My friends 1979 Rx7 has been sitting for around 5 years. After doing the ATF trick and other stuff, we got the car running. He has been starting it once a month for about 6 months. The car seems to idle really good around 1100rpm. Unfortunately when we drive it, it only goes upto 35mph in second gear, and won't go any faster.

This weekend we took a normal compression tester and did a quick test. With the valve held in the rear rotor hit 3 even pulses at 40 psi, and the front rotor had 3 pulses around 50 psi. Then we tested the max compression by not holding the valve in. The rear rotor would only generate 65 psi, and the front rotor built up to 80 psi.

From looking at these numbers it seems the front rotor is questionable, and the rear rotor is shot. I was just thinking that it was strange that the car would idle so smoothly.

Does anybody think that the engine may not be bad, and we could do some tricks to restore some compression? Just looking for ideas.

Thanks.

 

Pour a tablespoon of oil down each primary carb barrel and see if the compression comes up. That'll tell you if its just shot seals, which it probably is since the pulses are even. No magic bullet to restore compression that I know of.

IF, and thats only IF you still have stuck seals, another MMO/AFT treatment may help. Try it, cant hurt.

 

Stuck seals? It might be a dumb question, but I searched and can't find exactly what is meant by "stuck seals."

 

Carbon build up in the seal grooves (apex, corner and side seals) causes them to bind up in their grooves and then they cant press against their respective sealing surfaces and you lose compression.

 

Check out hose de-carbon threads in the FAQ, I used powerfoam last night, and it did wonders

 

thanks, Carl.

 

I will definetly have to give those ideas a shot.