Leaderboard

Okay, so I've received various plugs and set screws from both McMaster and Bel-Metric. I ordered 1/8 and 1/4 NPT, 1/8 and 1/4 BSPT, M12 x 1.50 straight thread and M12 x 1.50 tapered thread, and I am still a bit confused! I won't hold you hostage until the end, I'll give you what I THINK the holes were from factory, and then I'll provide some pictures and notes from my "testing". I think the factory balance tube (US market 240Z) came with 2 ea. - 1/8" BSPT and 5 ea. - 1/4" BSPT holes BALANCE TUBE 1/4" BSPT HOLES it was clear to me that 1/4" NPT is too big, couldn't really even get a thread to start, so it makes sense that, 1) One COULD force 1/4" NPT into the holes in the soft aluminum and create some sort of "seal", and 2) a hole that had been "buggered by a previous (or current!) owner could likely be salvaged by tapping to 1/4" NPT. The 1/4" BSPT plugs I have encounter resistance at 1-1/2 turns and are fairly tight at 1-3/4 - 2 turns. This leaves them sticking out farther than I would like for a clean, plugged look as I would like them to be as close to flush as possible. The M12 x 1.50 straight thread, socket set screw I tried fit very loose initially, and threaded quite a ways in (farthest of the three options I tried) before finally hitting resistance. I feel like it MIGHT have finally created a "seal", but not ideal in my opinion. The M12 x 1.50 TAPERED plug encountered resistance at about 3-1/4 turns and was fairly tight at 3-1/2 turns in. This left it pretty close to flush to the surface and provided a good seal and I think this is what I will be using to plug 1/4" BSPT holes. (see pictures below) BALANCE TUBE 1/8" BSPT HOLES it was clear to me that 1/8" NPT is too big, couldn't really even get a thread to start, so it makes sense that, 1) One COULD force 1/8" NPT into the holes in the soft aluminum and create some sort of "seal", and, 2) a hole that had been "buggered" by a previous (or current!) owner could likely be salvaged by tapping to 1/8" NPT. The 1/8" BSPT plugs I have, encounter resistance at 1-1/2 turns and are fairly tight at 2 turns in. This leaves them sticking out more than I would like for a clean look (see pictures below) now I want to experiment with M10 fine thread (both straight and tapered) in the 1/8 BSPT holes INTAKE MANIFOLD WATER HEATING HOLES The outside (inlet and outlet) holes come from the factory with 1/4" BSPT holes Again, the 1/4" BSPT plugs don't thread in very far and sit proud. The M12 x 1.50 TAPER thread plugs thread in farther and sit pretty flush for a clean look. the inner holes (two holes on the inside of each part of the two-part manifold that connects the manifold halves with "bushings" and metal tubing) come from the factory with M16 x 1.50 STRAIGHT thread. I have some M16 x 1.50 straight AND taper plugs coming to try in those holes. I'm now thinking that a straight-threaded plug with a low head and Loctited, may be the ideal ticket for this hole since there is a machined spot to accommodate a bolt head. Heck, any old M16 x 1.50 bolt will work here! Keep in mind that these holes, if not being used (not connected to water lines), can stay open, they do not need to be sealed/plugged, as they will not affect anything other than keeping the intakes warm on initial start-up in cooler weather/climates. I just want to plug them for aesthetic purposes. Here's some pictures to clarify my rambling!

I get a kick out of a big horn sound coming out of a weee Z car. 😎