View Single Post
  #9  
Old September 26th, 2017, 06:16 PM
1965GMCK1502 1965GMCK1502 is offline
Member
 
Join Date: Sep 2017
Location: Monroe, NJ
Truck: 1965 GMC K 1502
Posts: 60
Rep Power: 58
1965GMCK1502 is on a distinguished road
Default Re: Topping out at 55 mph?

Quote:
Originally Posted by Ed Snyder View Post
You ID your truck as a 1000 which is a half ton. If you indeed have a half ton, the available rear end ratios were 3.08, 3.54, and 3.92. If you top out at 55 MPG, you may have the 3.92 ratio. Available ratios for 3/4 ton trucks were 4.10 and 4.56.

Fitting the tallest tires you can will help. Changing your rear end ratio will help even more. Installing an overdrive would most likely be more work and more money.
Continuing to try and educate myself, and so very thankful for this board!
My current set-up is 1965 305v6 with SM420, K1500 3/4 ton, Stromberg, Dana 60 rear (not sure if 4.1 or 4.56)
33" tires
I'm topping out at 50-52 mph and feel like I'm pushing pretty hard.
Can anyone provide info on max RPM?
Did the calculations and looks like with a 4.1, I'd be at about 2300 rpm for 53 mph....can that be right? 4.56 would get me over 2500 rpm for similar speed. Not looking to cruise up there, just trying to learn.
Maybe next mod should be a tach!
Thanks in advance.
Reply With Quote