Reply to "Closed-chamber heads"

Hello JWR! I ran Your before and after data through the Desktop Dyno and here is what it 'spit' out. First; The compression ratio in '71 was advertised at 11:1, but was more at 10.7:1 and the Horsepower for that year was 'Rated' at 330 (at the flywheel, ALL the figures to follow are AT THE FLYWHEEL!!). In '72 the comp. ratio was lowered to 8.6:1 and the '72L was lowered even more, to 8.0 (The same as My '74L) So I will give you the figures for the '72L at 8.0:1 Comp Ratio. If you do NOTHING MORE than change to the 'High Compression Heads'(leaving the dished pistons in, and NO other changes), Your ratio will climb to aprox. 9.5:1 and the valve size will be at 2.19 Int. 1.71 Ex. (I don't know if the '72 heads already had the larger valves or not). These are two of the most significant changes you can make to the 'ENGINE' other than a Camshaft/Lifter change and a Carburator/manifold change. You Already have 'Tube' Headers. Your HP and Torque will raise from 246/337 @ 4500/3000 to 274/362 @ 4500/3000 RPM respectfully. This figure is calculated with the stock 'Dual Plane' Intake manifold and a 600 CFM Holley. A change to a 750 CFM will net 286 HP @ 4500-5000 rpm, with the Tq at 368 Lb/Ft @ 3000. When you go to a Single Plane manifold, as I recommend, the reading is 303 Hp @ 5000 and 362 Lb/Ft @ 3500 RPM. If you were to make ALL of the improvements that I did to My Boss 358 (.030 Over 351C) You can achieve 529 HP @ 6500 and 463 Lb/Ft @ 5000. And that is with a Hydraulic flat tappet cam. A 'Solid' Lifter cam will make an emmense improvement to 558 HP @ 6500 and 483 Lb/Ft @ 5000-5500. We all know that the 'Roller Cam' is King! Bringing the figures up to 590 HP @ 7000 and 506 Lb/Ft @ 5500. And that is with a single 4 Barrel Carburator! A lot of people will argue this, but, this program for what it is worth; 'SUGGESTS' That Stroking the 351c; although builds more Tourqe and at a much lower RPM, does very little for increasing Horespower. I.E. for the same bore of 4.033, a stroke change to 4.00" increases '0' Zero HP. While a stroke of 3.85" adds 4 HP. All this HP STILL 'Peaks' at 6500 RPM. With the Tourqe of 537 Lb/Ft for a 3.85" stroke and 549 Lb/Ft for a 4.00" stroke; Both peaking at 5000 RPM. Beleive it or Don't! This program is + or - 4.0%. I have ran the figures of numerous other members, who have actually had their Engines Dynoed and the results have been 'Right-On'! Being with-in 4-5 HP. This should help many of you decide on some of the parts you wish to lay your money down for. That is all; good-Luck with it!