Some "food for thought" on the 250-i6 buildup:
I have one of those computer programs for engines, it is pretty well rung out against a lot of dyno data - mostly v8 but as much i6 and i4 as I can find too (always looking for more - )
Since I am planning a 250 and a 292 build right now myself, I found the Langdon iron in Leo S' book and made a guess as to what it will do. Given that I computed the motor you might be building.
When I compute the stock 250 Chev 6 here is what I get - GROSS numbers at the flywheel, 60F air, 29.92 pressure, no exhaust or fan or air cleaner etc ie the "old pre-1972" ratings:
Torq 214 at 2000
Torq 227 at 2600
Power 152 at 3700
Maybe accurate maybe not but now compare to what you might build and how it computes.
I added the Langdon iron, a Clifford 4v and 500cfm carb:
Torq 226 at 2000
Torq 241 at 3100
Power 178 at 4100
My instinct tells me the Comp 260H cam is much better than the stocker - I added this and the computer said:
Torq 206 at 2000
Torq 240 at 3700
Power 207 at 4800
So it lost a little at 2000 but really goes up on the top end. Depends on your use I guess - there is a smaller cam at about 194/204 duration at .050 it might be better for a work truck 250 -
Then I changed from the Clifford 4v to the smaller Offy 4v. This is where I trust the computer the least, but it got me:
Torq 211 at 2000
Torq 241 at 3500
Power 202 at 4700
Gained low, lost high.
Well, short of some dyno data (not much of that in Leo S' book either, very scarce for the Chev 6) those are my best guesses at least something to think about - - -
