Four Cylinder Flathead - Big 'Banger Theory

Standout elements of this engine are the chain drive and the fabricated front cover. The chain runs inside the cover from the cam in the block up to a tensioner and then to the overhead cam.

The chain runs inside the cover from the cam in the block up to a tensioner and then to the overhead cam. Chain length has to be accurate and involves determining the diameter of all gears. Installation is tricky, time consuming, and fun to watch other people do.

H&H made this adjustable and accessible chain tensioner, consisting of a sprocket gear on an eccentric hub. All you have to do to adjust tension is rotate the assembly-easy since the cover plate features slotted holes. It's not a Joe Gemsa design, but a variation and improvement on Gemsa's tensioner.

When the helical gears are rotating fast, the cam wants to move forward. Henry Ford used a spring and plunger device to push back on the cam. H&H's solution is a small aluminum threaded plunger for the lower drive gear with a trunnion bearing at the hub. The plunger provides resistance to cam thrust, and is held in place by an outer cap built by Max Sr. The nut on the outside of the cap adjusts tension. Turn the nut until you feel resistance, back it off a touch, and tighten down the cap with Allen bolts. Trick piece.

Gemsa cast his 'banger heads with a large opening at the back. "This was their version of the freeze plug," Max Jr. explained. "Instead of running freeze plugs like you see in heads today, he cast them wide open. The open end was sealed up with a plate." You can see the plate at the upper right in this photo. H&H set up the cooling system to run water into the engine from a port on the driver side of the block, where the lower neck is located. A braided line delivers cool water into the back of the head.

Gemsa's heads were designed to run at high compression, somewhere between 9.5:1 and 10.5:1. H&H uses these Arias pistons with unique domed tops to bring up the compression. This four-banger runs in the neighborhood of 10.2:1 or 10.25:1 compression.

This Wico Series C mag is an original piece from a swap meet. It drives off the cam gear, on the same system as the crank gear; 2:1 reduction gearing in the magneto keeps it spinning at half crank speed (equal to cam rotation). The Wico is infinitely adjustable; Max Jr. set it up for about 24 to 26 degrees advanced timing. Although, much higher than that and he's risking detonation, he warned. There is hardly any room between the Wico and the oil filter and pump, so the pump was repositioned, the delivery hole plugged, and the line rerouted to the other side of the assembly.

A billet adapter allows the use of a cast '32-36 style water pump. The pump is a brand-new casting, mounted off the front of the cylinder head, fabricated by H&H.

These forged port exhaust headers just happened to be in the shop, waiting for the right application. They came off of a 1,000hp dragster motor that had ended up there. Max Sr. cut the tubing off the race car, gas welded them up, and had them chromed. At approximately 2 1/2 inches in diameter, they are actually larger than the exhaust ports.

A pair of Stromberg 97s atop a Gemsa intake manifold will handle the induction duties.

Max Herman Jr. and Max Herman Sr. from H&H Flatheads, proud of this four-banger, built following the way Joe Gemsa did it. He' be proud too.