307 Oil pressure & temp sending units

[Flatbed136]

Please bare with me as I explain this as I'm a green horn.

As you can see from the picture, there is currently an after market set of guages.

I would like to hook the factory gauges back up.

The guy I got the truck from told me I had 327 heads. I ran the casting numbers from the head on the drivers side and it shows it is a 350.

Casting number is 333882. I have not looked at the other one.

What size threads or sending unit will I need for the temp guage?

The block casting numbers show it is either a 307 or 350. Was told since it has a thin or smaller harmonic balancer than more than likely it is a 307.

What size threads or sending unit will I need for the oil pressure?

The oil pressure is currently located by the distributor with a plastic line.

Any help and information would be greatly appreciated.

Thanks for your help.

[oldgold70c10]

The threads in the block for the oil pressure gauge are 1/8" pipe thread. No sender is used with the stock gauges, but an adapter to go from 1/8" pipe to the small compression size for the pipe that goes to the gauge. The plastic line may be the same size as the factory steel oil pipe, so you might try unscrewing it from the back of the aftermarket gauge and see if it will fit the stock gauge. If not, you can find a stock oil pipe on the parts board from a parts truck.

The temp sender is 3/8" pipe thread. You can get one at the auto parts store, just tell you want one for gauges.

In either case, you may want to find out why the factory gauges were unhooked. The temp gauge and sender, in particular. Check the wiring, and make sure it isn't too badly burned or hacked up.

[Flatbed136]

I'll look and see why.

I know the P/O had a big block in it at one time. I'm not sure if that would have anything to do with it.

Thanks oldgold.

[Flatbed136]

It appears they just cut the original oil line right at where the little plug is in the firewall.

I got the dash out and there was still a long piece of the original line.

The original temp gauge appears like it never had anything hooked up to it.

It has a white strip across where I would assume the hole would be to attach the line.

Does this sound correct?

Thanks again

[oldgold70c10]

The temp gauge should be connected to the printed circuit via a couple of 5/16" or 3/8" nuts. The white strip is a resistor that helps the temp gauge work. Check the plug that connects to the cluster. Do any of the wires look cut.
The wire that went to the sender in the engine bay is a green one. It will be run from the engine wiring harness plug on the firewall.

[Flatbed136]

Thanks again Oldgold.

I'll trace the wires as you describe and see what I come up with it.

I'm sure I'll have more questions.

[oldgold70c10]

This will help you trace:
http://67-72chevytrucks.com/vboard/s...d.php?t=185856