How accurate are your old rally cluster gauges?

[MikeyM]

Hey All,

Happy Friday. I’m asking because I just got my rally dash cluster back online, except for the fuel gauge. They seem to be working; my temperature runs at about 160 to 170 so I am going to confirm that by putting in a 180° thermostat, this weekend. My concern is the oil pressure gauge. When cold, oil pressure is seemingly where it should be. When warm, however, oil pressure seems fine at speed, say above 1500/2000 RPM. The gauge usually registers around 40 to 60 psi, somewhere around there. However, at idle, the pressure drops to below 20 psi, at least according to the gauge. I have read a couple posts of some type of spring?? In the oil pump that can be changed to raise oil pressure? I have a new sending unit installed, but I was going to pick up a manual, external gauge to test and confirm. Any thoughts or input you guys have would be greatly appreciated.

Thanks,
Mikey.

 

[RR Fan Dan]

20 pounds at idle is fine

 

[R413]

Completely mormal, worry about something else.

 

[Jerry Hall]

Redline gauges did my Superbird cluster 25 years ago and it still works just like it did the day I installed it. My oil pressure reads just slightly over 20 lbs at idle hot and 35 to 38 lbs hot above 1500 rpms. It's a standard pressure oil pump. I prefer that on a stock build, because there is no need to have a larger capacity oil pan due to a high volume/pressure oil pump. The only change i made in the build that wasn't stock to my car was to go with a 6 pak spec cam.

 

[MikeyM]

Sweet. Thanks for the info. Yeah, I just got a little worried because the gauge seemed to show about 10 psi. So I don’t know if the gauge is off a little bit or if my oil pump might be weak. It idles fine, no weird noises stays cool. I’m running mobile 115 W 50 so hopefully the gauge is a little off. I think I read somewhere that there’s a way to calibrate these things, but I don’t know how.

Mikey

 

[Jerry Hall]

Sweet. Thanks for the info. Yeah, I just got a little worried because the gauge seemed to show about 10 psi. So I don’t know if the gauge is off a little bit or if my oil pump might be weak. It idles fine, no weird noises stays cool. I’m running mobile 115 W 50 so hopefully the gauge is a little off. I think I read somewhere that there’s a way to calibrate these things, but I don’t know how.

Mikey

Flat tapplet cam? Does Mobile 1 15W 50 have zinc or are you using an additive? I'm using Valvoline VR 1 20W 50.

 

[Kern Dog]

If you've ever taken these gauges apart, you'll wonder why you even trust them. They are extremely simple and from even a layman's view, they are merely "guidelines" as to what is going on. Tachometers are often notoriously slow so while you rev past 6000 rpms, the tach may show 5000, 5500 because it is lagging behind.
The guts of these gauges can be bent, stretched and tweaked a bit to give different readings so personally, I don't put 100% trust in them. I would suspect that you could swap entire instrument panels from car to car, changing nothing else and get different readings.
Speedometers are mechanical so those can be adjusted for accuracy with the transmission pinion gear.
Stock fuel sending units have a specific operating range that NO aftermarket sending unit can duplicate. Aftermarket fuel sending units have a reputation for delivering an inconsistent reading at the gauge. Sometimes the tank is full and the gauge will only go to 3/4 tank. When the tank is empty, the needle often rests below the E line.

 

[MWbirdLOVER70]

Completely mormal, worry about something else.

X2

 

[MWbirdLOVER70]

Flat tapplet cam? Does Mobile 1 15W 50 have zinc or are you using an additive? I'm using Valvoline VR 1 20W 50.

VR1 here and same weight. Really good stuff

 

[MikeyM]

Thanks all.

Jerry - yessir. Mobil 1 has pretty high zinc levels. Not quite as much as the Amsoil Z-Rod but it’s still up there. I’ve been using the same oil in my super high performance (kidding) 100HP VW type4 air cooled engine in our bus since I built it a few years ago and so far we’ve put about 15k freeway miles at between 3-4K RPM consistently and no issues.

Kerndog, thanks for the info. I will pick up a manual gauge and see where I’m at.

Thanks again,
Mikey