Looking to buy a compression tester. What size is the threads on the plug holes? Testers say they are good for 12mm 14mm 18mm. Not sure what to get.
They are modern plug sizes, T's are 1/2" pipe thread.
They are 1/2 inch pipe thread. You can get a spark plug adapter for 14 mm plugs then use the 14mm tester will work. Vendors sell those adapters, don't know if you can buy just 1. So body explained how they made their own a week or so ago but don't know how to find it
The vendors sell an adapter, 1/2" pipe thread OD and 14mm ID
Looks like Ebay has several starting at about $19 each.
Innovative Products Of America 7885 Spark Plug Hole Adapter 18mm
Sorry gave the wrong part # and don't know how to edit.
Lang's has them for $15 for 4.
Far to much Troy, Langs are $14.95 for a set of 4.
oops! we are both on the same track now!
All the testers I see go to 300 psi! Where can I get one that goes to only 100 psi?
I just made an adapter with a 1/2" npt plug. Should work.
Jonathan, here's a thread discussing how to get a 100 psi tester: http://www.mtfca.com/discus/messages/257047/276119.html?1332284570
But I think you'll get a somewhat useful result with a 300 psi tester too - even your thumb will tell if one of the cylinders has significantly less compression than the others - and if some oil down through the spark plug holes improves compression
(if oil improves compression significantly , then the rings are less than perfect - and if nothing is improved with oil but still low, then it's a valve problem.)
I have an old one with a "universal" rubber tip just shove it in there and have someone turn the engine over a couple of times take the reading then press the release button and move to the next cylinder
Gosh, I bought an adapter from someone online a couple of years ago when I got my compression tester but unfortunately can't remember where. Only paid about $5 for it and I think shipping was even included. Don't know how they do it.
I use my Craftsman screw in 300LB compression checker all the time. Works fine at the low range. I think the reason it works at the low range is because it's the screw in type and holds the seal better then a universal rubber tip type. I have found that it does not matter if the throttle is open or closed I get the same readings, the T has such low compression anyway.
Pull all the plugs, put it in, crank over thru 4 or 5 compression strokes, read, write down the number, repeat.
I bought a 0 to 100 psi gauge at Graingers.
Buy a different gauge and replace the original one Johnathan. I replaced my 300 lb gauge with a 0-80 lb, 6" diameter one that's easy to read.
I have a Matco 300 PSI compression tester that uses ordinary air tool connectors at the spark plug hole. I went to Home Depot and bought a 1/2" NPT - 1/4" NPT bushing reducer to make it fit the Model T sized spark plug hole. The reducer was something like $2.50 including tax.
No reason to search out a lower PSI gage, the 300 PSI gage is plenty accurate.
Like this only brass: