8N engine overhaul question

[n8terry]

I am doing this for a friend that has some questions about his 8N with a serial number from year 1947.

His engine has a sleeve diameter of 3.1950
taper less than .003
roundness less than .003
he happens to have a new set of pistons that he has had for several years.

Question: Its going to be more than a show tractor than a working tractor. Do you guys think he can get by ok by putting in new rings?

Is there such a thing as over size rings, and would they work?

how do you know if the valve guides need to be replaced?

The last question is how do you remove the sleeves, his manual says use a crushing tool. neither of us have a clue what a crushing tool is. Hopefully he won't have to remove the sleeves if you guys don't think its necessary.

thanks

 

[TheOldHokie]

Standard bore is 3.1875-3.1885. You measure 3.1950 so he's worn .0065-.0075. Spec'd piston clearance new is 5-10# pull on a 1/2" x .003 feeler so you are at least triple that on wear alone - that's hefty amount. My guess is you don't even have a measurable pull. Personally I'd replace the sleeves - $80-$100 for a new set.

TOH

 

[Widget]

n8terry, The other member that replied to your post TOH makes and sells a excellent quality sleeve puller. Not sure if YT will let me post his url but here goes. If not i"m sure someone else will chime in with a link for ya.
http://mysite.verizon.net/oldhokie/windyridge/id3.html

 

[JohnMD]

This is not according to spec's but if there is any amount of ridge at the top of the sleeves then I suggest they be replaced. There are two types of sleeves, steel .o40 and cast iron .090. According to your year you should have the .040 but you should check before ordering parts.Piston, rings etc. are the same for both. I do not know if oversized rings are available but that does not sound like a good idea to me. The tool made by TOH will remove either type of sleeve. However the cast iron sleeves came out real hard on the one I did. There are spec's for the valve giudes but all I do is see how tight they fit. If the valve is reasonably tight in the guide it is good enough for me. I would suggest that oil pressure be a consideration on how far to rebuild. If you don't have 15-20 lbs pressure hot using 30 wt oil it may be time to replace all the bearing and rebuild the oil pump. All that said I replaced the rings,rod bearings, rebuilt the oil pump and hand lapped the valves on a 1949 N 20 years ago that has never carried more then 5-10 lbs of oil pressure hot and have ran it hard for all these years with no problem. All depends on how much time and money you are willing to put in to it. Make sure you have the FO-4 manual before you tear in to the engine.