My 1963 SIIA’s engine has a rattle when under load, so I carried out a compression test. After finding an ‘8’ stamped on the head (at bolt two of the torquing sequence) I presumed it’s 8:1 (the engine number on the logbook is 279562).
The test was disappointing – 125/130 dry – and only pistons 1 and 4 improved when oil was dropped in. With the cylinders out, I found every top ring in bits! The second groove had two rings in – is this normal? Before removing the conrod from the crank, I also noticed a load of slop, allowing fore-and-aft movement of the conrod.
Also, none of the pistons has size markings. They have numbers ‘1’ to ‘4’, but this is as piston one to four. Piston one has a ‘D’ stamped on it, piston two has ‘A’ and three and four have ‘C’ on them. I’m assuming it’s the original engine (there’s 50,000 miles on the clock).
I am also confused about the oil journals at big end to crank – should the holes on the shells be on the opposite side to the oilway on the conrod?
I have gone for standard pistons to get me back on the road while I rebuild another engine that was given to me.
Steve Male, Paulsgrove, Hants
You’re optimistic in thinking this is an original 50,000-mile engine. Your engine number doesn’t correspond to a Land Rover one, so I can say that this motor has had at least one rebuild, possibly a very long time ago.
The fact that the pistons are marked ‘1’ to ‘4’ means someone has had them out and marked them to go back in the correct position.
The ‘8’ on the head in the centre does suggest it’s an 8:1 compression ratio. The lower piston rings are of a split design, so are probably okay. You shouldn’t be able to fit the main bearings the wrong way round: there’s an indent in the block and corresponding extrusion on the shells to ensure they can’t spin if fitted properly.
As for fitting new standardsize pistons, for the time being you really need to measure the old ones to find out if they’re oversize or not, but the letter markings suggest they’re standard.
From what you say, I’d say you’ve made the right choice in rebuilding another one; it’s a credit to these engines that they still run with so much wear in them!
This workshop advice appeared in the January 2016 issue of LRO. Back issues are available to download on digital devices here.