304 Low compression in cylinders 1 & 3

So in early January I picked up a 76 CJ5 with a crate 304 that has about 39K miles on it. I drove it home over 40 miles with absolutely no issues.

About three weeks later I drove it after not driving it since I got it home about 3 miles. It was a little hesitant, some sputtering, etc. About two weeks later my ignition module went so I replaced it with an HEI with no issues.

I went to drive it to test it out after the ignition upgrade and it continued to sputter so I did a compression test. I have low compression in cylinders 1 & 3. All the other cylinders are at 150lbs, except those two which are at about 65lbs.

I do find it odd that I would lose two cylinders without any real driving in the interim (only three miles), although the numbers don't lie. It just seems really strange to me.

 

Since the low readings are in 2 cyls right next to each other, I'd suspect a bad head gasket.

 

Try a leak-down test. http://www.carcraft.com/techarticles/116_0406_cylinder_leakdown_tester/viewall.html

There are lots of articles on the net about how to do a leak down test, and how to build a leak down tester.

Or just pull the head and look.