I recently bought a '91 Z-28 that is equiped with the 350TPI. And was wondering what the gauge should read when the oil is filled to the correct amount. Thanks.

 

Oil pressure (no direct correlation to level) is usually somewhere around 25-30 idling and 50-55 cruising.

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

 

Its hard to trust a oil pressure gauge. On both of my 3rd gens I have owned it doesn't work at all. Also, it doesn't work on 4 of my 5 friend's cars, just to let you know.

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission
Borg Warner 7.75" 9 Bolt Rear End

Current Mods: LT4 Hot Cam, Comp Cams 1.52:1 Roller Rocker Arms, Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Performance Resource Chip, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET (w/o LT4 cam): 14.32 @ 97.7mph
(corrected for elevation)

7.5" 10 Bolt with 3.42s soon to come!

 

hard to say on my car thats pre-project it held like 10 at idle and 25 on the highway yes.....thats bad!!!! one reson to start project f-body!! im in the works on the below mentioned items in my sig.

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89 firebird formula


356 10.5:1compression
comp cams xe262 cam
performer rpm intake
#1405 edlebrock 600
434 casting completely redone with bronze guides and 202/160 valves 64cc chambers. decked .0005 thousandths
msd 6al
h.e.i. proform 50,000 volt vac. advance ditributor
700r-4 with 3.08 first gear and 3.23 posi 7 5/8 rear end.
b trans shift kit(will kill shifts...suck dong!!)
shorty heddman hedders with custom 3" pipe y-pipe back(no damn cat!) with 40 series flowmaster!

future mods: 406 roller REALLY REALLY REALLY RADICAL!!!!!

 

When I put my NOS kit in I also put a fuel pressure and new oil guage in on the pillar and my stock guage was off by at least 10 psi if not more but I have a high volume pump and am running 29-33 idle and 50-75 high rpm

 

I recently saw a Tech article in VETTE or CORVETTE FEVER mag (I forgot which) and the author, Chris Petris, said the normal pressure should be 25 psi at idle, 200 F, synthetic oil (weight not given.) Anything 10 psi or higher at hot idle is okay though.

The old rule of thumb is 10 psi for each 1000 rpms the engine turns at speed.

Jake

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

 

My 1991 RS runs 45 psi cold and 30 psi hot at idle using 10W30 synthetic. At least when the d#$n guage works
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