[AT] Drawn out 1949 AC-B engine rebuild

jtchall at nc.rr.com jtchall at nc.rr.com
Sun Mar 8 18:23:19 PDT 2015


There are a ton of variables to consider here. If money is no object, send 
the entire engine to a machine shop and tell them to do it right, you'll 
have nothing to worry about.

Now lets get back to reality. If its just a plain old tractor that you 
aren't planning on doing a top notch restoration job on, then you can 
probably cut some corners. If the engine wasn't knocking, new inserts or 
removing a few shims will probably be sufficient for the crank. Pistons that 
wiggle are very bad. Measure the bore, you'll probably find the engine needs 
boring or a new set of sleeves. I highly doubt a set of rings will do much 
good. Send the head to be faced and valves ground, if you pull the manifold, 
send it to be faced as well. Tell the machine shop exactly how much you are 
going to drive this tractor and use some common sense regarding valves, 
seats and springs. If the tractor is only going to be run an hour or 2 a 
year, I might get real cheap on the head work if it was only slightly out of 
tolerance. But if I had to go to the expense of new piston and sleeves, I'd 
have the head done right. Bottom line for me is to measure up all the wear, 
you'll either just squeak by spending a little or have to go all in for a 
total rebuild. If you can, get somebody to measure the bore and crank and 
that will really help guiding you into making a decision what to do.

FWIW, we pulled one of our working tractors in the shop and did a cheap 
rebuild--crank and bore were way out of spec. We knew better and did it 
anyway. About a year later we yanked the whole engine out and sent it to the 
machine shop with instructions to make it all new. We just put a head gasket 
on this past week, logged about 1500 hrs since the proper rebuild. I had the 
head fully serviced as well as the manifold faced. No need to make the same 
mistake twice!

Keep us posted!

John Hall





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