Thread Size Help
Thread Starter
Race Director
Joined: Feb 1999
Posts: 19,659
Likes: 34
From: Lenoir City Tennessee
Ci 6, 8 & 10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15
Thread Size Help
I am working on installing an LS6 in my 70. So far things are going pretty good and I should have a pretty nice little hot rod when all is said and done. I have another quick question and I cannot come up with a definitive answer.
There is a hole in the head that is just behind the last manifold bolt. It is not the one farthest left in this picture but the 2nd one from the left. This hole is plugged by a socket head bolt. What is the thread pitch on this hole?
Any help is greatly appreciated.
There is a hole in the head that is just behind the last manifold bolt. It is not the one farthest left in this picture but the 2nd one from the left. This hole is plugged by a socket head bolt. What is the thread pitch on this hole?
Any help is greatly appreciated.
Thread Starter
Race Director
Joined: Feb 1999
Posts: 19,659
Likes: 34
From: Lenoir City Tennessee
Ci 6, 8 & 10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15
I have it plugged right now but I am wanting to put a sending unit so I can use the stock gauges in my 70 vette. If I can cut my sending unit down to that size, I am golden and will have a functioning temp gauge.
Thread Starter
Race Director
Joined: Feb 1999
Posts: 19,659
Likes: 34
From: Lenoir City Tennessee
Ci 6, 8 & 10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15
One place I read that that thread size is 12X1.5 and another says it is 14X1.5. I just need confirmation that it is either one or the other.
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
I have the plug part number at home and can look up the thread. I can't see the picture at work, but if it is the one ?I think you are describing the thread is the same as the coolant temperature sensor.
Thread Starter
Race Director
Joined: Feb 1999
Posts: 19,659
Likes: 34
From: Lenoir City Tennessee
Ci 6, 8 & 10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15
It is the same as the coolant temp sensor. On the drivers side, the coolant temp sensor is in the head. On the passengers side rear, it is plugged. I was going to try and cut a stock 1970 temp sensor to match this thread and use it in the hole. That is, if there is enough material to make it work. I am going to stop by Ace Hardware this evening on the way home and pick up a couple of bolts and see which one fits. I will post back with what I find.
Race Director
Joined: Jan 2006
Posts: 10,554
Likes: 33
From: Not on either liberal coast.
...ahhh...bolts and pipe plugs are usually different thread/pitch. You sure don't want to mess up the aluminum heads!
Why don't you just remove it and take it to your favorite automotive/hardware store and find a reducer (OD to fit the head and ID to fit the oem sensor). You might not even have to cut down your oem sensor.
Why don't you just remove it and take it to your favorite automotive/hardware store and find a reducer (OD to fit the head and ID to fit the oem sensor). You might not even have to cut down your oem sensor.
Thread Starter
Race Director
Joined: Feb 1999
Posts: 19,659
Likes: 34
From: Lenoir City Tennessee
Ci 6, 8 & 10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15
The thread size in the head is 12X1.5. I picked up two bolts at Ace hardware today. 12X1.5 and 12X1.2???, those suckers are $2.76 each!!! They are not even the high grade stuff either. Needless to say, they will be going back to Ace tomorrow with the receipt. DAYUM!!!!
I am going to try a little home grown engineering and see if I can get the stock sensor turned down and put some threads on it to match. I have a few machinist buddies that might have a little free time on their hands tomorrow. Maybe I can take advantage of some of that free time.
I am going to try a little home grown engineering and see if I can get the stock sensor turned down and put some threads on it to match. I have a few machinist buddies that might have a little free time on their hands tomorrow. Maybe I can take advantage of some of that free time.
Last edited by Eddie 70; Jul 8, 2008 at 09:50 PM.
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Burning Brakes
Joined: Jul 2000
Posts: 1,134
Likes: 1
From: Arlington Texas
Here are the dimensions on the coolant plug.
I don't know what the thread size of your sending unit is, but Autometer makes an adapter: http://www.autometer.com/cat_accesso...il.aspx?vid=61
I don't know what the thread size of your sending unit is, but Autometer makes an adapter: http://www.autometer.com/cat_accesso...il.aspx?vid=61
Thread Starter
Race Director
Joined: Feb 1999
Posts: 19,659
Likes: 34
From: Lenoir City Tennessee
Ci 6, 8 & 10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15
I had it milled to make it 12mm and it works like a champ. I put teflon tape on the thread and an aluminum crush washer for a motorcycle drain plug. It should not leak and make good contact with the head for a good ground.
Here is my solution.
Here is my solution.
Race Director
Joined: Jan 2006
Posts: 10,554
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From: Not on either liberal coast.
That's a nice solution to your problem. I always ended up using reducers which didn't always look good.
If you start experiencing fluctuations in your coolant readings, it might be the TEFLON tape. Brass pipe thread fittings usually don't need sealant as they're tapered. I liked using a sealant as well and found TEFLON tape didn't always bring consistent readings due to poor grounding of the electric senders. Once I switched to TEFLON based paste, they were fine.
If you start experiencing fluctuations in your coolant readings, it might be the TEFLON tape. Brass pipe thread fittings usually don't need sealant as they're tapered. I liked using a sealant as well and found TEFLON tape didn't always bring consistent readings due to poor grounding of the electric senders. Once I switched to TEFLON based paste, they were fine.