Coolant sensor thread pitches, locations
Thread Starter
Racer
Joined: Oct 2004
Posts: 286
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From: Washington DC
Coolant sensor thread pitches, locations
Hey all - quick question. I've got an '86 that's a bit of a frankenstein; long story short, it now has an older set of Edelbrock performer heads (these were given to me by my engine builder.) I've got the engine installed and 90% hooked up but have hit a snag w/the coolant sensors in the heads. A few questions:
a) what thread pitch are the original sensors in an '86?
b) the sensor in the intake manifold, I believe, is for the ECM. The one on the driver's side head is the fan switch, I believe - what does the sensor in the RH head do? The instrument panel?
c) the threads in the Edelbrock heads are 1/2" NPT, I believe. The goal here is to adapt the old sensors to the new heads, but I can't seem to find any adapters that do so; I suspected the sensors were 3/8", but when I try to thread the sensor into a 3/8 to 1/2 adapter, the sensor's threads seem just a bit too wide to thread in.
Any suggestions here are greatly appreciated. Cheers.
a) what thread pitch are the original sensors in an '86?
b) the sensor in the intake manifold, I believe, is for the ECM. The one on the driver's side head is the fan switch, I believe - what does the sensor in the RH head do? The instrument panel?
c) the threads in the Edelbrock heads are 1/2" NPT, I believe. The goal here is to adapt the old sensors to the new heads, but I can't seem to find any adapters that do so; I suspected the sensors were 3/8", but when I try to thread the sensor into a 3/8 to 1/2 adapter, the sensor's threads seem just a bit too wide to thread in.
Any suggestions here are greatly appreciated. Cheers.
Team Owner
Joined: Sep 2003
Posts: 25,386
Likes: 2,737
Hey all - quick question. I've got an '86 that's a bit of a frankenstein; long story short, it now has an older set of Edelbrock performer heads (these were given to me by my engine builder.) I've got the engine installed and 90% hooked up but have hit a snag w/the coolant sensors in the heads. A few questions:
a) what thread pitch are the original sensors in an '86?
b) the sensor in the intake manifold, I believe, is for the ECM. The one on the driver's side head is the fan switch, I believe - what does the sensor in the RH head do? The instrument panel?
c) the threads in the Edelbrock heads are 1/2" NPT, I believe. The goal here is to adapt the old sensors to the new heads, but I can't seem to find any adapters that do so; I suspected the sensors were 3/8", but when I try to thread the sensor into a 3/8 to 1/2 adapter, the sensor's threads seem just a bit too wide to thread in.
Any suggestions here are greatly appreciated. Cheers.
a) what thread pitch are the original sensors in an '86?
b) the sensor in the intake manifold, I believe, is for the ECM. The one on the driver's side head is the fan switch, I believe - what does the sensor in the RH head do? The instrument panel?
c) the threads in the Edelbrock heads are 1/2" NPT, I believe. The goal here is to adapt the old sensors to the new heads, but I can't seem to find any adapters that do so; I suspected the sensors were 3/8", but when I try to thread the sensor into a 3/8 to 1/2 adapter, the sensor's threads seem just a bit too wide to thread in.
Any suggestions here are greatly appreciated. Cheers.
A 1/2 NPT to 3/8 NPT "bushing" should be an easy find. If you're cylinder heads wear 1/2 - NPT the OE switch/sender would "drop in". Sounds like you maybe don't understand NPT *OR* maybe the bushing isn't correct that you've bought. Very early SBC heads did use 1/2 - NPT senders. it wouldn't be unusual for the sender/switch threads to be very tight in the new bushing.
Right cylinder head rear would be used for the gauge sender in the cluster.
Take your bushing/adapter to a parts store and check the threads using NPT fittings from their stock.
Last edited by WVZR-1; Jun 27, 2017 at 02:21 AM.
Race Director
Joined: Apr 2002
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From: Anaheim CA
Yes and yes. The passenger side temperature sensor is for the instrument cluster.
Team Owner
Joined: Sep 2003
Posts: 25,386
Likes: 2,737
What I didn't mention in my earlier post is that I believe the sender/switch is done in NPTF and even though the pitch and thread count is the same as NPT the major and minor diameters are different and when I mentioned it wouldn't be unusual to have "very tight" threading I maybe should have explained.
This explains maybe better than I could.
http://www.ring-plug-thread-gages.co...PT-vs-NPTF.htm
When using the appropriate bushings or nipples I've never experienced a fit that I was concerned with. I've used more than a few. The *F* is a FUEL spec for NPT.
This explains maybe better than I could.
http://www.ring-plug-thread-gages.co...PT-vs-NPTF.htm
When using the appropriate bushings or nipples I've never experienced a fit that I was concerned with. I've used more than a few. The *F* is a FUEL spec for NPT.
