Hi,
Given that you have two engines, you could merge the parts from both to
get the best case. I'd use the early motor bottom end and block because
the rods are stronger due to them NOT being "drilled" like the later rods
(starting at CF1) and a few other things. However, if you have the "long
tail" crank, you might need to consider swapping in the laster crank and
flywheel. The reason that I mention this is that early flywheels are tough
to find and there are ZERO aftermarket early flywheels out there. If you
have a stach of early flywheels, then you can ignore the crank/flywheel
issue.
The cyl head on the later motor is better. Period. It's the same head that
the PI cars got from the get-go, so they flow "real nice" right out of hte
box. You would (of course) need to use the later-style intake manifold,
but that flows TONS better than the early one and the long runners of the
late intake should help the torque numbers on the motor.
The one thing that I would def. change on your early block is the oil
pump. The early pumps with the cast / angled pickup SUCK for two reasons -
the impellers are smaller and thus flow less and the inlet to the pump is
very small and easily blocked with "swarf" if stuff starts floating around
in your oil... a blocked inlet for the oil pump is pretty much instant
death for any motor. The late-style pump has the Mr. Microphone shape, and
barring a plastic bag in the sump, it's pretty hard to completely block
the inlet. FWIW, the factory mandated the new-style pump on any motors
that were worked on after the new-style ones came out... no doubt to
remedy warranty claims and the like.
But if your goal is to keep the motor one way or the other (early vs.
late), you should def go with the late motor. It's got a better head and
it has all the "improvements" and the only drawback is the wimpy
18-58-58-18 cam (at least I think that's the cam timing.) The late cam for
Fed. Spec. cars is pretty wimpy... so plan on a regrind to make some power
(or pow-wah as we say in Boston). Oh - if you have to rods out for
"sizing", get 'em crack tested and have them pay particular attention to
the holes drilled through the rod at the upper end bolt for cracks. If
your goal is to lighten and polish - crack test and use the early rods if
they are okay.
regards,
rml
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