Drill and tap the head for stock 65 temp sender? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**Clyde65** · 10-16-2020, 10:41 AM

Anyone did this? Info please
Posted via Mobile Device

**mongocanfly** · 10-16-2020, 12:06 PM

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...

**Captainfab** · 10-16-2020, 09:26 PM

This is another option.

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

ls1nova71 · 10-17-2020, 09:26 PM

Quote:

Originally Posted by Captainfab

This is another option.

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

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.

**Captainfab** · 10-19-2020, 08:15 PM

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

Quote:

Originally Posted by ls1nova71

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.

**mongocanfly** · 10-16-2020, 11:08 PM

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

LS short box · 10-19-2020, 09:31 PM

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.

**A1971Blazer** · 10-20-2020, 07:15 AM

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
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Name: IMG_0945.jpg
Views: 199
Size: 21.8 KB

**Jason Banks** · 10-25-2020, 07:28 PM

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.

10-16-2020, 10:41 AM	#1
Clyde65 1965 Chevy C10, 2005 4.8L/4l60 Join Date: Aug 2004 Location: DFW Texas Posts: 8,546	Drill and tap the head for stock 65 temp sender? Anyone did this? Info please Posted via Mobile Device

10-16-2020, 12:06 PM	#2
mongocanfly Post Whore Join Date: May 2015 Location: Alabama Posts: 14,670	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... __________________ Mongo...aka Greg RIP Dad RIP Jesse 1981 C30 LQ9 NV4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598 Mongos AD- LS3 TR6060...http://67-72chevytrucks.com/vboard/s...34#post8522334 Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563 2023 Chevy Z71..daily driver

10-16-2020, 09:26 PM	#3
Captainfab 60-66 Nut Join Date: Mar 2007 Location: Coeur d'Alene, Idaho Posts: 23,252	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 __________________ Power Steering Box Adapter Plates For Sale HERE Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE Hydroboost Mounting Plates HERE

10-16-2020, 11:08 PM	#6
mongocanfly Post Whore Join Date: May 2015 Location: Alabama Posts: 14,670	Re: Drill and tap the head for stock 65 temp sender? I looked for that post Capt... and couldn't find it... __________________ Mongo...aka Greg RIP Dad RIP Jesse 1981 C30 LQ9 NV4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598 Mongos AD- LS3 TR6060...http://67-72chevytrucks.com/vboard/s...34#post8522334 Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563 2023 Chevy Z71..daily driver

10-19-2020, 09:31 PM	#7
LS short box Registered User Join Date: Jun 2015 Location: Carlos MN Posts: 2,131	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.

10-20-2020, 07:15 AM	#8
A1971Blazer Senior Member Join Date: Nov 2013 Location: East Tennessee Posts: 2,198	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 __________________ 1967 C10 Step side 1968 C10 Step side 1970 Chevrolet K/5 Blazer 1972 Chevrolet K/5 Blazer .............

10-25-2020, 07:28 PM	#9
Jason Banks Senior Member Join Date: Dec 1999 Location: TX Posts: 1,623	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.

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