currently running a 373 gear ratio with a 350 turbo 455 engine and a 27 inch tire and im looking for a good gear that will cruise comfortably at 65 mph but still have the low end grunt. going to a 284-88h cam this weekend also. ive tossed around the idea off a 200r4 but thats not in my budget at the moment and feel the previous 2.56 gears are a bit too high any suggestions?
Your thread title almost answers your own question - I've got cars with each gear and I like them all. My Pontiac has 3.08's, it's a terrific high speed cruiser, 80-90 mph all day long and the engine doesnt mind, but still has a bit of grunt compared to a 2 series gear. My 65 had 3.23's and was still good for distance.. would drive it to the track and race all day, pulling 60 ft's in the 2.10 range. My personal favorites are 3.42's - GM used them all over the performance range for good reason, but you can still get the car from state to state. My 73 has them and with a 235-15 tire I barely notice the revs on the highway. I also put some in my 65 and with a 14 inch tire they get kind of buzzy, but also put my 60 fts in the 2.0 range. My advice is 3.23s or 3.42s....
to me 3.08 is the ultimate compromise gear for behind a 3 speed trans. I run them in my 79 trans am. great for a driver, drive it anywhere. 3.23 is just that little bit sportier, I personally wouldn't like to go any further with a 3 spd trans, especially if hiway driven. you cant go wrong with either ratio behind a 3 speed trans. I am running 3.23s with 255 tires behind the th350 In my 72 skylark 455, and it drives great around town and runs low 13s at the strip right now. Hiway revs are around 3 grand at speed.
A 3:23 or 3:42 would be fine for non-AC .If your car has AC,then run a 3:08 or 3:23. If you get the rpms up too high,the AC clutch disengages,so you would not have AC on the highway.
I'm running 3.42 with a overdrive trans. I was going to move up to 3.73 but after reading Brian's post maybe I should stick with 3.42. In So. Cal. AC is almost required. can high rpm damage the compressor clutch ?
Your good, the OP said that the 200R4 ISN'T in the budget right now. With you already having O/D, if its a 200R4 with a .67 4th gear your final drive ratio will be 3.42 x .67 = 2.2914:1 with a 3.73 would still be 2.4991:1 still doesn't = that big of a jump in RPM. GL Derek
What tire diameter is on your 73? A shorter tire,like a 26" will raise the rpms versus a taller tire. Good to hear that you can run 3:42's with AC in the highway. I don't have anything with AC,and I run steeper gears. Heck,I don't have anything with power brakes or power steering either. I like it simple. For the guys running overdrives,I generally build a 3:42 or 3:73 for the big block guys,and 3:90 or 4:10 for the small block guys.Dont take it as gospel though.
The Stage1 A/C compressor came with a bigger A/C pulley. I believe it was 5 3/4" in diameter. The purpose being to slow the compressor down so it didn't reach "belt slinging" speed:laugh:
3.08s with 225 70 14s or 245 60 15s 3.23s with 255 60 15s 3.42s with 275 60 15s This is what I recommend from my experience when looking to compromise between performance and drivability using the T350 or T400 3 speed transmission and a big block. Go up one gear with a small block.
I run 3.42's on my 71 350 GS w/T350 245/60/15's 275/50/15 MT DR's on 8" Buick chrome rims when going to the track 26" or 26.5" overall dia. I wouldn't go any lower in gear than 3.42 without an overdrive trans.
I can also attest to the 3.08's. With 14 inch wheels and lower profile 245-60 tires it does not take too long to get into the power back and car will run high 12's all day. The only thing is I'd love to improve on my 60 foot times and have a set of 3.55s but I am hesitant to use them because cruising at 60-70 is absolutely perfect tone-wise and throttle response wise. Still has sick passing power at 70mph. But again, I sacrifice a little at the bottom end (although a posi probably would help that too.)
