[Nikotrans]

Well, I did pull the trigger on the rear end ration (3.50), and was ready to pull the trigger on the TKO 600 with .64 overdrive, but after talking to the Hurst Driveline technician about the transmission, I’m thinking I should have gone with a higher rear end ratio (3.70 or 3.90).

His concern is that with a standard 255/70 15 tire and my 3.50 rear end, my rpms would be around 1800 at 70 mph – a little low in his opinion – even with the Chevy 383 450/450 stroker engine. At 1800 rpm the engine might bog down during typical highway driving in overdrive – something I’d like to avoid.

Part of my problem is I haven’t settled on rims and tires yet. I want to fill up the wheel wells as best I can (without tubbing) and look like a “muscle truck” with a slight rake (wider tires and higher in rear). Yeah, I know I was asked about tire size before, but I thought I could worry about that later rather than sooner. It seems I didn’t give tire size the due attention it deserved when putting together my power train combo.

So, until I figure out my tire size, I’m putting the transmission on hold. I’d also like to wait for the dyno sheet on my engine so I’ll have a better idea of my engines sweet spot (I should have that next week). Once I have those pieces to the puzzle, I might have to ask my rear end builder to swap my rear end gears to something a little higher to get closer to an rpm range that my engine will perform best in.

The Hurst Driveline technician said I could go with a TKO 600 with .82 overdrive to compensate for my existing 3.50 rear end ratio, but without knowing what my tire size is going to be, it still might not be the optimum setup.

Having said all that, I would appreciate your thoughts about wheel/tire sizes to get the look I’m after and maximize performance. Then I’ll reengage the rear end issue.

Thanks for listening.

(This build is becoming twice as hard and twice as expensive – why do I still enjoy doing it?)