Working on 78 4.2l straight 6 cj7 at the moment, or i think it is a 4.2l?how do you tell the differance between 4.2l and 3.8l? can anyone advise me what the height of the pistons at tdc from the top of the block should normally be? as i have the head removed and they seem to not come up enough? Its only running at 90psi and i think this may be a little low? Also there is no back pressure surgesing its not breathing into sump? Engine has had overhaul in its life so not sure if it has been built up with the wrong pistons/rods? Any help/surgestions would be gratefully received..
