Dome pistons

[john2189]

Is there a way to tell if my 72 has dome pistons without removing the head? What year did they start the dome pistons? I tried doing a search but couldn't find anything.

John

[inairam]

Look at the engine serial number. The dome piston introduced with engine sn 264567 and above. ~ 1968 sp your 72 is 4 years into production

To find engine serial number http://www.tmtractor.com/id/id_003.htm

[john2189]

Thanks, my engine must have been replaced. It's serial is 249945 so I'm guessing it's flat top pistons.
John

[inairam]

according to the cub tractor database it looks to be out of the 1965

Tractor SN 226359
Engine SN 249751
First of month, Aug-65

Tractor SN226489
Engine SN 249951
First of month, Sep-65

[john2189]

Ok it does have red under the yellow.
John

[john2189]

Ok my motor needs rebuilt, so, I assume that the high domes will work. Right? Is there a reason not to use them?
John

[tst]

they will work, just double check head clearance, if the head has been shaved in the past sometimes just need to sand a little of the dome

[staninlowerAL]

Somewhere along the way I've read that the connecting rods are different. Someone like Jim Becker can probably tell right away if that makes a difference if you're changing to dome pistons.

[tst]

the rod bearing width was changed so the rod was changed, flat top and dome style interchange, have done this many times

[Jim Becker]

sometimes just need to sand a little of the dome

Better to take a little off the head if needed. Keep the moving parts in balance.

[john2189]

Thanks for the info

[artc]

the connecting rods are different. but it will only matter if you are trying to connect the wider bearings to a newer crankshaft THAT HAS NOT BEEN TURNED. the problem is that the wide bearings will lock up the engine due to the radius of the edge of the crank journal.

if its been turned, they tend to cut the radius out.

so, the rods can be used on either piston, but be careful of the crank rod journals.

[john2189]

so my original rods and crank will work with domes, even if I need to get the crank ground?

[artc]

yes