chris1roc

I was just wondering is it supposed to go just above that line before the red line at about 16 or 17? Is that too low? i have 110,000 miles do I need a new oil pump?

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88 iroc
305 tpi
k&n, flowmaster, ADS chip
home made ram air
removed smog pump
ASCD big block hood

RB83L69

These cars usually run at 20-30 psi idle, and 50-55 cruising.

If yours reads way low, but the engine doesn't seem to be in low oil pressure distress (noisy, severely blackened & burnt-smelling oil, etc.) then your sending unit is probably bad. Try replacing it; it's cheap and easy and usually fixes the problem. If it still reads way low, especially if it reads normally when cold but falls way off when it heats up, it's time to start thinking fast about where your next motor is going to come from.

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"So many Mustangs, so little time..."
ICON Motorsports

ihateallmustangs

so where is the sending unit for the oil pressure gauge then?....

Greg

As the engine wears and the bearing clearances increase the oil pressure will read lower. You can put some heavier weight oil in like 10W40 or 15W40.

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'89 Formula 383 TPI

MrF-body

ihateallmustangs, very cool name! the sending unit is on the rear drivers side of the engine(when looking at it from the front of the car) it is screwed into a tube beside the distributor. i think it only has one wire going to it.

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have a beat to hell 87 GTA 305ci 700r4
t-tops,recaro,honeycomb wheels,digital dash
paid $600 at a junkyard for it (i had to save it)

Stormshadow GTA

[QUOTE]Originally posted by RB83L69:
[B]These cars usually run at 20-30 psi idle, and 50-55 cruising.

If yours reads way low, but the engine doesn't seem to be in low oil pressure distress (noisy, severely blackened & burnt-smelling oil, etc.) then your sending unit is probably bad. Try replacing it; it's cheap and easy and usually fixes the problem. If it still reads way low, especially if it reads normally when cold but falls way off when it heats up, it's time to start thinking fast about where your next motor is going to come from.

What do you mean look for a next motor.My oil pressure reads fine when cold but when im heated up it drops but it doesn't go past the redline it stays just above it.What do you think is wrong

82camaro

10 psi per 1000 rpm is all you need. 16 at idle is fine. If you don't have any engine noise, don't worry about it. I've seen engines with 5 at idle run for years and years.

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82 camaro--original steering wheel, brake/gas pedals, seats--everything else modified
82camaro

Ed Maher

F-body oil pressure guages are notoriously inaccaurate. If you're not using a known good mech. guage, don't pay any attention to the dash guage.
Ex. My oil pressure reads 30ish when cold and drops to dead 0 at idle when hot. I am sure i still have oil pressure as i would imagine my lifters would start clattering if left with no oil for 10 minutes waiting at these damn noVA red lights.
...ed

JakeJr

I read a Tech Reply article recently in one of the mags that said a Vette TPI engine has a factory installed high volume pump and should give 25 psi, hot,at idle with synthetic oil (weight not given though).

Response went on to say that he'd seen a few Vette engines that had the wrong - passenger car standard volume - pump installed that gave only 10/15 psi at idle.

I'd never read that before and I know there's been a lot of back and forth on the advisability of using a HV pump with a 5 quart pan.

I'd say that the F body cars should have the same setup since the engines are so similar.

I cut a groove in my distributor housing (to direct pressurized oil at the distributor/cam gears) and drilled a hole in the front of the block to direct oil to my timing chain so I had to shim my pump's (HV/HP) pump to raise the pressure.

Jake

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1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9

RB83L69

No factory motor has a "high-volume" pump. There is no such thing as a factory "high volume" pump for a small block at all. The Vette, just like our cars, does have a high pressure pump however. The original SBC pump, replaced by the M55, had a pressure spring that producd about 30-35 psi at cruise RPM where the one that is replaced by the M55A has a 50 psi spring. The delivery capacity, as determined by the gears in the pump, is identical between the old 30 psi pump and the 50 psi pump.

A "high volume" pump (such as the M55-HVS) is nothing more or less than a stock big-block pump, with a special screen to fit a small block pan's depth. If you are willing to massage the pickup a little to set its relation to the pan depth, you can even take a stock BBC pump out of the box and stick it in your SBC. The M77 was in fact what we all used for years before the M55-HVS was invented.

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"So many Mustangs, so little time..."
ICON Motorsports

berlinetta84

if there is supposed to be about 50psi cruising, then how come does my 1984 305 with 81000 miles make about 20-25 at idle warm but when cruising it goes up to 30-35...is that a sign of a bad oil pump? or was the pump different back then and thats normal?

RB83L69

You've probably got the lower pressure bypass spring in your pump. 30-35 is what small blocks mostly had back in the 60s and 70s anyway; if that's what it has always had, it's nothing to worry about. Your pump is the regular M55, or equivalent.

Now if it was 60 cold, and then 5 at idle and 30 cruising when hot with lots of ticking that got worse as it warmed up, that would indicate a problem. But 20-25 at a hot idle is a good sign.

Maybe somebody has changed out the pump at some point in the car's life?

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"So many Mustangs, so little time..."
ICON Motorsports

Stormshadow GTA

My pressure gauge is in Kpa How do i know what psi i have by reading kpa

rusty Z

Chis1roc, my '85 Z-28 (w/ 146,000) had the same thing happen last summer. In the ten years I 've owned my car the oil pressure has been consistant. I was driving it on a normal summer day, not too hot, and I watched my oil gauge drop a little at each stop light. When I gassed it the guage would raise, no biggie. Finally while sitting in a drive thru the guage bottomed out, oh sh**! I turned the car off immediatly. I checked the vitals, all good. The point of my horror story is that it was my sending unit! What a scare! Just thought I'd share this story with the board.

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'85 Z28 Copper/ Gold, LG4
dual snorkel w/ ram air, Accel Cap Rotor and 8MM wires, Edelbrock Headers, Catco Cat, Flowmaster 80 series
American Racing Wheels. 350 crate in the future.

stallone

Stormshadow GTA: Look the conversion table at this site:

http://www.gameco.com.au/tech/convtbl.htm

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trans-am 91 3.08 posi 5.0 lb9 5 speed stock

[This message has been edited by stallone (edited February 14, 2001).]

JakeJr

Interesting that you would say that.

Chris Petris of Corvette Fever magazine doesn't agree though nor does GM. In the Feb 2001 issue of Corvette Fever magazine, beginning on page 80, he specifically says the C4 Corvette pump is high volume and that he's occasionally found a standard volume pump on engines after a major rebuild and that the standard volume pump is the incorrect pump.

GM part # 14044872 is the High Volume pump for the small block which has 1.5" long gears and four bolts holding the cover. Standard volume pump have 1.2" long gears So there is a factory "high volume" pump for the small block.

GM part # 10051105 is the Big Block version of the High Volume pump and its cover plate has 5 bolts. The LS-7's heavy-duty pump gears are 1.3" long. I'm using a Big Block 5 bolt pump on Steve's 434 that I'm building.

A couple of weeks ago I bought and installed a High Volume Melling M55HV (not HVS) oil pump from O'Reilly's Auto Parts which showed up on their computer screen for the 86 Vette engine. I installed it on a 355 I built for a guy to go in his 86 Vette. The pump came with the High Pressure spring installed, but had the standard pressure spring in a clear plastic bag in the box for optional use.

Jake

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1986 Corvette Coupe, 415 CID, Edelbrock 6073s, ZZ9

[This message has been edited by JakeJr (edited February 15, 2001).]