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I've read that it is common to cut down a stock sbc temp sender to fit the 12X1.5 threaded hole in the head. The sender I have is 1/2 npt and is quite a bit larger than the 12 mm hole. Can I safely remove that much material from the sender without messing anything up? And for my own understanding....what is inside the temp sender?.....How does it work?
I tried turning down an M14x1.5 sender to fit and it ripped in half when I tried to tighten it. Hard to imagine getting a half incher down to that size.
There is just a small electronic thermister, a hard piece of plastic with two electric leads, inside the hollow brass tube.
In fact, I have had a stock one twist in two with just slightly too much torque.
Your best option is to drill out the head and retap it or relocate it to a different spot. Lots of options for that.
Looking through the local salvage yard, I see that some of the 90's gm vehicles have a 3/8 npt sender. Could this be cut down and threaded to 12X1.5? I'd rather modify a sender than the head.
I doubt you can turn down 1/2" to fit in the head. The drivers side brass block plug is the perfect size to drill the interior (allen head) and tap for 1/2" npt.
i tap'd my waterpump for my old camaro and truck and it work'd like a charm....
__________________ cam only lq4 6.0 fox in the 9's in the heat on pump gas thru the mufflers on 26's and with the stock cathederal port heads....BIG THANKS TO TICK PERFORMANCE....
I doubt you can turn down 1/2" to fit in the head. The drivers side brass block plug is the perfect size to drill the interior (allen head) and tap for 1/2" npt.
You are correct. The 1/2" senders won't turn down small enough. I tried an old one I had here and cut completly through it way before it was small enough. I start out with the 3/8 senders and cut them to 12MM.
__________________ 85 Monte Carlo SS, 5.3/4L60E Daily driver--traded
84 Monte Carlo SS, LS3 418, 248/254 615/595 with XER and XE lobes. AFR 225, 1 7/8 Hedman headers from BRP. 200-4R. 9" Ford, 3:50 gears.
You are correct. The 1/2" senders won't turn down small enough. I tried an old one I had here and cut completly through it way before it was small enough. I start out with the 3/8 senders and cut them to 12MM.
Temp sender re-thread 
