Yet another 273 build advice thread!

Here is the 340 cam in a 273 at 1000 ft elevation, and in at 110. The Ica according to the advertised intake duration would be 64*. Because this cam is known to have long slow ramps, and IIRC Wrmryder may have mentioned close to 300*intake duration at .001. If that is correct, then the difference from 268 to 300 is 32* and half may go to each end or 16*. On the off chance,lol, that I remembered it wrong, I will arbitrarily add just 10* not the 16* or so that is called for. So I'm calling the Ica, 74* so; close to sealed but may still be leaking
Static compression ratio of 10:1.
Ica of 74*
Effective stroke is 2.33 inches.
Your dynamic compression ratio is 7.33:1 .
Your dynamic cranking pressure is ............................140.55 PSI.
V/P (Volume to Pressure Index) is ............................ 81VP
So first notice the pressure is just 141psi, with an Scr of already 10/1. It will take another full point of compression, namely 11.1 to get the pressure to 160
Second; notice the slanty VP. Off idle this combo will pull about as hard as a slanty and continue to get a lil better until around 3000/3500 when the lil 273 will start trapping mixture properly. To combat that, she would need some combination of higher stall and IMO, to be fun, a lotta gear. For best results I would recommend a manual 5-speed, and whatever gear it takes to power peak a couple of hundred rpm below 60 mph in second gear.

I built a combo similar to that, but with a teener and I used the 273 solid lifter kit, yes on the hydro cam. You know, cuz I thought I could get away with that on that looooong-ramp cam. With the lash, I could control the Ica to something a lot lower than 74*. It worked out not bad except the fuel consumption was insane, and it took a 2800TC to get moving with 3.23s. I installed this in a 71 Monaco base model. Between the weight and the low cylinder pressure, it was still a dog until wound up, then it turned into a beast, perfect for downshifting and passing at 65 mph ..... but it wasn't good for much else. I shouldda known better cuz I was already in my late 20s......... but I had this 340 topend looking for a home, and a smogger-teen shortblock, and the 360 in the Mon was burning a lotta lotta oil....... you know the story....


Just for the heckuvit, lets put that cam into a 360
Static compression ratio of 10:1.
Ica of 74*
Effective stroke is 2.53 inches.
Your dynamic compression ratio is 7.36:1 .
Your dynamic cranking pressure is ................................... 141.33 PSI.
V/P (Volume to Pressure Index) is ....................................108VP; still a dog,will need a TC and gears
Check out the 33% VP increase, at roughly the same pressure. .
Lets crank up the pressure

Static compression ratio of 11:1.
Ica of 74*
Effective stroke is 2.53 inches.
Your dynamic compression ratio is 8.07:1 .
Your dynamic cranking pressure is...................................... 160.08 PSI. good for iron heads and best gas
V/P (Volume to Pressure Index) is ..................................... 122VP; This is like a 5.2 Magnum (124VP), TC or gears, but not both

And next lets put some aluminum heads on it and crank up the pressure some more
Static compression ratio of 12:1.
Ica still 74*
Effective stroke is 2.53 inches.
Your dynamic compression ratio is 8.77:1 .
Your dynamic cranking pressure is ..................................178.90 PSI. Good for aluminum heads and 87gas
V/P (Volume to Pressure Index) is ................................... 137VP; OK now the dog is dead and buried. Drop it in and drive