Copyright WWW.DBBP.COM | updated 29-December-2003

Auguste Dionne sent me an article from Street Choppers (September 1981)
about the legendary Harman 120, I have tried to turn the photo's of
the article into a readable piece of text but it was much to much for
me to type all at once (I still type with one finger!):

The Harman cases are cast from 356-T-6 aluminum with seamless mild steel inserts locked into the casting. The deck height is 9/16" inch taller than stock and the right hand case is 3/8" wider in the flywheel area to accomodate a larger bore. The big inch street engines are produced using the stock stroke and crank which is the only stroke to be used in these engines for street use. The lower end assembly does require the use of Harman's 3/8" longer pinion shaft and the stock rods must have the brass pin bushings to accept the larger .977" diameter wrist pin. The remainder of the crank assembly can be left as stock HD or 4" stroke S&S.

The lower end is machined to use all the stock components including oil pump, lifter blocks, bearings, cam etc. John recomends the use of a fairly wild cam for ease in starting and boosted top end. The engines have plenty of low end and something down the lines of the Leinweber L-6, Sifton Outlaw or Andrews "M" has proven the hot tip.

Harman's barrels are machined from 65,000 PSI Ductile iron featuring large cooling fins and a bore of 4 3/8". Each cylinder is also fitted with an O-ring seal to the head rather than the standard gasket. Oil return galleys through the barrels return oil from the spring pockets in the heads down through the front and rear of each cylinder and drain it just below the oil ring's travel point. This drainage onto the piston skirt helps prevent scuffing.

Presently Harman is using Arias 8.5 to 1 forged pistons with .927" pins but may be switching to cast units in the near future. The pistons feature 3 ring construction and have longer skirts 2 1/4" below rings, than stock. The pistons are also notched for use with the high lift cams.

Cylinder heads are cast from 356-T-6 aluminum and are finned to match the cylinders. Intake valves are 2 1/4" Chrysler Hemi type while exhaust is handled by 1 15/16" Manley. Exhaust guides fitted are steel Manley's while intakes are 5/16" Westons. The heads as they come from Harman are set up for dual 40mm carbs. At the moment John has found much success with the S&W "Blue Magnums" but any 40mm Dellorto etc. can be used. Leinweber springs and retainers must be used and the heads will accept any cam currently made for the 74'. While stock rocker boxes are used they must be shipped to Harman stripped, along with the lifter blocks for machining to a slightly steeper angle. Charge for this service is $30.00.