I'm looking to do a compression test and a leak down test on my 90 mustang. The problem is that I have gt40 heads and the the testers do no screw in. Is there a certain adapter that I need or am I doing something wrong?

 

YOU NEED ONE FOR 5/8 plugs

 

Do you have a link to where I can get one. I haven't been able to find anything and it did work with trick flow heads.

 

any compression tester kit should have a bunch of adapters to it. you might be missing some, so i'd suggest contacting the company of the product you own.

 

I got it from summit I will give them a call. Thanks for the help.

 

I may be reading too deep into your post but why would you need to do both?

If you have access to a leak down test. That should tell you whatever you need to know.

 

With a compression test you can find out which cylinders are low on compression with a leak down test you can use the information from compression test to look deeper into the bastard cylinders and determine if you have a valve blowing by or a worn rings.

 

Yes compression testers should have about 2-3 different thread adapters the tfs heads like most aluminum heads have a 14mm thread and the cast heads have the 5/8 thread!

thats why it worked with your trickflow heads and not your cast heads!

 

you start with compression test, if you get a lower than normal reading, than you move to a leak down test to narrow it to a valve issue or ring issue.

 

I was able to pick up an adapter at the auto parts store and I was going to do both just out of curiosity. Thanks for the help again.