In-Frame Engine rebuild

Tue Oct 08, 2013 9:15 pm

I have a early '48 Cub with low compression and is very difficult to start & keep running. I have seen some in-frame rebuild kits and wanted to know if anyone has some experience or advice with an in-frame rebuild kit. My thoughts are to do a valve job and an in-frame kit that will include new rings & pistons that will increase my compression.
I'm not really interested in doing an overhaul and complete restoration just yet. I would like to get it running and enjoy it for a while before going that far.

Any thoughts or suggestions before going down this path would be greatly appreciated.

Re: In-Frame Engine rebuild

Tue Oct 08, 2013 9:21 pm

I would pull the engine and put on a stand or the bench. Much easier to access the engine for measurements.

Re: In-Frame Engine rebuild

Wed Oct 09, 2013 10:52 am

I agree with Eugene but I also understand not wanting to tear the tractor apart. I've done what you are suggesting and it's very do-able. Two other drawbacks are you can't change the front or rear main seals. The front seal requires taking off the front end of the tractor (and a special puller for the front pulley) and the rear seal, a split at the bell housing. Mic'ing and plasti-gauging require crawling around under the tractor and FWIW the rear bolts on the oil pan are no picnic to re-install. If you find the cylinder bores are too far out of spec you'll need to take the engine out anyway, I got lucky. I replaced the front seal on mine as it was leaking pretty badly but not the rear, it wasn't leaking (and still isn't :{_}: ). On the plus side ol' Smokey is running real well now, maybe a bit stronger than before, good oil pressure, and no more blue smoke!

Re: In-Frame Engine rebuild

Wed Oct 09, 2013 11:47 am

Unless you have the tools and knowledge to mic it out, I agree with Eugene that you are better off pulling the block, and would add that you should take it to a machine shop to have it measured and see where you are. Not much sense in replacing pistons and rings unless you know whether or not you need to go oversize.

When I did the engine on my 59, everything was within specs. If I had just bought a kit, the pistons would have been wasted money.

Re: In-Frame Engine rebuild

Wed Oct 09, 2013 11:56 am

pferguson1962 wrote:I have seen some in-frame rebuild kits.
Engine block is not sleeved. Do not purchase a kit until the engine has been measured to determine needed machine work and parts.

Re: In-Frame Engine rebuild

Wed Oct 09, 2013 11:58 am

The most important thing I learned on this forum since I started the restoration of Rex '48 is to follow the recommendations from the members of this forum. Each and every time I've departed from this - I'd wished I had not. Having done in-frame rebuilds with my father and brother as a youth it's just much easier to have it on a stand as recommended herein. Also, by sending it out it will be boiled out and clean inside and out for better performance and painting.

Ken

Re: In-Frame Engine rebuild

Sun Oct 13, 2013 11:05 pm

Definitely recommend pulling it even though I agree its a lot more work.
I was a diesel and heavy equipment mechanic for 15 years and the partial rebuilds didnt work out well too many times.
While occasionaly you can get away with a ring job to "get by" usually by the time the rings have worn down you will have critical dimensions wrong such as cylinder taper,out of round, scoring and a top cylinder ridge that can break your new rings/piston if not removed.
Also without a proper cylinder crosshatch your new rings may not seat in causing a lot of the problems you now have.
Add to this not being able to clean/hot tank the block well and not being able to repalace oil seals that may fail soon.
If done right the first time you will have a solid base to build and restore the rest of the Cub.
Good luck and enjoy the time spent on this fun hobby :)

Re: In-Frame Engine rebuild

Mon Oct 14, 2013 6:01 am

Fireman Bob wrote:Definitely recommend pulling it even though I agree its a lot more work.
I was a diesel and heavy equipment mechanic for 15 years and the partial rebuilds didnt work out well too many times.
While occasionaly you can get away with a ring job to "get by" usually by the time the rings have worn down you will have critical dimensions wrong such as cylinder taper,out of round, scoring and a top cylinder ridge that can break your new rings/piston if not removed.
Also without a proper cylinder crosshatch your new rings may not seat in causing a lot of the problems you now have.
Add to this not being able to clean/hot tank the block well and not being able to repalace oil seals that may fail soon.
If done right the first time you will have a solid base to build and restore the rest of the Cub.
Good luck and enjoy the time spent on this fun hobby :)


:Dito:

I could not agree more!!!