37 ULH cylinder bore

[jorrow]

What is the maximum stock cylinders can be bored before they need replacing? Has anyone had good experiences from aftermarket cylinders? Also I have always heard stories of these early flatheads overheating at higher rpm's, if that is true do they modification to be used in normal everday use? Thanks, Jeff

[bmh]

You need to speak with Paul at American Cycle Fab. 570-752-8715. He is one of the most Knowledgable flathead guys around. I can pesrsonally recomend him and his shop.

[T. Cotten]

My last ULH ran cool and strong at .070" over.
(even with powdercoated cylinders!)

It is manditory, however, to bore a couple of thou under the piston size, and use a base stressplate when hone-fitting for the final piston clearance. The spigots will distort as much as three thou inward at spots, and three thou outward at others.

If a stressplate is not used when honed, the piston will rub the spigot as soon as you bolt it together.
That's where all the horror stories came from.

It is always prudent to measure the remaining wall thickness beforehand, of course.
A simple old-fashioned caliper with the spring removed and the screw reversed allows one to inspect the thin spot above each base stud flange. Just carefully set it by feel, and then measure the gap with a dial caliper or feeler gauges.

.070" remaining has proven safe.

Good luck!

...Cotten

[jorrow]

Thanks Cotten and Brian for the great advice. Jeff

[Chris Haynes]

Here is a set of NOS 1937 cylinders.
http://cgi.ebay.com/ebaymotors/ws/eB...TQ:MOTORS:1123