Just how quick were the 273 Commando's in the Quarter-Mile.
In the 90's and while I was building my race motor (360), I ran my dead stock 318, 2 barrel 904 with 3.23's in an Aussie a-body Valiant. it ran a 16.8
We put a 600 Holley on it and a street torker or something and it ran a 15.2 with no other changes.
My current 273 should run 12's..
Well let's look at that for a sec....Quoting from the Direct Connection Performance Book, bulletin #40,dated 1977, and titled: Mopar Bracket Racer Science (price $1.00 back in the day).
Let's say a 12.7 car.
From chart #1, with an unlimited chassis.("an unlimited chassis is representative of what would be used in Super Stock"). This minimum ET (12.7), accompanies a trap of 104mph with an automatic.
From chart #6, this 104mph requires a W/P of 11.0/auto. So that indicates you will need to get your car to run 11 pounds per horsepower.
From chart #4, we see that a realistic raceweight for the 63 to 66 Abodies with A engines is 2900lbs +/- 100.
Now doing the math 2900/11.0=264 HP....Shazzam!
Now to build a 273 to get 264 hp is a whole 'nother story.This is 264/273= .967hp/cid. This is doable but..... takes it near into race motor territory(but then so does the unlimited chassis).
The 273-4bbl engine, from chart #5, had a "rough approximation of the installed,production power level" of 200 to 215hp.(This same chart lists the 340 as 275 to 290, and more importantly, the 318-2bbl as 150 to 170hp). So pumping it up to 264, is about 57 hp additionally.Furthermore 208hp/273=.76hp/cid, a relatively mild figure.
So now to the build. Recall from page 1,that in bracket racing;"there are no rules- you can build the car and engine any way you want". So cam, heads, and Throughput is the plan. You are gonna need to rev this baby. Doable? yes. Expensive? yes.
Now, let's examine the unlimited chassis for a sec. Unlimited. This means the best of everything, and everything working the best that it can. You are looking at gears, a TC, slicks, springs and bars, shocks, everything tuned to hook.All the while staying light, or lighter. And stop at the big end, and steer. Doable?yes. Cheap?no.
But let's say you want to drive this car on the street, cuz, you know, you got all this money in it, and the weather down-under is fine, and it's calling to you. Well, with that pipey engine, the hi-stall, the mega gears, and the SS springs, and the nose-down front, and the loud stripped interior/no mufflers..........um, probably not...........
I know what I'd do, um did............G'day mate, and all the best to you.
