I was looking at some past posts, and I came across one talking about a s/b 400 and how since it has more low end torque, there is not need to run at higher rpms when driving. I am dropping in a SB 400 into my pickup, so just wanted to here what you guys think about my rpm range. There is a website [www.smokemup.com] that can calculate the speed for rpm range by putting in your rearend ratio, tire size, and tranny. I am running a 3.4:1 rearend, 25-26" tires (don't know yet), and a TH350 tranny. If I ran 25" tires, here is what it would look like RPMS-----------1st---------2nd-----------3rd gear speeds. 1000-----------8------------14-----------21 1500-----------13-----------21-----------32 2000-----------17-----------28-----------42 2500-----------21-----------35-----------53 3000-----------25-----------42-----------64 3500-----------29-----------49-----------74 4000-----------34-----------56-----------85 So at 3000 Rs, I would be going 64 mph. From looking at the info...is this going to be a good setup for the s/b 400? The only thing I can really change with is the tire size (I haven't bought them yet). If you could give me some input...that would be great. Thanks. Check out that site...its pretty cool.
That seems about right. I have had chevy trucks with 350's and 454's, and your sb400 rpm range looks safe, and about right. If you plan on running it at 75+ MPH regularly, you might want to get your RPM's down a few hundred...otherwise your fine. Your freeway passing-power at 3K RPM with your 400 should be awesome good luck! -Paul
