Piston ring expanders are cheap and make removing and replacing piston rings a stress free activity and I've been using some like these for more than 20 years – bought after I broke a ring using my fingers. https://www.machinemart.co.uk/p/cht260-piston-ring-pliers/ You'll be fine, these engines are as simple as they get, no water pump of course and not even a timing chain. Clean, measure and check everything before you start the assembly and the cleaner the work space is the better chance you have of doing a good job. And don't rush things, slow and steady wins the race. Another vote for checking the bottom end, it's only a few more nuts and bolts.
What do you suggest checking and what's involved. I'm reluctant (very reluctant) to split the case. I've also got to replace the large crank oil seal - tips and hints on how best to do it ?
Big end bearings can be replaced and the cam can be inspected with the case assembled but the main bearings can't be checked without splitting the case, and they'll have a bit more load when you do a top end overhaul. If you are replacing the flywheel seal you should also replace the fan hub seal at the other end. Both seals are easier to remove if you split the case, but you can use a self taper screw into the seal and pull it out – be careful not to damage the case bore.
You’ll be fine. When you work on the crank regarding your con rods, hand tighten the crank into the flywheel and do it upright. It’s only 8 nuts to release the con rods.
OK. Please provide idiot proof instructions on what I should be doing to the bottom end to check things out.
I'll leave that to others, but a positive point worth noting is that 99.9% of the horror stories of finding everything fit for the scrap heap are type-1 engines, not type-4. I don't think I've heard of a type-4 needing a line bore though I suppose it happens. When I bought my base gamble 2L engine from ebay we could have reused the bearings even. Every part of it was fine, so I expect you're not going to find horrors, but end up with new bearings because why not and maybe new cam and followers. I would be reusing those most likely, but I knew a chap who could reface the followers correctly. Mr Westy views this differently and he's not wrong... but neither am I.
Bedtime reading https://www.thelatebay.com/index.php?threads/morks-type-4-1800-ap-engine-project.30925/
Beware the oil strainer nut on a Type 4. It's a really and I mean really, poor design and can cause catastrophic damage to the crankcase if overtightened. To split the crankcase undo the strainer nut first and then the bolt in the casing that the strainer hangs off – it's buried in the casing between the push rod tubes. Remove the oil pump nuts but don't remove the pump until the casing has just started to loosen. All the other bolts are straightforward but some take some finding. Don't use a lever to pry the case halves apart, if it's stuck search for another bolt. And as you lift the half casing off be careful not to let the conrods drop onto the cam. Once you have the casing apart you can inspect the cam for damage. If the miles on the engine are around 80k the chances are it's worn. Keep the cam followers in order so you can fit them back in the same position. If it's an original cam the gear will be riveted on, aftermarket cam will be bolt on. I prefer to work on the crankshaft when it is horizontal, |I don't see an advantage in having it vertical. Conrod removal is straightforward but keep the caps with the same rods – they should already be match marked. To remove all of the main bearings the gears will have to be pulled off the crankshaft. I made a puller from angle iron and studding, a bought puller will do although the legs might need to be ground to be thin enough to fit behind the gears – it's obvious when you have the bits in front of you. Then it's measuring and inspecting for damage or wear. I would replace all of the bearings as a matter of course; cam, mains and big ends. Post pics when you have it apart.
I have a deadline and despite my reluctance I find I'm still a maniac once I have a grinder in my hand.
Why? You must have some tools and ability because you've already taken the engine out and taken the heads, B&Ps and flywheel off. The rest of the engine is simple once you get into it and it's easier to do than write about it. Nevertheless, the Type 4 is a tough engine, not like a Type 1, and the chances are you can do a top end rebuild with a modest capacity increase without any problems, but at least inspect the cam through follower bores and check or replace the big end bearings. And if you're brave you could also do the piston oil spray mod to the con rods. You can do it with a square file, it doesn't have to be machined. Post #245 https://www.thelatebay.com/index.php?threads/morks-type-4-1800-ap-engine-project.30925/page-13
