Drill and tap the head for stock 65 temp sender?
 

Anyone did this? Info please
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Re: Drill and tap the head for stock 65 temp sender?
 

Yep...I've done that to all mine...I've done both 3/8 & 1/2 npt...
3/8 npt was for a elec sender ,,the 1/2 npt was for a mech sender...
I'm not sure what size your 65 has...
i drill and tap the pass side head at the rear
I remove the plug that's there...I've done them in the truck, but prefer to do it on a engine stand...that way i can tilt the engine at a angle...after drilling i take a shop vac and stick over the hole to suck out any stray shavings...then on the tap i put grease in the flutes to catch the tap shavings...

Re: Drill and tap the head for stock 65 temp sender?
 

This is another option.

http://www.67-72chevytrucks.com/vboa...d.php?t=726700

Re: Drill and tap the head for stock 65 temp sender?
 

I looked for that post Capt... and couldn't find it...

Re: Drill and tap the head for stock 65 temp sender?
 

That works on the newer trucks that had a smaller sender, but if you try it on a 67-72 sender you'll hit the innards before you get it small enough to thread in the head of an LS. :(

Re: Drill and tap the head for stock 65 temp sender?
 

So the LS heads have a hole smaller than 3/8" NPT?

Re: Drill and tap the head for stock 65 temp sender?
 

Yeah it is smaller. If you are running aftermarket gauges like Autometer they can supply a brass adapter that screws in the stock LS port on the cylinder head. Works well.
On some my older LS swaps I did drill and tap the head. The only thing I would add to above is put some grease on the drill bit to catch the drill shavings.
Also as you tap the new drilled hole, tap it a bit and check with the sensor if it's deep enough. Kind of sneak up on the depth of the threads since it's pipe threads.

Re: Drill and tap the head for stock 65 temp sender?
 

I have been doing the modification of the factory sender for the 67-72
The stock sender is ½-NPT and there is enough material to turn and thread it to ⅜-NPT
Unfortunately the LS style sender is 12mm and there just isn't material enough to machine it down that small
Here is a cut away of the stock sender
Attachment 2056050

Re: Drill and tap the head for stock 65 temp sender?
 

I'm a little late getting here but has anyone tried the Classic Instruments SN12MM

It's supposed to be a 12mm sender that will work with older gauges.