What qualifies as good compression numbers on a 13BT?
 

I've got a 10th AE that's slow as molasses. I've been trying to figure out why. One of the steps I took was to check the compression on the engine. I removed the fuel injector fuse, removed both top plugs, screwed in a Craftsman piston engine compression gauge, held in the release valve, and cranked the car. It registered several even pulses at about 50-55 on both front and rear rotors. A friend of mine told me that this is "low compression". The shop manual says that normal compression at 3000 feet above sea level is 57PSI. I'm at between 6000 and 7000 feet above sea level.

https://img267.imageshack.us/img267/...mpensation.png

Is this normal compression, or is it time for a rebuild?

The manual states the facts, I have never seen this but I doubt they would stick it in the manual just for laughs and giggles... It's should be normal using the altitude compensation.... At 3k feet, the manual states under 57psi more around the area of low 50 upper 40psi (3.8-3.9 kg/cm^2) if you look at the graph carefully...

Edit: did the conversion, you are looking at around 54psi at 3,000 ft...