ULH Cylinder queation

[Robert Luland]

Boys I need some guidance here. This has to do with ULH cylinders. Are 74 and 80 cube cylinders the same with one being bored larger or are they different cylinders? I read Bruce’s paragraph on this subject but obviously I’m missing something. Thanks guys, Bob L

[Jerry Wieland]

The 74 and 80 13 fin cylinders are the same casting. 80 cylinders were bored to 3 7/16 (vs 3 5/16") and relieved around the valves.

Jerry

[Robert Luland]

Thanks Jerry but what do you mean relieved around the valve. I'm not retarted, just slow.

[Chris Haynes]

Thanks Jerry but what do you mean relieved around the valve. I'm not retarted, just slow.

That means that several thousandths of metal around the valve is ground away to provide a better flow towards the bore.

[Steve Slocombe]

The 13 fin cylinders have 120-37 and 120-371 cast in the front/rear base flanges. They will be used on the 1937 Big Twin flatheads and the 1938-41 ULH models. The 11 fin cylinders have 120-38 and 120-381 cast in the front/rear base flanges, and were used on the 1938-48 74 cubic inch flatheads.

[Jerry Wieland]

Bob Cylinder on the left is ULH and the cylinder on the right is UL - both 13 fin.







Jerry