Technical NEED HELP WITH QC REAR END RATIOS FOR FLATHEAD W/ T5 TRANSMISSION

YOUR TRYING TO HARD ON YOUR MATH, 1st get the car done, make it drivable, rear tire size makes a difference also, you can play around with some different sized used tires and old steel rims to help you get a better idea, your never going to know how the engine runs till your done, remember ford and gm have test tracks for a reason. altitude makes a difference, and how hilly your local area is.

 

Like Krylon said.3.78. I had a 36 coupe with a 59 A flatty (4" crank ,Potvin 3/8 super cam,2 -97's)T5 and 9" rear (6.50X16's). I tried 3.90's and was to low.Then 3.78 which was perfect.The T5 had a .076 5th gear.I lived in CA high desert then and it would pull 4K mountain passes with ease.