My smallblock is leaking a little oil from the bottom end (front and rear seals) so I am going to do a reseal. I figured while I had the pan down, I would change the oil pump (due to the fact it has 180,000 original miles on it).
My question is, the replacement oil pump I bought has both the high pressure spring (installed) and the standard pressure spring (in a little bag). Should I use the higher pressure spring, knowing my oil clearances are looser now due to wear or should I use the standard spring and just live with the slightly reduced oil pressure caused by the worn bearings.
Can you think of any reason why the higher pressure spring might be a bad idea?
Thanks

 

I wouldn't risk changing it on a high mileage engine you might discover other leaks you did not have before. On one of my vehicles I went from a standard oil pump to a high volume pump and did not replace the oil pan with a high performance baffled pan. Upon heavy brakeing I can drop the oil pressure to 0 psi. If it were me I would roll a set of bearings in the car while the pan if off. :cheers:

 

Thanks Chris. I have gotten a couple of replies to my question and you all say the basically the same thing "stick with the standard spring", so I will head your advice and go withthe standard pressure.
BTW, I noticed you live in LV too.......it seems theres more Corvettes here than Bowlng Green, KY!!

 

Ghost, chre is talking about using a high volume pump in his car. That is where his problem came from. I run a Melling M-55A pump in my '87 which is a standard volume high pressure pump without problems.

With the pan off it isn't too hard to change the rod bearings if you wanted to. What are your pressures like now?

p.s.

I have no idea what pump part # to use in an LT1.


[Modified by scorp508, 3:12 PM 11/4/2003]

 

Now you got me confused Scorp :confused:

If it is high pressure, doesn't it mean it must be high volume? The oilways are the same size, so if you increase the pressure the flow rate (volume) must increase. Or am I :confused:


I've a feeling I might be missing something here (a brain?) :)

 

I don't know the exact mechanics of it, but if I had to guess the same volume of oil is just pushed out through a smaller opening creating the higher pressure at the pump.

 

Now I am even more confused! Who gives a F what the pressure is at the pump, it's the pressure at the bearing surfaces that concerns me. :confused:

 

The pump is the driving force behind all of those pressures at the bearings. It has to get there somehow. If a pump can force oil into all of the oil passages at a higher pressure then everything benefits.

 

Corvettes in Kentucky have 4x4 monster tires, gun racks, and are usually painted camflouge :lol:

I know....my family is from KY.

 

Hmm. So if it is higher pressure , then it must be higher volume- right?. I am not so sure it is good for the distributor (HEI) though.

I have one of those high pressure jetwash thingies, and I don't really know how it works. Never really though about it, but there is some sort of electric motor in there that boosts the mains water pressure, but I suspect that it may be at the expense of volume, but there again why not just hold your finger part way over the hose nozzle ???

See what I mean - I have a horrible feeling there is more to this than meets the eye.

Anyway, I am going out to the garage now to continue with my cam swap.

Oh - and I recommend a standard pressure, standard volume oil pump by the way. High pressure will mess with your distributor and timimg.

Cheers

J

 

OK! Here's the deal on high pressure and high volume oil pumps. The oil pump has a pressure regulator built into it. Sometimes it's called a "bypass", sometimes it's called, a "relief valve". When the pressure exceeds the relief pressure the excess oil and pressure are dumped. A high pressure pump has a stronger pressure relief spring and puts out more pressure. The high volume pump, has longer gears. Each rotation of the pump displaces (moves) more oil. A high volume pump can have the relief spring pressure increased, too. Ultimately, past the pump, the engine clearences become the "pressure regulator". Large clearences bleed off volume and pressure. Check your oil pressure after you've spun a bearing. A high volume pump can cause higher pressures in a "tight" engine. There is less "relief" built into the bearing clearences. Also, higher pressures, cause the input shaft to require more power to turn. This consumes power that might otherwise make it to the rear wheels. It also places a higher load on the cam & disributor gears, not to mention the timing chain and sprockets. There is no free lunch. Everything has it's trade-offs. Oil pumps 101, class dismissed. There WILL be a quiz, tomorrow. Good luck, all,and...

RACE ON!!!

 

CFI- EFI - this is why I come to the forum. Now I have learnt something. So, within reason, the volume and pressure can be determined at will. So, for a standard engine (?) with standard wear and clearances(?), I would guess that GM's compromise is probably about right. Thanks for that . (really)

Must go now - have to revise for the exam in the morning!!!

 

I don't see to many C4s but I see a ton of C5s. Just remember to :seeya if you see me. :cheers: