Hi, I need to know what thread size I need for that hole next to the distributor. For some stupid reason there was no oil pressure switch or that T- fitting for it . what size t fitting do i need? thanks.

 

1/8" pipe (NPT)

 

Thanks guy.

 

WAIT A MINUTE.

1/8 is way too big for the block. It looks like the same size as the oil switch. I need to know the size of that hole on the block.

 

1/8" pipe thread (NPT)

It's about 5/16" - 3/8" OD.

Go to Home Depot. Look at 1/8" pipe things in the plumbing dept.

 

NPT thread sizes are very different than typical SAE nut/bolt sizes. It's a 1/8" NPT thread that will take a 1/8" NPT plug to seal it off.

 

Oh I see.

 

no wait I'm still having problems.

I got 1/8th brass npt. The oil switch/sender whatever the hell it's called screws into the 1/8th npt brass that i got.

So the SWITCH is 1/8 npt not the hole on the block.

Either the engine block's hole was made too small or 1/8 npt is wrong. What else you guys got please.

 

It IS 1/8 npt. The hole and the switch. I've plugged several of these. All you should need is a 1/8 NPT plug of any type. Most all pressure sensors on chevys are NPT as well as aftermarket gauges.

 

the hole above the oil filter looks like 1/8 npt but the distributor one is like less that half the size, is that normal?

 

Are you sure you're looking at the right hole?

 

hmm... appears I've found 2 holes behind the intake.........
There's one thats facing up and there's another one facing the firewall. firewall one has a bigger hole so i guess thats where it goes..... but still... what is that other hole for? (the one facing up)

 

The oil port is facing straight up, and it's right behind the intake.

 

ok So I assume the one facing up is the one I need? Here I'll get you a picture.

 

How bout this, just use a tap with like vaseline and a magnet? Would that be ok?

 

DON'T TAP ANYTHING!!!

Your problem is that the stock little pipe extension piece is broken off in the block. That's why that hole you see there looks like a cast iron hole with a jagged broke-off brass ring down in it.

Get the old brass piece out first. Get one of those SQUARE screw extractors - NOT the fluted twisty looking kind - and back that old piece out of there. You can get em at Sears. Then the new 1/8" pipe piece will thread right in.

Your block is 1/8" pipe. Blee dat. Always has been, since 1955, right up to today. Every last one. Yours is not "special" in any way. Blee dat too. It's mass produced so it's the same as all the rest of em.

You need about a 3" pipe nipple, a 90° elbow with 2 females, (gotta love all the sexual and body part references in pipe thread specs, must have been dreamed up by a real PERVERT) and a new sending unit which it sounds like you already have. All 1/8" pipe. It'll all just screw together and fit. Blee dat. Use the Permatex/Loctite "automotive pipe thread sealer with Teflon" on the threads, it comes on a card hanging in the sealant aisle at your favorite parts store.

 

OK, thanks for saving me. Can't believe I never saw the brass stuck in there..

 

Hmmm well what about this... I'm using a 1/8" and it threads, but it just strips the threading off?? I've gone through two... any ideas? I would make a new thread but I thought this might be easier since his problem was solved.