How much compression is enough?
Can't get the Jeep started. 1968 CJ-5 with the 225 C.I. V6. The last time it was running it developed some serious backfire, mostly out the tailpipe. I was close to home so I just limped in. I've been through LEVE's list. Fuel OK, even has a new Holley 4160. Spark is good and new wires and plugs. Timing is dead on. I've checked it all.
The one area of concern is compression. The jugs are getting up to 140 and within about 10% of that, except #1 & #3 which only getting 55 PSI. OK, so I need a head gasket. But, my question is would low compression on two cylinders be enough to keep it from starting?
It just seem like it should still fire.