AC B re-ring or full rebuild?

ACReddfalcon · Feb 8, 2016

Hey folks, looking for some advice from guys that know. Im new to the whole tractor thing, picked up a "hand crank only" AC model B. guy told me it should have ran, upon inspection motor was seized, couldn't break it lose via drag and drop clutch. I ended up having to tear it completely down to pound the pistons out, I now have it gutted and am in the process of running parts through the parts washer. Bottom end was all original and everything seems to be good. a bit of wear on 2 of the piston sides and the sleaves are nice minus the top of one has some corrosion/rust. My question is, should I bite the bullet and do a full rebuild on this bad boy or should I just throw some new rings in it and reassemble? Because its a hand crank, what are some things I want to be sure are in good working order to ensure easy starts? Thanks in advance for any replies!

DeltaRed · Feb 8, 2016

Major OH. New Pistons and sleeves

Janicholson · Feb 8, 2016

A nice little handy tractor like that deserves a fresh rebuild. Look to this site for parts and manuals. Jim

rrlund · Feb 8, 2016

What are you going to do with it? Hard to justify a major overhaul on a trailer queen. Is there any ridge at the top of the cylinder walls? Are the ring groves worn at all? Have you checked bearing clearance with plastigauge? There's a fair chance you can get away with rings and bearings and don't need to replace pistons and sleeves.
How do you know the bottom end was all original? Without you knowing the history,you might be replacing a lot of parts that don't have all that much use on them.

JimIA · Feb 8, 2016

On two different occasions I have been involved with hand starts Bs that needed some engine work. Both cases got ring jobs and valve jobs. In both cases the tractors had to be torn down and had new pistons and sleeves installed to guarantee reliability and starting.

CenTex Farmall · Feb 8, 2016

If it was at the point where you had to pound on anything then I believe you are in the market for a complete rebuild. Does it have aluminum pistons? What if you cracked a piston but it's not obvious?

Another common problem with an engine that's corroded together is that the ring lands will be damaged. Yeah, a new ring will fit in there but won't seal properly due to damaged ring land.

Sounds like water got in, possibly through exhaust. Check the valves carefully for pitting. Cracks can start at corrosion pits and you don't want a valve head popping off no matter which way you go with the rebuild!

fixerupper · Feb 8, 2016

New pistons and sleeves can't be that expensive for a B, though I haven't looked at prices. You will have the price of the rings anyway. With new P&S in it you will have the peace of mind you won't have to do it again.

Bob Bancroft · Feb 8, 2016

When I overhauled my C I re-used the pistons and sleeves. But it was running when I took it apart. And it needed bottom end work more than anything. I agree that with yours set up, and pounded apart, you want to be very careful about re-using parts.

As far as starting- you should have valves and manifold in good order when done. The carb. should be right- (not tending to flood) etc. You want to make sure the throttle shaft is tight and sealed in the carb. body, and the choke relief spring/plate is all there. But the main thing- is to make sure the magneto is in good working order, with the impulse working correctly, and timing set correctly. I don't know if anyone around here ever got a broken arm with a B, but I know where there's a WC that broke an arm.

davpal · Feb 8, 2016

I helped my cousin do a C about 20 years ago. It got all painted up as a hobby tractor to take to shows and pulls. He bought it with a lack of oil pressure issue. We tore it down and fixed the pump. It was tired and he could have dumped much $$$ into a full rebuild. I suggested new rings and take the head in for valve job and valve seals. I knew this tractor was never going to "farm" ever again in it's lifetime. Well it turned out fine and the tractor ran great and he even won a few trophys at some tractor pulls. I still see it over to Oakley once in a while as it's new owner still uses it for shows and I think he still pulls it last I heard.

Steve@Advance · Feb 8, 2016

Well, you've heard both sides... But without doing some measuring and honing, it's impossible to know exactly what to do.

To have a good hand start, you'll need good compression. Ring land condition is important, as is a good finish on the bore, especially at the top. If the rust will hone out without leaving major pits, you;ll be ok. If the ring lands are in tolerance, ok. But if either is a problem, then time for pistons and sleeves.

Also the valves will need to be looked at, maybe only lapped if they're just rusty, but again, good compression makes for good starts.

As for the bottom end, if everything is close to tolerance, should be good. It's not going to be doing any real work, so you can get by with a little more wear on bottom. But, sloppy mains tend to leak around the seals...

Dick L · Feb 8, 2016

Only measuring the ID of the sleeves top to bottom every couple inches and at least every third of the way around looking for hollow areas not seen with your eyes. Then run the pistons up and down without rings with a feeler gage to see how much clearance. If you do not have washed out sleeves and you can't run the piston up and down with .010 feeler you would be good to go with new rings. Without measuring it would be a crap shoot to rebuild with rings only. You can see scoring and call it wear but wear without scoring you can not see.

hd6gtom · Feb 8, 2016

rebuild it, you got it apart, fix it right. Hope you did not bend any rods pulling it around and dumping the clutch.

JMS/.MN · Feb 8, 2016

Since it"s so torn down, why not consider switching torque tubes and add a starter? 1940 and newer B would have that, and if you can find a donor, the brakes could be converted to foot type as well. My son is doing that to his and I found everything he needed for less then $200.

2underage · Feb 8, 2016

Unless the AC B tractor was your great grandfathers tractor or something similar it is not worth fixing. These tractors do not bring much over $500 at action and I am referring to ones that are in good condition.

Mark - IN. · Feb 8, 2016

You can get them right here. I've got to do the same with my B. Has to get done.

Mark
YT Overhaul Kits Allis B

ACReddfalcon · Feb 9, 2016

Thanks so much for all the replies and information folks! Based on your experiences and suggestion i'll probably go with the full rebuild. Kits aren't too expensive. To answer a common question, I'll be using it for some field mowing, maybe a scraper blade, got a decent woods deck under it. just going to rattle can it with some AC orange and call it a day.

Thanks again for all the awesome replies!!! you guys rock!

AC B re-ring or full rebuild?

ACReddfalcon

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