want to argue? increased bore kits

I have not heard much pro's and con's on increased bore kits. I have had mixed results. In 1950's we had a WC Allis with 4 1/8 LP pistons. we used regular gas but would like to have had Ethel.Was a great runner but hard to start. Would pull 2 14's in third. Engine should run about 1350 I ran mine 1700 RPM until it threw governor weights. I have an M farmall with 4 inch and it is a great runner but when I worked for Ford and later for AC they frowned on increased bore kits. I put standard new old stock in ny H farmall and I do not expect or get much performance from it but I like it. My opimion is with larger tractors cheap there is no need to go bigger unless you are into competetive pulling. Let's hear it from all!

Agree

I cannot overbore, but I put LP pistons in my MF65 gasser for a 9.1:1 compression ratio. I did not own it when it ran the stock 7:1 so I am not sure what the difference is. I have a short vertical exhaust and she cracks clean. More power than I need and I haven't broke anything yet. I run 91 octane for peace of mind. I don't think it would detonate on 87, but I am not sure I could hear it over the exhaust.

I can bury a 7 foot box scraper with it...

Aaron

One thing I learned decades ago is if you build it up on the top and stay with stock on the bottom sooner or later some thing is going to give. Increase RPM over what was meant to be and something is going to give sooner or later. Chev?GM learned that the hard way when they tried to take a 350 and turn it into a diesel with out beefing up the bottom end and many of them then blew out the bottom of the engine. Didn't take long for them to rethink things
Hobby farm

Those old piece of junk 350 diesels are part of the reason diesel cars aren't more common in America. GM did a good job of scaring people off of them for a long time.

Not enough head bolts doomed the 350 diesel, FAR more than any "bottom end' problems.

I had one of those in an '81 chevy impala. Greatest gas mileage ever, in a big heavy car. I actually wish I still had it.. 28,000 original miles 3 years ago.

With the overbore you are talking about you get maybe 5HP extra at best hardly noticeable.I've seen plenty of the AC engines running 1 1/2 times the original HP with no ill effects.

Aron Ford brought up a vital point. If going with more compression on a gasser. If the fuel octane is too low it's going to suffer pre-ignition, knock or detonate.
It doesn't matter how beefy the engine is. Detonation will crack heads, burn plug electrodes off, blow head gaskets,break rings, crack/burn pistons and beat bottom end bearings flat.

As an aside.
Anybody ever wonder too when looking at a failed two stroke engine. They see burned plug electrodes ,broken rings, cracked/burned pistons and beaten bottom end bearings flat.
Run that two stroke on premium gas and make certain the mixture isn't too lean.

I waited and bought a 1982 Buick diesel after they put in more head bolts. Ran 300,000 miles with engine never opened. The injector pump and TH350 tranny were other matters, though

I agree.I think whenever you overhaul one you could soup them up some,like whatever you can do with a stock motor,maybe raise the compression a little,turn up the RPMs a little,maybe use dome or lug pistons if they are available,but boring out the block and using way oversize pistons only if you are pulling it in competition.Maybe even bore the block a little if you want,just not so much it gets hot idleing.Most old tractors are OK for power stock,but a lot nicer to run souped up a little.

GM seems to be like a cheap company,like they try and do things with the same design for many years,for instance the 2 stroke Diesel.They could just as easy as anybody else built a diesel motor right,but no,they took the cheap route.Gave diesel motors a bad reputation.However,what I saw was most people that maintained their vehicles like they should had less trouble than people who kind of changed the oil when they felt like it.I think its a lot more critical to change the oil,maybe even pull the pan and look at the bearings,if it looses water,pull the head right then and replace a blown headgasket rather than run it till it quits and try and fix it then.Even if you did all that some of those diesels would bust a crank or something.Cheap is not always what you think it is.I think it would have been cheaper for GM to build a diesel motor from the ground up rather than convert a gas motor,but at least they can say they know now and had guts enough to try it.

Cooling capacity is the first thing that comes to mind when overbore is mentioned. How many cooling systems were built to take away the extra heat coming from the exta horsepower?

A neighbor claims their overbored Oliver 88 could pull 4-16's eight inches deep 4 mph all day long in our heavy soil. He claims they didn't do anything to the rad. First he said it had 62 HP then he said 72! I don't want to call him a liar but...... Jim

Ya but a few of the real early ones would come back with a broken crank shaft. The first few used the gas crank which was not heavy enough to handle the diesel. I know there where no a lot of them built like that but there where a few till they wised up