Two Gauge Questions

[El_Crnicero]

1.) I have a new oil pressure gauge that came with a new sending unit. It is much bigger than the one that is on the back of the block by the dizzy. I have heard that there is another place to put it near the oil filter. The only place I found on my 71's block didn't look light it would work? There is no existing plug but it seems to have threads there? Also I can't put it on the heads because I am running camel humps and they have no access holes. Here are some pics. Any suggestions?

2.) as per the wiring diagram there are two fuel wires, one that just says fuel gauge and the color is tan, and one is the fuel feed Pink. what are the differences?
Is fuel feed to the sending unit? and Gauge just power?

Thanks for your help.

[Legolas894]

I think the spot behind the distributor is 1/8" NPT. You could put a 1/8" to 1/4" adapter and use the same spot. If you have the idiot light pressure switch (like I did), you could also use a 1/8" nipple to a 1/8" tee. Put the old pressure switch in the tee and then you still use the 1/8 to 1/4 adapter for the new sender.

I just did this a few weeks ago. I used new copper tubing in place of the nylon tubing that came with mine. You might have an electrical sender so it wouldn't matter.

[El_Crnicero]

this one is an electic sending unit. no lines. just a wire from the top of the knurl to the back of the gauge. plus the part that threads is like 1/2" npt? Im pretty sure its that big.

Thanks

[chevy_mike]

Wow those are some big threads for a oil sending unit. Can't say I have ever seen them that big. Typically they are 1/8" NPT.

NAPA (and others) sell adapters that would allow you to step it up. Might take two to go that large.

Most of these type sender won't fit next to the distributor without putting some 45 or 90* fitting. The port above the oil filter works too but it gives you a reading at the filter output, not at the top end of the engine like the one up by the dist. would.

Good luck.

[Green Machine]

Some blocks have a 1/8 npt plug into the oil galley right above the timing chain cover, might want to check there.

[mr48chev]

Napa or other places sell the adapter/reducer. As Legolas894 said you could also put in a T and run the idiot light if the truck has one.

I'm not sure on the wiring for the sending unit and gage, you will have to consult the instructions there.

[fixit-p]

Originally Posted by El_Crnicero

this one is an electic sending unit. no lines. just a wire from the top of the knurl to the back of the gauge. plus the part that threads is like 1/2" npt? Im pretty sure its that big.
Thanks

From the pic it looks like 1/4" npt, when you say it's 1/2" npt are you going by the O.D. because 1/4" npt actualy measures .540" on the major O.D. (diameter of 1/4" pipe)

[El_Crnicero]

So it sounds like it might be alwright to just run some reducers to get it down to size?
Hopefully I can get this done soon, I just put a new audio system, and cam & lifters in it. Im ready to go for a drive....

[airdale94]

There is no oil press. port in any head, pressurized oil passes through the push rods. There is no power at the fuel sending unit in the tank just ground. The float increases resistance (ohms) and tells the gauge E or F. Tan is the sending unit wire.
There are complete wiring diagrams in the FAQ section.

[Jacfourteen]

Originally Posted by fixit-p

From the pic it looks like 1/4" npt, when you say it's 1/2" npt are you going by the O.D. because 1/4" npt actualy measures .540" on the major O.D. (diameter of 1/4" pipe)

x2