2.72 vs 3.07
2026 Loser of the Year
Joined: Sep 2013
Posts: 36,599
Likes: 7,046
From: New Or-leens Loo-z-anna
SBC350/Holley 600CFM/Headers/700R4 A.T./26" tires.......
I removed the 3.48 diff. gears and installed 2.92 diff. gears....
It's wimpy now "off the line"......but I've outgrown that....
but at 70mph/2300rpm/17 lbs. vacuum/24mpg.....I'll live with wimpy since I only need cruising rpm....and the 24mpg @ 70 mph doesn't hurt a thing either.
Now.....when doing 60mph or less--I leave the transmission in 3rd gear Lock-out (overdrive)....plenty of around town acceleration when needed.....60 mph @ 2900 rpm
Engine vacuum is a good thing to know about when it comes to a daily driver/highway driver.
I removed the 3.48 diff. gears and installed 2.92 diff. gears....
It's wimpy now "off the line"......but I've outgrown that....
but at 70mph/2300rpm/17 lbs. vacuum/24mpg.....I'll live with wimpy since I only need cruising rpm....and the 24mpg @ 70 mph doesn't hurt a thing either.
Now.....when doing 60mph or less--I leave the transmission in 3rd gear Lock-out (overdrive)....plenty of around town acceleration when needed.....60 mph @ 2900 rpm
Engine vacuum is a good thing to know about when it comes to a daily driver/highway driver.
Thread Starter
Intermediate
Joined: Aug 2006
Posts: 45
Likes: 0
From: Channahon Illinois
Wow a lot of good information. I think I will ask the guy at the ring and pinion shop what he thinks. Most likely he will not care. I do not like seeing the RPM's that high (and it is just me) 2450 Rpms @ 70 mph just sits better with me. It makes me feel the engine will last longer ?? Seeing how I just cruise I am leaning toward the 2.72 for right now.. I will be using my differential and will not have to change side yokes. All I will have done is a complete rebuild … new posit-track, seals, ring and pinion and what ever else I need.
Thanks everyone for the info….. you guys are great
Thanks everyone for the info….. you guys are great
