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914World.com _ 914World Garage _ CHT sensor block off
Posted by: bbrock Dec 6 2020, 04:33 PM
I'm running carbs on my 73 2.0L so don't need the CHT sensor for D-Jet but thought I would block off the hole in the head to keep it from filling with crap. I was planning to just screw my old sensor in but it is so far MIA. My second thought is to source an aluminum bolt from McMaster Carr but not sure of size. Looks like probably M8x1.25 from what I've been able to find but would like to confirm and not sure of depth. Unfortunately I installed the heads and tins before thinking about this so it isn't very accessible.
Would an M8x16mm aluminum bolt work there and does anyone see any problem with doing that?
I know I'm probably overthinking this but that's kind of my thing. 
Posted by: bdstone914 Dec 6 2020, 04:49 PM
@http://www.914world.com/bbs2/index.php?showuser=20845
I'm running carbs on my 73 2.0L so don't need the CHT sensor for D-Jet but thought I would block off the hole in the head to keep it from filling with crap. I was planning to just screw my old sensor in but it is so far MIA. My second thought is to source an aluminum bolt from McMaster Carr but not sure of size. Looks like probably M8x1.25 from what I've been able to find but would like to confirm and not sure of depth. Unfortunately I installed the heads and tins before thinking about this so it isn't very accessible.
Would an M8x16mm aluminum bolt work there and does anyone see any problem with doing that?
I know I'm probably overthinking this but that's kind of my thing.
It is blind hole so no need to put anything it it. Just plug the hole in the tin where the gromett installs.
Posted by: Superhawk996 Dec 6 2020, 06:20 PM
@http://www.914world.com/bbs2/index.php?showuser=20845 since I know you won't be happy leaving the hole unplugged 
M10 x 1.0 is the thread form
Sensor is about 9mm long.
Hole in the head is 15mm deep but you don't want to go to bottom, I doubt the last couple threads are fully formed.
Sensor is steel. No need for Aluminum bolt. Just use a little anti-seize on it and you won't have to worry about corrosion. Aluminum on aluminum threads are prone to galling too so you'd want to use a little anti-seize there too anyway.
Agree with @http://www.914world.com/bbs2/index.php?showuser=1319 -- plug the tin hole. That is actually the more important part.
Posted by: bbrock Dec 6 2020, 06:53 PM
Thanks both. Yeah, I know it is a blind hole but I also know how crudded up these engine get if there is an oil leak. Figured I be preemptive for a change. I also may have a plan for that hole for a future project so would like to keep it clean. Might be a moot point though. Not finding an M10x1.0 cap screw in aluminum. Brass, but not Al. I've got one more box I can search for the old sensor and if I don't find it, I think I'll call it good.
I do have a grommet coming for the tin.
And yes @http://www.914world.com/bbs2/index.php?showuser=22428 , you know me well. 
Thanks for the help.
Posted by: Olympic 914 Dec 7 2020, 08:27 AM
You could get one of Brads CHT sensor spacers from 914LTD
https://914ltd.com/product/porsche-914-4-cylinder-head-temperature-sensor-extension/
Posted by: Superhawk996 Dec 7 2020, 10:08 AM
@http://www.914world.com/bbs2/index.php?showuser=20845
I know I'm anal about wanting weight reduction. Sheesh you're hardcore by rejecting brass vs. aluminum!
Posted by: bbrock Dec 7 2020, 10:17 AM
@http://www.914world.com/bbs2/index.php?showuser=20845
I know I'm anal about wanting weight reduction. Sheesh you're hardcore by rejecting brass vs. aluminum!
I didn't think brass played nice with aluminum. Also wasn't sure about the expansion properties. Paranoid about cracking a head putting the wrong thing in there and not knowing enough about what I am doing. I'd rather just leave the hole open and not be able to enjoy driving the car known it might be filling with gunk than crack a head.
@http://www.914world.com/bbs2/index.php?showuser=13287 thanks for the tip on the extension. I also thought about just buying a CHT to screw in their but realized that my cheapness is bigger than my OCD
Posted by: bdstone914 Dec 7 2020, 10:28 AM
@http://www.914world.com/bbs2/index.php?showuser=20845
I know I'm anal about wanting weight reduction. Sheesh you're hardcore by rejecting brass vs. aluminum!
Whats wrong with a steel bolt? All the other hardware that screws into the head is steel.
Posted by: bbrock Dec 7 2020, 10:43 AM
@http://www.914world.com/bbs2/index.php?showuser=20845
I know I'm anal about wanting weight reduction. Sheesh you're hardcore by rejecting brass vs. aluminum!
Whats wrong with a steel bolt? All the other hardware that screws into the head is steel.
Good point! Didn't think about all the studs and sheet metal screws in the things. My anal retentiveness caught a lucky break today. Thanks!
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