Truth is in stock form this is all true, but you only have to make a few adjustments to make a difference. Lets start in the beginning, the LA engine is the same from 273 to 340 except bore, all have 6.123 rod, 3.31 stroke, and all 1971 and earlier LA engines had steel cranks. 318 have 3.91 bore, 340 4.04 bore, 360 4.00 bore, and heads are the big difference period. You cant run the big valves heads on 273 without notching the cylinders, but it can be done, the rest you can. So lets stick with the 318, X, J, and 360 heads have almost the same flow so dont work so hard at it. Get a set of 74 to 88 360 heads and put in a set of 2.02 1.60 valves with good springs when you have them machined, clean up the casting in the ports dont grind them. Note; why 74 to 88 360 heads - they have harden seats for unleaded gas, they flow as well as the X heads, and can be opened up to 2.02 without replacing the seats, and are cheap and plentiful. Bore it to 3.94 (.030 over), put in the Keith Black KB399 KTM30 piston and rings (I have been running this for years on low octane gas, so save it everyone, Chrysler has the most efficient combustion chamber of this time just run good fuel when you race it) 2.02/1.60 heads, full groove main bearings, good rod bearings, cam bearings, Purple Shaft 484/284 cam, Edelbrock RPM Air Flow intake, with Edelbrock 750 cfm performer carb with Elc. Choke, headers, 340 (with good bolts) or eagle I-beam rods, deck the block to make it flat, and balance the rotating assembly, High Volume Oil pump and a 7qt pan, roller rockers, and call Hensley Performance in Knoxville Tennessee (ask for Ken or Matt) before machining, and ask for the Purple Book it will show you how to fix the oiling problem. This combination will make you between 400 to 410 hp with 430 fpt, this out of a 318 (325cid). Foot note; Chrysler never had a designated 360 casting until 1974 so the 71, 72, and 73 are 340 blocks with 360 casting marks (Thick cylinder walls) it is the poor man stroker, the early 71, 72, 73 - 360 can be bored to 4.08 Remember it is a 340 block so it is a 040 340 with a 3.58 stroke is a 374 cid small block kind of cool and very fast. And if you are using a light car (A-Body 3200lb or less) run a 904 trans with the deep 272 front gear and 4.30 rear gear, 2800lb car very low 11s. This will give you a hard launch and a great top end charge in ¼ mile. You can build this for about $1500.00 or less. I am a school teacher I just stayed at a Holiday Inn Express last night LOL good luck and have fun.
