Information on the 273

The reason I like 273's are they have small port, closed chamber heads, that will flow almost as much as 360 heads. From 64 to 67 they had solid lifter valve train and cams, forged steel cranks, and bushed forged steel rods. Pistons are almost to the deck and nut sunk like the larger motors. In 64 and 65 they had a odd angled intake bolts. The 235 hp versions from 65 to 67 (Commando for Plymouth and Charger for Dodge) had a larger cam (but still very small) 10.5:1 pistons, a nice Carter AFB with a secondary velocity valve and intake manifold, Prestolite quicker curve dual point ball bearing vacuum advance distributor, 2 1/2 inch single exhaust with 2 straight thru mufflers in series, chrome air cleaner breather, and PCV cup, and black krinkle valve covers with finned aluminum wire looms. I always liked a high revving engine so I preferred the smallest engine with the best heads. Easy 6,000 to 7,000 rpm with a 260-268 duration cam. I always ran a 4 speed with the 273 so horse power always trumped torque. Lower gears will multiply torque if that is where you want to go. A High Performance 273 is a perfect engine for an early A with a 4 speed. 68 and 69 273s were a downgrade with the cast crank, hydraulic cam and valve train, and the open chamber 318 heads. However the good thing about the later 273 was the piston. The 68 and 69 273 pistons were .030 higher in the bore (to compensate for the open chamber heads) making them near zero deck. Then just add the earlier closed chamber heads and you get close to optimum quench and compression ratio for pump gas.

Compared to other Mopar small blocks, they are all very good and can easily be made into performance engines. Except for the 340 and HP 360s they had very small cams, and that, valve springs, and a 4 barrel carb is where to start. 340 was king, a 318 can run with a 340 if you use all the good stuff, 360s were used in pick ups and large cars, but like 318s can also easily run hard using the 340 stuff and they already have good heads.