81fixerupper

I am redoing the top end on my 81 (new cam, vortec heads) and will replace my oil pump as a precaution. I was wondering should I go with stock or high volume oil pump, as I think I recall hearing arguments go both ways? By the way I don't know how many miles are on the engine for sure or the oil pressure, just that it was running well and not smoking when I tore it down.

norvalwilhelm

I'm a fan of high volumn oil pumps. I like to see 40-50 pounds hot idling. I also like seeing 60 hot running down the road.
It bothers me to see 15-20 at idle even if it is enough.

S489

whichever you choose, deburr the gears and set the endplay to spec (can't remember range off hand). factory should be fine . . .

jackson

Lotsa opinions.

Most HV pumps' volume = stock + 25%

Sit on the fence & split the diff.

Melling p/n 10552 has the good strong casting, hi-grade gears, shafts extended into cover, uses a bolt-on screen, under $100 ... but volume = stock + 10%

rclinton

From recommendations on this forum I purchased the 10552 pump, $60 special order from Autozone. I selected that pump after discussions metionintg the "select" melling pumps having better casings and gears, split the difference and went with the 10% over stock.

a1sensei

Without knowing there was any controversy, I rebuilt mine with the Federal-Mogal kit that contained the Melling HV pump. I get 80 psi all the time except when idling on the hottest days, when it may drop to 65. I have driven the car every day like that for two years now with no problems. Just my $.02. God bless, Sensei

thrilher

i like the 10% over..that is a feature that should be 30 yrs old but i'd guess its relatively new...good deal!!

nastee383

I put a Moroso std. volume pump/pickup in my 396 I just finished. It has 30 - 40 psi at idle and 65 - 70 at cruise with Mobil1 5w30. My understanding is std. volume uses less pwr to turn and is less stressful on the distributor gear.

vetteblewbyu

Only so much oil can go through the engine before the bypass kicks in. If you have decent bearing clearances, a standard volume is more than enough. The rest is just wasted power.

LT1driver

wonder why chevy didn't install them, food for thought

MotorHead

I am putting the 10552 pump in my new 427ci small block. I usually run the Z28 pump which is the 55A pump but this motor is going to make some power

Thmprr

If you want to follow the advice from an Engine Builder with 35yrs experience, don't fit them to street driven engines.
They can harm your engine owing to the bypassed oil causes air bubbles to form in the oil, thereby achieving less bearing oil film strength.
Chevrolet knew exactly what they were doing when they designed the oil system on the SBC.
The old adage holds true, 10psi per 1000rpm is completely adequate. HV pumps also cause premature distributor gear wear and in some cases broken drive tangs if the engine is "buzzed" when cold.
Leave them to the drag and circle track guys who need them for high rpm use.

MotorHead

How about this motor, do you think it would be fine with a stock pump ?

- AFR 227cc Eliminator heads 2.100" intake valves ( flow ~ 330cfm )
- Jesel shaft mount rockers 1.6 ratio
- Vic Jr intake port matched by AFR to heads
- Motown block 4.125" bore, 350 mains, with splayed steel caps
- Eagle 4340 4 inch crank with 350 mains
- Eagle 4340 stroker H beam rods with ARP 2000 bolts
- Mahle forged pistons 10.5:1 with the 65cc heads
- Comp Cams XR286R solid roller small base circle billet cam 248/254 deg @ .050 and .614" in / .620" lift
- 825 Drag Race Demon ( flows 975cfm )

chvet73

The guy who I use for machine shop work said do not use a high volume pump. I'm sure he has forgotten more than I'll ever know about engines. I have tremendous respect for his opinions.
His reason for not using one was that the high flow can make rings more difficult to seat. I followed his advice and mine works well with a standard pump.

7T1vette

The choice of oil/synthetic and filter are more important to the engine than additional [and unnecessary] oil pressure. Unless you are going 'dry sump' and racing-only, forget the high volume pump....it will just waste horsepower and add heat/.

noonie

I am a firm believer in having lots of oil.
I use a Melling 10555 pump with the stock 70 lb relief valve spring. I temporarily had a Melling M55HV pump but decided to go with a 7 qt pan and the better pump for a few extra bucks.

Some may think this is overkill, but it is a stock L48 with the oil galley plugs drilled to spray the timing chain and the dist housing milled to spray the cam/dist gear. That is my only real requrement for more oil flow, but here in the deep south the added flow and capacity certainly won't hurt for temperature reasons alone.

The 10555 has the original thick mounting casting with a steel sleeve and uses a 3/4" intake instead of 5/8".

Also is a quote out of Mellings catalogue dispelling some of the myths of HV pumps.

Fonz69

Had one in my 540 and the distributor gear did wear more than it should of.

I switched to a standard volume one that came with my steff's oil pan, I have not got a chance to see how well it works yet but hope for the best

ShinodaVette

Fact: On your '81, the high volume pump will not clear your factory oil pan. Ask me how I know.

capevettes

noonie

If your accurate oil pressure guage reads less than 70 PSI, then you are not bypassing the oil (going over the relief valve).

If your are over 70psi when the engine is at operaing temp, thern the most common cause is the oil viscosity being too high (too thick).
Don't blame the oil pump.

As far as wasted power, increased pressure needs more power not the flow, read Mellings quote or better yet go to their website and read the tech section for oil pump basics.