Quote:
Originally Posted by gthompson
I have the same set up as you and I have been going back and forth about going with the .82 or .64 OD
I have been reading a ton of posts from here over the last year
I have a 427 aluminum FE (505 Hp) and the 4 speed top loader with a 3.54 rear end
At 70-80 mph the engine rpm is way to high
With the 4 speed top loader:
At 60 mph -3000 rpm
At 72 mph -3500 rpm
At 85 mph -4000 rpm
I took a video of my speedometer and the tach while I was driving
The rpm might be off by 100-200 rpm either way
The video is a little hard to see really clear, the car was shaking and vibrating a lot Lol
I brought my car to the shop in Dallas 2 weeks ago to have the TKO 600 with the .64 OD installed
It should be ready in 1 week
Hopefully it was the right decision
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Yes your rpm is accurate give or take 200, as I can make those numbers work within that range. Assuming the 4000 rpm 85 mph is the most accurate number and assuming the 3.54 rear gear is a fact, then I calculate a 25.3" tire.
I also calculate 1800 rpm will give you 60 mph with the .64 5th gear.
If the 3000 rpm 60 mph is correct then you have a 23.8" OD tire and 1920 RPM will give you 60 mph.