Sport engine not turning over

[lancianut666]

Hi all
The consortium has received a sport engine with many thanks to Peter Chittenden who dropped it off at Hartlepool during the tour part of the Great Northern Weekend. The problem is it only turns over about half a revolution then jams with a clunk. Peter and I thought it was a valve stuck open and hitting a piston. Another possibility struck me as the valve gear and the top of the head under the rocker covers looks very clean (will have to check the plugs) is that the engine has never ran due to the jamming up. It then crossed my mind had someone put the no3 piston conrod in the wrong way round? it is easily done (hands up who has done it?)
I will try and see if I can check for stuck valves through the plugholes and possibly take the exhaust manifold off before I whip the sump off.
Clarkey

[mikeC]

Back-to-front conrod was my first thought.

[lancianut666]

Hi all
The plugs were sooty but were they from before any work done on the engine? Any way I have checked as best I can peering down plug holes and tapping lightly the tappets and it seems all the valves are free. The gear box was making an awful racket when I turned over the engine (only about half a turn) so I took the gearbox off but the engine is still jamming. On reflection a gamble on a sump gasket to check the conrod will be quicker than taking the head off so I will drain the oil out and get the sump off. Beginners mistake on getting the gear box off was not removing the clutch fork/release retaining bolt. On reflection it is a proper clunk when the engine jams that you can feel so I am leaning towards the conrod theory but I think the engine was said to be running so I will go over all the valves again tomorrow. Hopefully the engine Elves will have sprinkled some magic dust on that sticky valve(s) tonight and we will all live happily ever after.
Clarkey

[lancianut666]

It is conrod for cylinder 4 that is different. Will need to get the sump off to have a look see.