These Knucklehead style cylinder heads are precise reproductions of the stock counterparts and show all the small details like cast-in number tags and foundry markings. Thus they make for great replacements for your worn top end or to build a factory look-alike engine. They are manufactured after 1940-1947 heads with large intake ports. The pre-installed, but unmachined valve seats are sized for stock intake and exhaust valves and hardened for the use of today’s unleaded fuels.

Reproductions of Knucklehead style cylinder heads, cast from aluminum. The advantages of this material are obvious: besides the significant weight savings of approx. 4 kg per head, they dissipate heat much better than their cast iron counterparts. That's why the Motor Company implemented aluminum heads on the follow-up Panhead series.
On the down side you have a somewhat lower robustness, which is not really relevant on stock motors, however, when high revs and compression rates, or nitrous and supercharging come into play, well, that’s a different story. So, as always, race oriented riders and their mechanics have to decide which route they would follow.
The design closely matches that of 1940-1947 heads with large intake ports. But technically the Cannonball heads are not just 1:1 copies of the cast iron patterns. That wouldn't work. For a safe operation of both valve seats and guides the manufacturer established additional material around them to securely hold everything in place. Valve seats are pre-installed and sized for stock intake and exhaust valves, but unmachined. They are hardened for the use of today’s unleaded fuels. Steel inserts for the head bolts feature factory threads. The heads show all the small details like cast-in number tags and foundry markings, so they make for excellent stock replacements or for building a performance engine with factory look when you camouflage them with black paint.

A typical problem of original Knucklehead cylinder heads you find on swap meets are missing tabs for the rocker housing. These cast iron weld-on or solder-on tabs might help you make a good deal. They are made exactly like the original tabs and after you have drilled and trimmed them to length you just have to find a good welder to put them back onto your heads.

When the factory started to omit the priming cups in late 1936 such plugs were installed to close the existing holes in the cylinder heads. These exact duplicates replace your missing, worn or wrong parts. Of course, it can also be used as a drain plug.

Authentic reproductions of Knucklehead rocker housings as used by the factory from 1938-1947. You can install them as they come or brush and polish to your personal liking. Precisely machined on CNC equipment for a perfect fit.

If you ever tried to locate the original counterparts on swap meets, you soon will like these very accurate and precise reproductions. Once installed you can hardly tell the difference.

This adapter was used by the factory 1938-1940 and is required for all early type rockerboxes on the rear exhaust position to seal properly against the valve spring and rocker arm covers.

Hard to find rocker arms and shafts remanufactured by S&S. These high quality rocker components are the same as S&S uses in the KN- Series engines, and will fit stock Knucklehead engines as well since they feature the the stock 1:1 rocker ratio. Each complete set comprises four rocker arms, rocker shafts, washers, spacers and special O-ring seals. The shafts are also available separately but are not compatible with stock rocker arms.

Replacement rocker arm shafts for all 1936–1947 Knucklehead engines. Can be combined with original and S&S aluminum valve spring covers. Sold as sets with four shafts.

Replacement rocker arm shafts for all 1936–1947 Knucklehead engines. Set with four shafts.

Replacement rocker arm ball stud for all Knuckleheads. To be cold riveted like the OEM  part.

Complete kit with four left side rocker arm shaft nuts and washers.

Exact duplicates of the large rocker shaft nuts. They feature the low profile design of the original counterparts.

Complete kit with four right side nuts. Improved design with integrated O-ring seal.

Accurate reproductions of the original rocker arm thrust washers and packing washers.

Complete kits of tins for the valve springs and rocker arms. The selection includes the early "baby food jars" and the later 1938-1947 covers, which include all small parts like bolts, strips and gaskets. These exact reproductions are ready-to-install with oil lines and nuts attached.
The installation, nevertheless, requires a skilled mechanic.

Beautiful reproductions of the stock Knucklehead rocker arm cover caps used from 1938-1947.

Reproduction of the reinforcing threaded screw plates.

Reproduction of the original cam cover-mounted fitting used with the rocker feed oil line on Knuckleheads 1936-1941 as well as engine vent line on Knuckleheads 1936-1937 and 45”/750 cc models 1937–1952.

Complete kits with one feed line fitting for the cam cover and two rocker housing fittings.

Rockerbox drain tube fittings for all Knuckle-heads 1938–1947.

Exact reproductions of the stock Knucklehead oil feed lines which connect the gear cover with the rocker housings.

Precisely pre-bent replacement oil lines and nuts for the lower valve covers. They come as a set of 4, with nuts and the correct flare at the rockerbox end. Need to be soldered in just like the originals. The nuts are also available separately.