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Cub block

grandpa Love

grandpa Love

Well-known Member
Pulled the head off our latest wreck, a '48 cub. Will the pitting between the valves and piston be an issue? Will clean everything up good. Un stick and adjust valves. New head gasket......
cvphoto90579.jpg


cvphoto90580.jpg

What caused this?
cvphoto90581.jpg

Old head gasket ain't terrible.
 
Due to the 'LOW TECH' of the engine, you should be able to get it running. The erosion around the valves and in towards the cylinder will definitely shorten that engines life. Maybe down to 5 - 10 years if cleaned up properly. Cross your finger. HPH
 
Looks like rust pitting on the block.

Are the pistons iron or aluminum? Probably rust/corrosion on them also.

It may have sat with water in the cylinders at some point. Possibly from a leaking head gasket, or stored outdoors with open exhaust, flood.

What do the cylinder walls look like? Any pitting or evidence that water may have sat in the cylinders? Could have stuck rings.

Good chance the valve seats need to be ground, or at the least lapped.
 
Those intake valves are not very good. Have a shop put new seats in it and then replace the valves, will be better than new.
 
Can I JB weld the top of block? Cylinder walls look good. Ounce of oil will seep past pistons in about 24 hours.
 
Doesn't look like it would be a problem since the gasket area doesn't appear to be very bad. But yes if he puts a gasket on and it blows in a short time then the block would need to be machined
 
Is this one you traded the pony for? I'd replace and lap the valves. You do have a parts tractor you could rob some better valves off right?
 
The pitting will induce extra turbulence in the flow of the air/fuel mixture, causing a more complete atomization of the fuel and a more efficient burn.

There is no head gasket between the valves and piston, so nothing to seal. The pitting is irrelevant.

As for how long the engine will last, I don't agree with "5 to 10 years" unless you're using the engine daily and HARD. With as many tractors as you've got, I would say the engine will last as long as long as you need it.
 
Tucker, well.......the rest of the story. Sold the good cub we traded the pony for 2 days after we got it. Couldn't sell the Pony,but the Cub went quick! This is the parts cub. After looking it over we decided we could get it running!
 
Those exhaust valves gotta go. They are already on the ragged edge of being warped and burnt. Pop all your valves and look at where they contact the seat- you should have a nice smooth consistent band around the seat and valve where they meet. If not, you might need some grinding done. If you are lucky you'll just need a bit of compound to bed in your new valves. Its not a high revving, high compression engine so you dont need to go overboard, just get them to seal tight enough to hold a teaspoon of ATF without it draining past them.

The other rust spots are all in the combustion chambers, above the valve seats and away from the sealing areas that make contact with the head gasket. They cant cause any problems besides maybe lowering your compression ratio .0000000001% and giving carbon deposits a handy place to hold onto.
 
looking at the valve on the left in the first pic, the seat appears to be rusty.
I think it's a good time to do a valve job.

Problem is finding someone who can grind valves on a flat heat.

Years ago I sold my valve seat and valve grinder that does that kind of work on flat heads.

If nothing else, get valve grinding compound and lap in the valves by hand providing there are no rust pits on seat. If there are, you may need to replace the seat. Good luck.
 

I would use a dremel and smooth out the rust pits.
Reducing undo hot spot edges and not becoming pockets to catch unburned fuel or carbon deposits.
 
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