A few more extra ponies for that old Big Flathead won’t hurt and you will get them fairly easy with a set of these ULR cylinder heads, made from cast aluminum. While looking quite original on the outside they feature an advanced combustion chamber design for improved combustion and breathing. Chamber volume is 100 cc, giving 6.1:1 compression on a 74” and 6.5:1 on an 80” motor. Substantially more material allows for custom milling and pop-up pistons. Another update are the 14mm sparkplug threads (3/4” long) for modern and more common plugs.

Dyno tests showed 18% more power and 13% torque increase over a stock 1946 UL with medium compression heads, just by swapping over to ULR heads! Check out the dyno diagram! These are true rear wheel numbers, power was up big time and torque curve is impressive! Remember, torque is the most important figure with flatheads!