Skidoodle
Member
This is the situation: Recently, I acquired a non running, 94 GTX with the 657 engine that, according to the PO, had just had the top end rebuilt and he had not been able to get it running afterwards. I can tell that it has new cyl base gaskets and the old pistons were laying in the storage bin, one of which had a hole in the top and heavy scoring all around the sides. The first thing I did was to check the compression which revealed, PTO=60psi and MAG=120psi. Not a good sign at all! I tinker with it some and decide to pull the intake and have a look at the timing which was WAAAAY off. So I Check and mark the locations using a degree wheel and set the (147)rotary valve at 130 degrees with the MAG piston at TDC. However, I was not completely satisfied with the final installation, even though I flipped the valve to see if it improved, it just did not line up perfect. While I had the intake off, I went ahead and disassembled the carbs and cleaned them and put new fuel lines on, etc.
Now I can get the engine started and it runs fairly good but not right, so I rechecked the compression and it still shows the same readings as before. Could the rotary valve being slightly off cause a low compression reading? Or, as I suspect, this egg-head that I bought it from do something stupid like put a used piston in it?
Now I can get the engine started and it runs fairly good but not right, so I rechecked the compression and it still shows the same readings as before. Could the rotary valve being slightly off cause a low compression reading? Or, as I suspect, this egg-head that I bought it from do something stupid like put a used piston in it?
