Gauge sensor and Greddy plate thread sizing
 

My issue is I bought a AEM oil pressure gauge. AEM claims there sensor is 1/8 NPT. I also bought a Greddy sandwich plate that allowes you to run multiple sensors. They also claim there ports are 1/8 NPT. Well the AEM gauge only won't thread into the plate. I can only get one turn with ease. But the allen plugs that came with the Greddy plate threads fine. Does anyone what's up? Of course no shops are open for the next few days.

I also went to the parts store to play with a few things and the sensor seems to thread into any 1/8 NPT no issue. Which makes me believe the Greddy plate is off. But all the google searches I did say the Greddy plate is 1/8 NPT.

Did you take the allen plugs to the store and thread them into the 1/8 npt ports?

Yes I did. They did thread into the 1/8 they had on display about two turns. But I'm wanting to see more turns by hand from the gauge before going with it. The allen plugs seem to be a NPS. But not sure. Either was the OP helping me.

I current am sitting here with a 1/8 T tap for my water temp gauge and the oil pressure threads into it fine. So does the allen plug. That's why I'm stumped. But if the allen plug is a NPS it probably would thread into a NPT.

Also the water temp sesor doesn't thread into the Greddy plate. Which makes me think the plate is NPS. But I can't find a male to female fitting for this if this was the case.

All of the aftermarket gauges are supposed to be 1/8 male NPT. Since your gauge threads into the female fittings at the store, it sounds like the issue is with the Greddy part. If the Greddy was NPS, the NPT male should still screw in up to a point where the taper diameter exceeds the straight fitting's diameter. Either the Greddy female threads are damaged or they sent you the wrong thread style.

Can you post a link of the GReddy part you bought? I'm guessing it's the part with a BSP male end and multiple female ports that are supposed to be a combination of NPT and BSP. I'd also assume you tried screwing the AEM pressure gauge into all the different female ports just to be sure.

This is what I have.
Greddy - Oil Filter - Adapter Plate - Nengun Performance

Yea I've tried it everyway. The plate also has a M12x1.25 bolt in it. And I can find a M12x1.25 to 1/8 NPT fitting ($15). Edit. Found it for $7 on Ebay.
http://www.powerflowperformance.com....le-p-2197.html

But was thinking of just tapping it. But need to know if it's ok to tap what I think now is a 1/8 NPS to a 1/8 NPT. Being NPT is taperd you would be going bigger, right?

This is what I have. Part number is back at my shop.
http://i1109.photobucket.com/albums/...dGauges013.jpg

The only thing that can be made out on the instructions which are written in Japanese is where it points to the ports it says 1/8PT. Which now makes me believe it's a BSPT which is mostly used outside the states. I don't think local stores sell the conversion. I'll check.

I bet your right about the BSP thread. You'll be able to thread the car's stock oil pressure dumby sensor into that GReddy female port. There are specialty pipe/plumbing shops online that can sell you a male BSP - female NPT coupler for under $10 so you can screw in the AEM pressure sensor.

Last night I fell across an article from a SR 20 website in which a shop owner verified that the Greddy plate is a BSP. So Summit Racing sells the BSP to NPT adapter. It's actually made by Autometer. Good thing is Summit Racing is down the road from me and they have it in stock.

down the street...lucky you

Yep. Tomorrow night there having a show for two seater sports car.