Question: Oil pump specs

[Kid_Again]

I have a continuing problem with too high oil pressure in the SB. I've swapped out the oil pump once for a Summit standard pressure pump and I still have high oil pressure. For example, I peg the oil gauge at start up, it shows 60#+ at speed and i have oil leaks which seem to come from the valve covers.

I just pulled the original pump and it has 1.25" tall gears. Is that a SHP pump or standard? I suppose I could also make sure I have a standard pressure spring. Any idea where to get the springs?

Although I'll do a complete diagnostic on the problem (with the help of VNV), I'm on the verge of saying that there's an obstruction in the block somewhere and just swap out a 383 short block.

Any thoughts?

Thanks

 

[JohnZ]

Small-block pumps have four-bolt covers, and differ only due to the installed relief spring. The "high-volume" pump (which was never used in production) is actually a big-block pump with longer gears with more teeth and a five-bolt cover.

I wouldn't worry about that oil pressure - my '67 327/300, rebuilt about six years ago, pegs the gauge at cold start, and when fully warmed up, has 35psi at idle and 50-55 psi cruising down the road. I have zero leaks, even with stamped valve covers. If it really bugs you, change the spring. I have the numbers somewhere for both springs, but I can't locate them right now - your Chevy parts counter guy should have them.

 

[Kid_Again]

Small-block pumps have four-bolt covers, and differ only due to the installed relief spring. The "high-volume" pump (which was never used in production) is actually a big-block pump with longer gears with more teeth and a five-bolt cover.

I wouldn't worry about that oil pressure - my '67 327/300, rebuilt about six years ago, pegs the gauge at cold start, and when fully warmed up, has 35psi at idle and 50-55 psi cruising down the road. I have zero leaks, even with stamped valve covers. If it really bugs you, change the spring. I have the numbers somewhere for both springs, but I can't locate them right now - your Chevy parts counter guy should have them.

As usual John, I appreciate your advice and you're correct. Both oil pumps that have been in the sb have identical height gears. I have put THREE sets of valve covers on the engine, one set on the old cast iron heads that the engine rebuilder put on (Dart Iron Eagles) and two on the replacement Jegs aluminum heads that I installed. I also now use the Moroso gaskets. I have to add that when I had the Iron Eagles on, I had a huge problem of oil infiltration into the intake manifold (an original Winters Foundry intake.) I will never, ever again go to a local machine shop to have an engine rebuilt. I'm much happier with my Mexico-manufactured crate engine, Muchachos! Yee Ha!

 

[Hib Halverson]

I agree with John, in fact, IMO, on the peg cold and 60 psi hot at highway speeds is just what you want. if it's too high when cold, if you're not already using it, switch to a 10W30 oil. Also, with a 40-year old pressure gauge, it's possible it's reading incorrectly. You may want to check oil pressure with a known-good gauge.

As for the valve cover oil leaks, there is not oil under pressure in the heads so I tend to think that's a sealing problem not an oil pressure issue.

 

[Kid_Again]

I agree with John, in fact, IMO, on the peg cold and 60 psi hot at highway speeds is just what you want. if it's too high when cold, if you're not already using it, switch to a 10W30 oil. Also, with a 40-year old pressure gauge, it's possible it's reading incorrectly. You may want to check oil pressure with a known-good gauge.

As for the valve cover oil leaks, there is not oil under pressure in the heads so I tend to think that's a sealing problem not an oil pressure issue.

Thanks Hib!

In fact, my buddy, VNV, had me do exactly what you said and I checked the oil pressure with a new gauge (Notice that I didn't say known good gauge since it was made in the PRC but only used once). The remote gauge and the dash gauge agee to within a few PSI. Time to throw away the Chicom gauge, I suppose:eyerole.

I orginally used 20w50 in this engine (rebuilt .030 original 327) and the needle pegged ALL the time. I should have said that my current oil is a 5w20(30?) and that did bring down the oil pressure somewhat.

The litany goes on. Three sets of valve covers, multiple sets/manufacturers of valve cover gaskets and I still have oil leaks on both sides, at the back. I should add that I have an oil take-off for the supercharger from the back of the engine (where the oil pressure is sensed) and I would have thought that would drop the oil pressure a bit. So the order of oil plumbing in the back, from the block top, is a short length of tubing to give me some working room (3/8 pipe?) to a "t". The oil prssure gauge comes off at the 90* and the riser feeds the supercharger from a 6AN hose. I'll post pictures tonight. When I first installed the take-off for the supercharger, I cranked the engine to see how much oil served the 'charger and a LOT of oil shot out into the coffee can. Forget about measuring volume, there was A LOT OF OIL.

Never thought that I'd complain about too much oil up top.

OK, lets say that I am 100% wrong and the valve covers are fine. Is there any way to have an oil leak, without a water leak, at the back of both heads where they meet the block? I see no evidence of a water leak, there is no oil in the coolant, no coolant in the oil pan. As noted previously, I had oil infiltration into the intake manifold. I've solved that problem. No fouled plugs. The car runs very well with no evidence of an oil leak anywhere else.

I'll appreciate John's part numbers for the standard oil spring since I have the pan pulled anyway.

Since I've had so much problem with this rebuilt engine, it's pushed me in the direction of a new short block since the only thing left is the block - everything else that came with the rebuild is gone - heads, head gasket, intake, carb, water pump, distributor, oil pan, etc. It's the only part left.

Any suggestions on a good place for a decent price on a GMPP 383 sb or even a rebuilt 383 from a reputable high-volume builder?

I'm good for one more try with the existing hardware.

To add insult to injury, this very same engine rebuilder, who came VERY highly recommended to me by a good friend (and still is a good frient) rebuilt my #match 427 and it had too LOW oil pressure. Whereupon I simply bought a zz440. He retired (was out of Mount Holly New Jersey) and it just wasn't worth going after him.

Maybe one of these days we'll meet up but he's now in the hills of Tennesssee somewhere. He pulls that stuff out there and they'll just shoot his ass.

 

[Viet Nam Vett]

Hey My Ching Chow oil Gauge should be good for at least one more use. Just make sure you use eye protection and Duct Tape the plastic lens on so you don't get wacked in the puss if it blows.

 

[JohnZ]

Found it - standard spring is #3814903, 21 coils, 2-7/32" overall length; was still available for $3.80 (list) last time I bought one about six years ago.

 

[Kid_Again]

Found it - standard spring is #3814903, 21 coils, 2-7/32" overall length; was still available for $3.80 (list) last time I bought one about six years ago.

U DA MAN!

Thanks, John!

 

[Viet Nam Vett]

U DA MAN!

Thanks, John!

So this means you get a $100.00 Plus pump for $3.80....

 

[Kid_Again]

So this means you get a $100.00 Plus pump for $3.80....

..you can't go wrong with John or Hib's advice but I'm tellin' ya that this sb has BAD juju AND did i say that i had to swap out the spin-on oil filter adapter because i had oil leaking from there????? I had to replace the oil canister to keep oil in the damn thing

 

[Kid_Again]

Here are two pictures. The first is the oil take off point for the sb at the back of the engine. In my original post, I reversed the order of the hook up but you can see here that the oil pressure gauge is fed off the top whereas the the supercharger is fed off of a 90* fitting which goes into a 6AN hose fitting. Note that there is absolutely NO oil on the top of the engine at the fittings or the back of the intake manifold. All of my oil leaks are coming from the back of the heads, somewhere.

The second shot is of my '66 on Saturday, at the painter's. Doug Ims did a HELL of a job on the new hood and black stinger. He's a craftsman and knows Corvettes inside/out. If you're in South Jersey and want an honest, exceptional body man, send me mail. In my experience, body men are neck and neck with lawyers when evaluating integrity. Sorrry, but that's my experience.

Doug is a one of kind, honest, craftsman.

 

[Hib Halverson]

Thanks Hib!

In fact, my buddy, VNV, had me do exactly what you said and I checked the oil pressure with a new gauge (Notice that I didn't say known good gauge since it was made in the PRC but only used once). The remote gauge and the dash gauge agee to within a few PSI. Time to throw away the Chicom gauge, I suppose:eyerole.

Glad you verified the pressure.

I orginally used 20w50 in this engine (rebuilt .030 original 327) and the needle pegged ALL the time. I should have said that my current oil is a 5w20(30?) and that did bring down the oil pressure somewhat.

You should use a 10W30 not a 5W30 and not a 5W20.

The litany goes on. Three sets of valve covers, multiple sets/manufacturers of valve cover gaskets and I still have oil leaks on both sides, at the back.

Well, I'd first make sure your valve covers have a flat sealing surface. If they're ok, switch to the FelPro high-performance gaskets that are 3/8-thick cork and have a steel reinforcement.

OK, lets say that I am 100% wrong and the valve covers are fine. Is there any way to have an oil leak, without a water leak, at the back of both heads where they meet the block?

Yes. You can have an oil leak right where the block, head and intake maifold meet.[/quote]

(snip)

Any suggestions on a good place for a decent price on a GMPP 383 sb or even a rebuilt 383 from a reputable high-volume builder?

I get most of my GM parts from Tom Henry Racing in Bakerstown PA -ChevroletTom Henry Racing - THR - high-performance Chevrolet sales service parts.

(snip)
Maybe one of these days we'll meet up but he's now in the hills of Tennesssee somewhere. He pulls that stuff out there and they'll just shoot his ass.

A deserved fate, indeed. 12ga 00-buckshot would be my choice.

 

[Kid_Again]

Excellent Hib, thanks! I had no idea that I could have just an oil leak between the head and block. That just raises my suspicion that the block is not straight and the aluminum heads can't flex enough to compensate.

I will definitely ping your recommended website and since I'm in New Jersey, shipping will be less of a problem.

I appreciate your points about the valve covers. The current valve covers are two months old from Jegs (I realize anything can happen with new parts). The previous set is a rigid set of tall aluminum covers that also leaked. Since we've had a LOT of cold weather, I took the time to stone the gasket mating surface to remove any flashing that may have caused a problem. I did stop myself, however, from running a dial indicator along the rails for trueness. I thought that was a BIT much;help.

Thanks for the reference on the valve gaskets.

Since last night, I took John Z's information and measured the oil spring in a known "bad" oil pump and, no surprise, it has the standard pressure oil spring. What VNV is alluding to in a previous email is that I spent a chunk of change to buy the "correct" oil pump for a base engine, on the assumption that I really have a "base engine." I know from you folks that the only difference in the pumps is the spring rate. At this point, while I know that you're correct, I'm trying everything relatively cheap to avoid pulling the engine. I suppose I'm just in denial.

I do know that I received the same block back from the rebuilder - I'm not that dumb (though sometimes I wonder). After all is said and done, I'd like somebody to come with a reasonable explanation of why I have such high oil pressure, especially right at the oil filter pad. According to my reading, the oil pump feeds oil almost directly into the oil filter. If I read a fairly consistent 60-80# at the top of the block, I wonder about the pressure just downstream from the pump.

If you guys in Tennessee find a guy in the woods, dressed in camo and a Midyear patch with a .22-250, dragging a short block intothe woods, I suggest you leave the vicinity.:W

 

[Viet Nam Vett]

If you guys in Tennessee find a guy in the woods, dressed in camo and a Midyear patch with a .22-250, dragging a short block intothe woods, I suggest you leave the vicinity.:W

After just finishing my morning coffee...and reading the above... it was enough to send me running to the out house to relieve my colon....otfl

 

[Hib Halverson]

Excellent Hib, thanks! I had no idea that I could have just an oil leak between the head and block. That just raises my suspicion that the block is not straight and the aluminum heads can't flex enough to compensate.

I would not assume the block is not straight. It would be near impossible to do such a screwed-up job of machinging that the block is dimensionally inaccrate enough to cause an oil leak. Also, the heads will not flex that much.

What you need to look for is a sealing problem at the ends of each intake gasket where it meets the front and rear valley seals. When you find an oil leak near the upper corners of the decks adjuacent to the upper corners of the heads and the corners of the intake manifold, it's gasket sealing that's usually the problem

(snip)I took the time to stone the gasket mating surface to remove any flashing that may have caused a problem. I did stop myself, however, from running a dial indicator along the rails for trueness. I thought that was a BIT much;help.

It's easier to put a straight edge on the gasket surface.

If you guys in Tennessee find a guy in the woods, dressed in camo and a Midyear patch with a .22-250, dragging a short block intothe woods, I suggest you leave the vicinity.:W

I'll keep that in mind.

 

[BigJimZ16]

Is it possible that the block has been decked or the heads shaved enough to cause a misalignment at the intake manifold corners??

 

[Hib Halverson]

I assume the question is about decking the block and milling the heads.

If that's been done to any great extent, yes, it can cause sealing problem and when the dimensions are that much different from stock, the intake manifold will not fit as well.

Typically, this problem crops up when someone mills the heads a significant amount looking for higher compression and if someone has cut the heads by .010 or .020 then maybe there's a problem with that.

If it's a case of just a couple of thou off either just to get the block and head decks straight, unless it's a case of a block and head that's already had that one before, decking and milling for dimensional "straightness" doesn't usually create a problem with sealing.

If you suspect a problem with decking the block or milling the heads the only way to find a good solution is to know how much was cut off each then have a machine shop mill the intake manifold the appropriate amount.

 

[Kid_Again]

OK, perhaps I'll keep the Xanax in the bottle while I go about this AGAIN.

Hib, I take your point about the seal at the end of each intake gasket.

I could swear that I was all over that before but will do it again (besides, I just priced 383 shortblocks :eek ). I think I noted before that I had a LOT of problems with oil infiltration when I had the old iron heads and the stock intake manifold so it's conceivable (perhaps likely) that is the problem.

As for the oil gauge pegging all the time, either I just divide it in half in my mind or cover it with electrical tape.

While I respect (and follow) advice from people like JohnZ and Hib :BOW, I just had to see for myself and ordered a GUARANTEED 300hp oil pump and measured that pump versus my own "bad pump". You guessed it, exactly the same in every dimension/coil count except that the $130 oil pump has a GM logo and part number. Hey, JUST CHECKING, that's all

 

[JohnZ]

While I respect (and follow) advice from people like JohnZ and Hib :BOW, I just had to see for myself and ordered a GUARANTEED 300hp oil pump and measured that pump versus my own "bad pump". You guessed it, exactly the same in every dimension/coil count except that the $130 oil pump has a GM logo and part number. Hey, JUST CHECKING, that's all

Tip on oil pumps - GM made a design change a couple of years ago to save some weight and lightened the casting of the stock SB oil pump (made for them by Melling); the pump in the photo below with the two diagonal ribs in the casting is the "lightweight" pump, and there are reports of failures (broken castings) under "severe" use.

The other photo is the stock SB pump you want - the Melling "Select" #10553 pump, which is the original "bulletproof" GM design used for decades.

 

[Tom Bryant]

I used the good Melling in my engine and it came with a standard spring in the package in case you wanted to change out the higher pressure one factory installed in the pump.