gmgbv6 wrote:<br />I recently purchased a basket case '67 305 scrambler with rebuilt engine. The pistons and rings are new. I don't know if the cylinders were bored and if oversized pistons were installed. This being said, the problem i'm experiencing is low compression. Bill Silvers text says that I should be looking for 150-175 psi Both cylinders read @ 100 psi until I add a spoonful of 30 wt. oil. Then the pressure climbs to 150 psi. The motor loses power at higher rpm's and misfires. I've assumed that the low compression is the probable cause Would low readings such as these be typical of a newly rebuilt motor before the rings become seated? The motor has about 50 miles on it since rebuild and I was thinking that the rings should have seated by now.<br /><br />Any thoughts that you might have on the matter would be greatly<br /><br />appreciated.<br /><br />Thanks,<br />Gary Lee<br />
<br /><br />If the cylinders were honed, I expect the rings are broken or installed up-side-down. You can read indented writing like "0.25", on the "top" of each ring. I'd pull it apart and also put a new cam chain in it to help it keep running at its best.
