Installing HV Melling oil pump

[Tom87GNX]

I'm going to be installing a HV Melling oil pump, any recommendations as to what spring I should use? Kit has springs for 40, 60, and 70 psi. I'm thinking 70 but I'm no expert on these engines. Thanks for any input on this.

Tom

 

[Buick Mark]

You dont need the high volume pump, the stock pump with the booster plate will do fine. Make sure to set the gear end clearance to .002

 

[earlbrown]

Take that pump back and get a normal one. A properly set up stock pump will flow more than enough to keep our engines happy.

 

[ek02]

X 3. Get an adjustable pressure regulator kit from TA and you can get any pressure you want above idle from the stock pump with or without a booster plate. I set mine at 60 PSI cold while priming the system with a drill, then see what it is hot and adjust for 70 PSI @ high RPM.

 

[Steve V]

The oil pressure is set by...the bearing clearences in the engine, the clearences in the pump pocket, and the pump gear end play. All those springs do is control what psi the bypass valve opens and you send unfiltered oil into the rest of the engine. That is all the adjustable PR kit does from TA ....correct me if I am wrong gurus.

 

[Tom87GNX]

I thank everyone for their input on this, I've also gotten some tips from Bison, as well as a local GN guru in my area. It seems that there are several different opinions here. The local guru in my area has run the same pump I have for years and has had no problems, he always uses this pump kit in all his turbo builds. He currently has several 11 second turbo cars. So I really don't know which way to go, it seems as though everyone has had different experiences. I'm not trying to split hairs here or anything so, I guess I will do a bit more research before I make a decision. Thanks again everyone.

 

[earlbrown]

The oil pressure is set by...the bearing clearences in the engine, the clearences in the pump pocket, and the pump gear end play. All those springs do is control what psi the bypass valve opens and you send unfiltered oil into the rest of the engine. That is all the adjustable PR kit does from TA ....correct me if I am wrong gurus.

You are. The oil pressure is set by the relief spring on the filter housing. The amount the relief has to open to maintain pressure is dependent on bearing clearances.

When the pump moves more oil than the bearings can hemorrhage, the relief spring allows the valve to unseat. The oil that's bled get's routed back to the pump.

If you look at a timing cover you'll notice the long slot that feeds one side of the gears from the pan pickup.... the bypassed oil feeds the other side of the gears. That's why my "booster hole" I invented works so well. It allows all of the gear face to get oil without the relief having to be opened (and eliminates having to make to 90* turns and a 180 to get there).

By installing a HV pump all you do is move that much more oil though the relief circuit and back into the pump. Any additional load from the taller gears is wasted efficiency pumping oil that doesn't even make it into the engine (and extra load on the front cam bearing, bevel gears, cam sensor pin and timing chain).

 

[TurboBuRick]

I agree with Steve. It only set bypass pressure. Mostly in place for cold start. Very rarely it will bypass on a engine that is up to operating temp.

 

[Tom87GNX]

I believe your correct in theory, bearing clearances do effect oil pressure but as EARL stated. "The oil pressure is set by the relief spring on the filter housing. The amount the relief has to open to maintain pressure is dependent on bearing clearances." With this being said the spring does change pressure, however bearings clearances must also be correct. Bearing clearance vs oil pressure applies to all engines wether it's a turbo buick or a small block Chevy. Obviously it's not a great comparison since they aren't even remotely the same, it's just the principal. Good bearing clearance will provide good pressure assuming the pump is capable of providing good pressure. The fact is I personally have never seen good results with engines that have 10-15 psi at idle. This in my experience with sm chevys this always leads to premature bearing failure. Maybe not the case in turbo Buicks? That I don't know. IMHO I'd rather have 20-25 at idle.

 

[earlbrown]

Bearing clearances only affect oil pressure if they are so loose they leak so much the valve never unseats. On engines with that issue, its not an oil pump problem.

What kind of bad experiences have you had with engines that have double the amount of oil pressure they need at idle?

 

[Tom87GNX]

Earl,

As I stated I'm no expert with Buicks, and I'm aware excessive clearance is what causes pressure issues. Also as stated I've had small Chevys destroy bearings cause of low pressure. Also as stated they are completely different then Buicks. Most Chevys are rated at minimum of 12 at 1,000 RPM but every builder I know will tell you that's not nearly enough for a high perf. engine. Ive never had problems due to having higher then specified oil pressure. As far as my buick, I don't feel comfortable running 10 psi at idle, I'd rather have 20-25 and there is a few members here that agree with me on that. I'm not staying your wrong, just giving my opinion.

 

[Steve V]

If you are going to build your Buick like a Chevy you are in trouble. Buicks have an external aliminum pump while Chevy's have internal cast iron pump. The differences start there. Listen to the people with fast buicks and lots of experience with the 3.8, the idiot light on the dash is set to turn on at 4psi. 15 psi at idle is just fine. I have had engines with 25+ at idle, this is a std crank with std bearings and 5w 30 oil. Pump is std volumne and blueprinted. And I have had them with 15psi at idle. Never had a problem either way.

When I had problems is when I had some junk Chinese front covers and that had casting flash restricting flow and I did not have enough experience with buicks to catch it. Then I got on the forums read and learned and have built 20+ 3.8's for myself and others. I am no pro either.

 

[Tom87GNX]

As I stated in post I KNOW CHEVYS AND BUICKS are different completely. I never stated I was building my buick like a Chevy. I originally just asked for an opinion on what spring to use in my HV pump kit and I was told not to use it. I've also been told by several other members that they used HV pumps with good results. I also stated personally I don't feel comfortable with 10 psi at idle, this is my preference, I'd rather have 20-25 at idle and that's what I'm looking to do. I thank you for your input but I think some people are misunderstanding what I'm saying.

 

[Buick Mark]

Alot of big time racers have zero pressure at idle.

 

[Tom87GNX]

That may be so

 

[Steve V]

GOOD LUCK with your build

 

[Tom87GNX]

Thanks

 

[earlbrown]

Sounds like you won't be able to enjoy your car without ridiculously high pressures. And I can see that. If you don't feel good about the car, it won't be fun to drive.

That being said, I would install the softest spring in the kit (the low pressure one) and shim the shit out of it. Fill the crankcase with 20/50 and run a huge oil cooler after the factory cooler along with a quality biggie filter. With any luck the softer spring rate will relax at upper RPMs and not blow the filter seal, the sammich adapter O-ring, or spin the filter off at speed. (NOTE: I have NO first hand experience in that kind of setup. I've did hundreds of oil systems using stock volume gears and the soft spring with 100% success rate so I'm kinda stuck in my ways)

If you have the original timing set, change it before you run the above setup as it will take all the teeth off the top gear and deposit them into the pan.

 

[Tom87GNX]

Thanks Earl,

I actually just talked to a good friend of mine, he runs this pump with a 60psi spring and 10w 30. He says it works perfect, his engine has over 50K on rebuild and still running strong with no issues. He's actually the guy doing my bottom end. He's been building GN motors since the early 90's.

BTW, I do have a new timing set with a steel cam gear. Thanks for the heads up though.

 

[ek02]

We are all measuring oil pressure at the front of the block. Has anyone plumbed an oil pressure guage in at the rear of the block on the oil passage plug? I wonder what the pressure is as it gets to the rear main on an engine with the correct clearances?