Quote:
Originally Posted by takid455
The 2.73 & the 1:1 5th are the cruising gear. 1st gear in that trans is a 3.27. Had a 4.10 1st which made a harsh 1-2 shift. 2nd gear was 2.20 ish . The car has been together for 13k miles with the FT HC03 & was pretty happy. I know the gear change will hurt some acceleration, but I'd rather the stronger top end than go to a lower rear. Car is typical 2nd gen w/ no weight saving measures. Doing some work on it & juggling the idea of changing the crank / internals because we can. The SD rods have been resized with ARP bolts connected to SRP forged pistons. Part of me says just go all new for piece of mind. The other part says, save what you can & upgrade the crank. I do like the shorter piston theory as long as it can remain stable. Realistically for the use of this car, either selection will be fine. It'll be street with occasional 6k blast ripping through the turns. That's what the old cam would hit.
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Butler has of the self Ross pistons for 6.7 rods. They are BBC and would go with a steel crank with 2.20 rod journals.
You could even go with a 4.375 forged crank and 6.635 (near Pontiac) BBC rods and custom piston.
You would feel the difference in tq with your heavy car.
All kinds of things you can do. But if it involves Pontiac SD rods you are stuck with 4.21 stroke,3.75 or 4". And thats not so bad.