Bore it or not?

Ok, '68 3000 gas motor - dropped #3 exh valve and punched a hole in the piston.

Checking the bores I've got a .002-.004" ridge a little more than 1" down the cyl.

The manual specs 4.2007"-4.2032" and I've measured a max on #3 at 4.217" at their "W" measurement 2&3/4" down the bore.

The other cyls are at 4.205 and 4.206"

Do I re-hone and put a stock piston back in with new rings or do I take the block to the shop and go with .020" oversize pistons?

Opinions?

I know I will catch flack for this but you could just bore #3 It can be done in the tractor. I did it on a TW10 that the air filter senser allowed it to pull dirt into the back cylinder it had to go .040 over. It run fine for the next 5000 hours that I owned it.

Hi I'm not sure on that gas motor but with some
of the ford diesels you have to be careful when
you bore them out,that the block doesn't go
porous in the bore, due to corrosion/ fords
junk castings.
Some of those motors were famous for it and it
could happen instantly or after a few weeks use
after doing the work.
I know a guy had that happen to a 76 series
tractor motor in his farm handler, they bored and sleeved it on the second go round.
Most guys in the know, now seem to bore them over then
sleeve and bore them back standard to stop
this, the first time.
Maybe someone else will confirm one way or
another for your motor as I honestly don't know.
Regards Robert

The gas vs diesel cavitation issues doesn't have a definitive answer, its been talked about here before.

Our local machine shop here will bore a Ford, but at your own peril, he doesn't want to hear it if it goes into the water. He recomends boring and sleeving back to standard for any of them.

I'm not worried about the porosity problems so much as:
Do I fit new rings in the ALMOST in tolerance cyls and file fit a set of .020 over rings on the worst cyl, button it up and run it?

Or, yank the motor, take it to the machine shop, bore/hone the whole thing for .020" over pistons and have a brand new engine in a 47yr old machine that will be used on 3 acres moving dirt and firewood to the tune of less than 100hrs a year?

Hi you'll be worried about it if you bore it
and put over sized pistons in and it does go
through without a sleeve. Maybe over sized
rings would work. There are a whole load of
half way fixes to this.

I used to sell parts for a company that did
standard rings that would go in a worn bore.
they had a slight bevel on the top ring so the
edge didn't hit the wear ridge , and break the
top ring.
You could do what you suggest or just put
standard rings back and hope.
The worst options are is it burns oil, has no
compession or breaks the rings or seizes on a
cylinder if it's not clearanced right.
I will do as a customer wants here sometimes
within reason, depending who he is and if it
will cause problems if it wasn't right after.
Basically in that deal the guy has no warranty
( written and signed on the bill) and loose all
right to go to the coffee shop and tell
everybody it was my fault it blew up!
I get your point on hours and cost But if it
blows up you got nothing, if you wanted to sell
it, a good motor in a tidy tractors worth the
money, guys will use a worn out motor against
you on the price!.
Regards Robert

waiting for Bern or Rod to jump in on how far these blocks will go,

I would resleeve the bad cyl. and if the price were reasonable consider resleeveing all three to standard. If too high resleeve the bad one only. Check pistons for wear and replace if needed. Hone and rering and life is good.

Ok, so the guy mis-quoted me on the price of the engine kit, he priced me a diesel - $357 the GAS one is $608 with no bearings! That's going to put me into the motor at a grand!

C'mon, someone out there has one of these stashed behind their workbench don't they?

Where are you located? there's one on fleabay in Farmington, KY. Claims it's "remanufactured" with new sleeves, with a $500.00 "Buy it Now" price.

3000 gas engine block on fleabay

It's always a tough call.
The right way to do it of course is to bore and sleeve back to standard. But around here you wouldn't get that done - with parts - for a grand.
More like $1500+.
Then you'd yave an engine that was good for another 50 years.
I still haven't seen any first hand evidence of cavitation on a gasser. Most of the fellows here are running diesels where yes, cavitation is a problem. So you might get by with just a .020 overbore and new pistons. That would probably be $3-400 cheaper.
Another thing is; I haven't heard you have checked the crank yet. I suspect you are loathe to pull the engine but you really need to drop the pan to determine the condition of the lower end.
The crank might be the deciding factor for me.
If it needs to be ground then the block needs to come out. If the block is out then you're in for a penny, in for a pound and might as well have it bored.
If the crank was good I might be tempted to just do an inframe on it. New rings, rod bearings and valves. Buy a .010 over ring set for #3 and file the end gap to fit.
Is that ideal?
No.
Is it a cobble?
Yes.
But would it run and make good power for a couple thousand more hours?
Of course it would.
It was running when it wrecked itself wasn't it?
So #3 might use a little oil. I could deal with that.
Another part of the equation here is you don't know the condition of the rest of the tractor - clutch, gears, hydraulics, etc.
If you spend $1500 on the engine will you have enough dough to fix other potential problems you find?
As for the SOS tractor you mention above, that would only tempt me if I could buy it cheap enough to swap engines between them and make one tractor out of two.
Some guys like those power shifts. I've never worked one enough to think they are special.
Call that contempt prior to investigation if you wish.
But give me a crash box and I'll be happy.

UD nailed it - I don't know the condition of the rest of the tractor's systems. I'd hate to drop $1100 rebuilding a motor and find I need all the pumps rebuilt/replaced.

Pan is coming out, plastigage the rods & mains..... If it's bad I'll be in the corner crying......

There's one in KY that smokes for $1100+ freight....

I'm hoping to do the valve job, swap a piston into #3, grease the old head gasket and reassemble to see if I can get compression up to something runable (90-100?)

Meanwhile the wife didn't kick me when I mentioned that SOS unit

will most certainly break the new rings... If cyl is worn more at bottom than in middle. or worn more at top than the middle.. If worn evenly top to bottom, no prob, but that is not the norm. and the rings will break. The old fords of that era would wear at teh bottom when the crank bottomed out, the piston momentum would try to make the piston turn sideways on the wrist pins.. So we always saw a belled-out wear pattern at the bottom of the stroke, sideways to the crank direction. And iirc anything over 12 thou would snap the rings 7 thou was the minimum reccomended run out.. but then that was in the 70s.. and I'm pretty fogged up nowdays. So dont put much faith in my figures.

Thanks Bill, .007 puts cyls 1&2 as "workable" but the bell of #3 is 7-14 thousandths out of even that "acceptable" measurement.