Size info for plug for cylinder head
Thread Starter
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
Size info for plug for cylinder head
As you all know, both cylinder heads are drilled and tapped to accept the temp sender for the analog coolant temp gage. Of course only one cylinder head gets the sender while the other is simply plugged. I need to buy a plug, does anyone know the size? I don't have a tap that big in order to measure it and I really don't want to lug a cylinder head into the hardware store 
Team Owner
Joined: Sep 2003
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Safety Car
Joined: Nov 2008
Posts: 4,328
Likes: 15
From: Jacksonville FL
5/16 or 3/8 are usually the most common plug sizes. Why dont you take the sender to the hardware and match it up if its the same size hole in both? Its alot lighter than the head, lol. Another thought is that pipe plugs in this range are less than a buck, go get a couple different. You may wanna go to an automotive supply with the sender as sometimes the thread pitch can be different. The plug will start and tighten, most likely it will work but if you decide to do something different later on, the threads may be buggered up. Hey I am a plumber, what can you say, get the right thread pitch!
Team Owner
Joined: Sep 2003
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I supplied the link to easily determine "NPT threads since NPT confuses some.
Thread Starter
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
5/16 or 3/8 are usually the most common plug sizes. Why dont you take the sender to the hardware and match it up if its the same size hole in both? Its alot lighter than the head, lol. Another thought is that pipe plugs in this range are less than a buck, go get a couple different. You may wanna go to an automotive supply with the sender as sometimes the thread pitch can be different. The plug will start and tighten, most likely it will work but if you decide to do something different later on, the threads may be buggered up. Hey I am a plumber, what can you say, get the right thread pitch!
Team Owner
Joined: Sep 2003
Posts: 25,406
Likes: 2,744
You can buy 3/8 - 18 NPT and be "confident" of the fit.
I only sent you to the "chart" because I assumed that you likely had the cylinder heads and it's a simple measurement to convert to the correct NPT. Why NOT just have the "shop" that's got the cylinder heads install the plug while the pair is there!
I only sent you to the "chart" because I assumed that you likely had the cylinder heads and it's a simple measurement to convert to the correct NPT. Why NOT just have the "shop" that's got the cylinder heads install the plug while the pair is there!
Melting Slicks
Joined: May 2007
Posts: 2,171
Likes: 1
From: Warwick RI
You can buy 3/8 - 18 NPT and be "confident" of the fit.
I only sent you to the "chart" because I assumed that you likely had the cylinder heads and it's a simple measurement to convert to the correct NPT. Why NOT just have the "shop" that's got the cylinder heads install the plug while the pair is there!
I only sent you to the "chart" because I assumed that you likely had the cylinder heads and it's a simple measurement to convert to the correct NPT. Why NOT just have the "shop" that's got the cylinder heads install the plug while the pair is there!
It is a good bet that they will have them lying around
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