Engine Rebuild

[scotty71]

Just would like to know from restorers when they rebuilt their halftrack engine, did you find it necessary to have your crankshaft and flywheel re-balanced? or did you not worry about having this done.

[steve1973]

The flywheel you should not have to redo. If the machine shop does anything to the crank they will check the balance otherwise leave it alone.

Steve A.

[Outsider]

You only have to work on the flywheel if it is rough / wore where the clutch plates ride up against it. Then it would have to be refaced at a machine shop.

Steve

[scotty71]

Went to see the owner of the engine shop after he has had time to go over the engine.......

Block - had been re-bored to .030 oversize, BUT.... has had another .020 worn by the piston rings. Might be able to get away with going .060 over size?

Head - Can be used but the chipped part a worry. He suggested getting chip welded up, but, will get new head from Gary instead.

Cam - No good. Flat spots on the cam lugs. Need to get a new one.

Valves - Need replacing.

Valve guides - Don't need replacing.

Crank - This is a bit of a worry. He was a bit concerned about how much has been worn and how much would be needed to be machined to get correct dimensions.

Bearings - Mains and con rod bearings are completely stuffed. There are chunks of bearing material missing from some of the con rod bearings and bad scoring.

Looks as though the lubricating for the bearings has not been working for some time before I bought the vehicle, as all the bearings are pretty much worn down to the backing metal with no bearing metal left.

Overall the engine has had a hard life before I got it. A lot of work will be needed to get it back to good running condition. Just waiting on final machined dimensions before I start getting the bits that I need. Will take some time to get up and running but will be worth it.....I hope.

[scotty71]

This may be a reason to look at the bearings of your smooth running second hand engine........and these are just the con rod bearings. No wonder my crankshaft is looking a bit sad....

[emptyhead]

That sucks. I picked up my engine from another guy that had plans to restore his track that was in worst shape then mine. The shop did a complete tear down and line bore, sleeve, magnaflux,rings piston, valves and anything else. It hurt up front but will be worth it down the road. Good luck Scotty.

[KC]

While going through the same process on our HT several years ago, Rod shaver had NOS connecting rod sets of 6 for $100. That was cheaper than what the shop wanted to check the original ones. Also, we had trouble finding a good crank shaft. Both of the take out ones we had were worn and several cracks were discovered when Mag fluxed. Gary H had NOS cranks for $500 if I remember correctly. When you figure the money involved checking a crank and turning down the crank for undersized bearings purchasing the NOS crank was easier. Plus you can use STD bearings. I may have a usable takeout cam shaft if you can not find one.
Karl

[scotty71]

Engine update......

Just been advised from the engine shop that it will be possible to machine the bores to .060 over size for the pistons. 

I have decided that although a bit expensive, instead of trying to get the old components machined to tolerances, I will be replacing every internal component that I can get except for the valve lifters as they only need a minor resurfacing to get back to spec. Already aquired new camshaft, crankshaft, valves, pistons, con rods. Still need to get all the bearings required.

Scott.