when i changed the fuel pump i checked the fuel level sending unit it works, i had washed my bearings when the fuel presure regulator went out, put a manual gauge on showed i was getting 12# oil presure, gauge on the dash said normal high about 3/4 way to the right. i replaced the bearings im getting 40 psi on the manual and the dash gauge stays the same. bad instrument cluster?

 

no, ford's oil pressure gauges from about 79 have been basically dummy lights.... they read good and go to one spot if they have 6 psi of oil pressure, and they go to 0 if they have less than 6 psi of oil pressure...

 

I dunno where you are getting your info from, but what you typed is in-correct.

A dummy light is another name for an idiot aka Warning Light. Warning lights are just lenses in the instrument cluster that...if something occurs, glow red.

There were Warning Lights or oil pressure gauges used on ALL these vehicles.

On some of the following vehicles, Warning Lights were standard equipment, the Oil (and Amp gauge) was optional. Some only came with all four gauges.

D4AZ9278A .. Oil Sending Switch / Use with Warning (aka idiot) Lights (Motorcraft SW1311).

Fits: 1957/96 F100/350, F(Super Duty) / 1961/86 Econoline / 1978/96 Bronco / Myriad 1957 and later Passenger Cars.
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E4ZZ9278A .. Oil Sending Switch / Use with Oil Pressure Gauge (Motorcraft SW1547B)

Fits: 1957/89 F100/350, F(Super Duty) / 1966/89 Bronco / 1969/91 Econoline / Myriad 1957/91 Passenger Cars.
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E9SZ9278A .. Oil Sending Switch / Use with Oil Pressure Gauge (Motorcraft SW2220)

Fits: 1990/96 F150/350 & Bronco with V8 (gas) engines.
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E9TZ9278A .. Oil Sending Switch / Use with Oil Pressure Gauge (Motorcraft SW2178A)

Fits: 1990/96 F150/350 & Bronco with the 300 I-6.

 

Doesn't change the truth that the factory gauges do not reflect accurately. They (in conjunction with their accompanying sending units) are "glorified" versions of the warning (idiot) lights. Many folks know this to be true. The OEM gauge will read at a "normal" range and the truth will be that the actual oil pressure is nowhere near acceptable because either the gauge or the sending unit is incapable of discerning the difference between 6 psi and 26 psi.

 

Wich gauges would you use? and how are they installed Grey?.

 

I have Autometer Ultra-lites in an A-post three-gauge cluster (birthday gift from my lovely wife). I wanted those gauges in the truck though. If you are merely concerned about what the true pressure is running at, my recommendation would be to seek out the best gauge your budget can afford. Mechanical gauges use a compression fitting in place of the OEM sending unit, a length of plastic tubing, and another compression fitting into the back of the gauge. The only challenge, if you consider it to be one, is finding a location in the firewall to run the tubing to the interior of the truck. The installation is fairly well lined out in the paperwork that comes with quality gauges. Just be certain you secure the fitting at the back of the gauge... I doubt I need to explain the potential consequences of failing this point. If you are looking for a source for quality gauges, try this site.