Tecumseh 10 HP

This message is a reply to an archived post by joe csuti on December 09, 2011 at 13:17:37.
The original subject was "Re: Tecumseh 10 HP".

Will the hh120 piston work in my 1967 john deere 112 with a hh100

The hh120 piston will work in most of the hh100 eng,however block will have to be bored as hh100 bore is 3 5/16" and the hh120 is 3 1/2",two of the eng I had rebored were old jd 110/112 hh100 eng(drain plug on bottom of block).

Ok i think i will give this a try both of hh100 bores are worned to the point i can see the piston ring.

I will use the hh100 crankshaft and connecting rod right.

First thing to do is get a service/repair manual for the hh series eng(paper/cd)as you will need same to get spec for crank rod journal diam,piston bore diam,valve guide diam & torque spec for all bolts on eng.
Disassemble eng and take block & crank to a shop that does small eng boreing,have them measure crank rod journal for wear to see if you can use std rod or if crank will have to be ground for an os rod or possibly crank will have be replaced if journal too worn,have valve guides measured to see how much they are worn & if they need a boreing for os valves,have cyl bore measured to see if you can get away with a hh100 020" os piston set if not then figure for having block bored for a std hh120 piston,the hh100 .030/.040 os piston sets listed in parts drawing for eng havn't been avail for close to 20 yrs.From service/repair manual write down spec's for crank rod journal diam,valve guide bore size & piston bore diam and take with you when taking block/crank to machine shop to see what parts you will need to buy.

The internal parts should be the same for hh100/120 eng,to check look up your mod/spec# at link below then check part# for parts needed & also look at several hh120 eng listings,the part# should be the same.
tecumseh

Ok thank you i see most things are the same i see the cranshafts have differnt part numbers. I do have some specs on the hh100

Some tractor mfg speced the shaft 1 1/8" when ordered from tecumseh in addition to a specific length depending on application,the normal shaft size for a replacement hh100 eng was 1" this can account for the different pn crankshaft's,this is also why it's also important to lookup mod/spec# of your eng to get correct pn for crankshaft or other parts that are needed.

I think the hh100 crankshaft and hh120 crankshaft are differnt because the hh120 has a longer storke.

My plan is to use hh100 crankshaft rod and hh120 piston after i get bored out.