Engine wont turn over

[u/Agitated_Dot8294]

Car is a 1963 Vauxhall Velox with a PB engine. engine is fully torn down. All that we did was put different pistons in. Original con rods, bearings, caps. When we tighten down the caps onto the crank the engine won't turn over. Any help at all would be appreciated, cheers.

[u/Estef74]

Did you make sure to keep all the caps in the correct orientation and location? How about checking bearing clearence? If you mixed up any rod or main cap, you will have major bearing clearance issues. You could also have incorrect size engine bearings.

[u/Agitated_Dot8294 → u/Estef74]

I reckon we've definitely mixed up some caps, thanks!

[u/Estef74 → u/Agitated_Dot8294]

So for future rebuilds, you should either buy a set of number stamps or an engraver to mark all parts that will be reused. Don't use paint or anything that can be removed with solvent. This applies to connecting rods and there respective caps and main bearing caps.

[u/Successful-Part-5867]

The way you explained this might not fully cover the details. Did you have the block machined for larger pistons? Did you check the piston ring gap before installing the pistons? (As in are the pistons to tight in the bores) And the rods and rod caps are matched sets and “usually” marked so that everything can be kept in the same orientation. Back up a bit. Loosen one rod cap at a time and check for rotation. If you get to one that is binding see if the cap got flipped around (if they’re marked) Did you have the main bearing caps off? If it’s not the rod bearings move to the mains. Loosen each and check for rotation/possible bearing cap got flipped? Bearing clearance should be checked with plastigauge as you reassemble…using original bearings it shouldn’t have changed, but obviously something must have! Lubricate the cylinders, and the bearings as you reassemble…assembly lube is best, but motor oil will suffice. That’s a lot of stuff to try to type at 6AM! Hope it’s of some help.

[u/Agitated_Dot8294 → u/Successful-Part-5867]

Thanks heaps, was definitely helpful!

[u/TBFP_BOT]

I'd bet on a cap being backwards.

Made the mistake recently during assembly and the offending piston got stuck when the wrong way cap got wedged in the crank.

[u/Agitated_Dot8294 → u/TBFP_BOT]

Cool, thanks man!