loose-clearanced high rev racing engine.

Just buy a standard volume pump with a 40-45 psi relief spring if you have a 60 psi gage.

Duke

[Joe L.]

Re: Oil pump for '63 340hp

Irby----

Forget a high volume pump for a small block. You will gain nothing and lose far more.

If your car has a 60 lb oil gauge, use oil pump GM #12555284. If it has an 80 lb gauge, use pump GM #12555884.

[Joe L.]

Re: Oil pump for '63 340hp

Dwight----

For standard pressure small block pumps use pressure relief spring GM #3814903. For high pressure small block pumps use spring GM #3848911. I believe that these springs will also work ok in Melling oil pumps.

[Mike M.]

Re: Oil pump for '63 340hp

I had the melling M55HV in my 327/350hp. The pressure reading was to high to pass a PV. Pegging the gauge when cold and to high a reading when stepping on it. Joe recomended GM #3814903. It work great with the melling pump. Pressure is now normal. Mid range when running and just past center when cold starting.
Mike

[Joe L.]

Re: Oil pump for '63 340hp

Mike-----

The Melling M55HV is a high volume, high pressure pump. Keep in mind that while installing the GM #3814903 pressure relief spring has converted it to standard pressure, you still have the "high volume" pump characteristics. There's no way to change that without changing the complete pump. The original pump for your application was a standard volume pump, as were ALL small block Chevrolet PRODUCTION oil pumps. The high volume pump won't cause you any problems as far as PV issues are concerned since there's absolutely no way of discerning the high volume characteristics of the pump installed on the car. However, it's possible, while unlikely, that the high volume pump could cause other problems. High volume pumps are, primarily, designed to be used with applications having increased oil pan capacity. As I say, it's unlikely that you'll have any problems with the high volume pump, but it's not totally beyond the realm of possibility.

[Mike M.]

Wrong Part Number For Melling Pump

Joe, I put the wrong number for my melling pump. It's a 55A which is a high pressure pump. Not the high volume. Mike

[Joe L.]

Re: Wrong Part Number For Melling Pump

Mike-----

That's different. In that case, by replacing the pressure relief spring you've converted the M-55A to an M-55 which should be the correct pump for your engine if you have a 60 lb oil gauge.

[Irby G.]

Thanks to all. This is exactly what I was looking

Aloha, Irby