The Wallace predicts that 78mph@3500 raceweight is 258 hp.
That Dart should be up in the 90s mph; 93 would be 438hp@3500pounds, (which is where my 367 sits.)
Which means, at 258, she is down some 180 hp, or over 40% !
So, IMO, something serious is going on here.
IMO
The 78mph @ over 6000rpm in Second gear is telling us that the top-end is weak.
The 60ft is telling us that the engine is weak at low-rpm.
Cam timing always swaps one end for the other, so you can't have two weak ends with bad cam-timing;
Therefore;
IMO, the engine is just plain weak.
IMO, This is further supported by;
A
[email protected] cam on a 108LCA, that may be in at around 106 for an Ica of 70*, that is still making 150 psi cranking cylinder pressure; seems pretty normal; therefore,
Cam timing is Not something I'd be thinking about just yet and
I'd be looking elsewhere, like;
>The overlap period of that cam is gonna be around 72 degrees.
Shorty headers are gonna kill the overlap tuning, and with it I'll guess 30 hp on that cam, or more.
>Detonation will also kill power way worse than a few degrees sub-optimum Power-Timing. let me guess 20 hp
> the low CCP is another place power is lost, and I'll guess 15 hp.
>But even if you add up all the estimated powerlosses, that only totals 65 hp; and we're looking for almost triple that !
There is NO WAY that cam-timing is gonna steal 115 hp.
nor will secondaries failing to open.
> AFR problems
IMO
7 inches vacuum, with that cam @25* Idle-Timing is telling us something, and together with the plugs, she is not a happy engine. I would expect more vacuum from that combo. like 11 or more.
(Shoot, the 292/292/108 (249@050), in my little 367 pulled 11in no problem, with a well placed Transfer slot exposure.)
IMO
that 3000 stall is not that big a deal. With 4.56s, by 20/25 mph, she should be pulling lots of rpm. A 440 in an A-body, and weak bottom end, should not be heard in the same sentence.
If I had to guess, I'd be looking into one or more of;
a flatted cam/valve-float/lifter pump-up, or
problems in the ring-seal, or
poor-flowing heads.
Or some combination.
After that is fixed, whatever it may be,
then, if it was my race-car, I would:
ditch the shorties; like in a heartbeat;
rework the distributor,
send fresh cold air to the carb,
make sure the fuel-system is good to a minimum 438hp, lol,
and then, begin to fatten up the AFR.
Happy HotRodding