I Bought an 87 cutlass, I have a 425 I am putting in it, the motor has a healthy cam, I am running an AED 750 double pumper on it, and headers, I have a 200R4, I am also going to run, that I plan on having CK transmissions help me out with. While at the GM nationals I purchased a 8.5 GN rear, the rear has a Eaton posi unit in it, but currently it has 4:56 gears, these are crazy and need to go. I am thinking about going with the original 3:42 gears. I plan on driving this car, keeping the A/C working, but It will be seeing some track time. 🙂 Based on what I am running here, I would love to get some feed back, or suggestions as to what would be a nice gear ratio for what I am up to.
Gear selection, advice needed!
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being that you will have OD if it were me i would entertain 3.73 a the least and most likely 3.90 gears. I remember looking at that rear at the GM nationals. Hope you got it for a song. Healthy cams generally like a lower gear. I run a 3.42 behind my muncie but with my cam the car really wants a little more. however the 1:1 final drive ratio limits me if i plan on highway driving.
I ran some numbers and with the 2004R your effective ratio in OD will be 2.49 with the 3.73 and 2.29 with the 3.42s.
Figuring a 26” tall tire at 75 MPH the engine will be turning 2413 RPM with the 3.73s or 2220 RPM with the 3.42s. Depending on how healthy the cam is the engine make actually like the extra couple of hundred RPM going down the highway.
Figuring a 26” tall tire at 75 MPH the engine will be turning 2413 RPM with the 3.73s or 2220 RPM with the 3.42s. Depending on how healthy the cam is the engine make actually like the extra couple of hundred RPM going down the highway.
Thanks, Mike, that is what I needed to know! I think I will go with a 3:73 then. I plan on driving the car, but it is not going to be my family traveling car. lol I also think it will be fun with 3:73 gears in it!! 🙂
3.73's will be fun with that o/d,I have a 700r4 with 4.10 gears and I love it , not too high on the expressway either. You will be more then satisfied with ckperformance as well for your transmission needs !!
Thanks! I have decided on the 3:73 gears! A friend is running 4:11's and a 700R4, I drove it, it's great!!! I am looking forward to doing mine, Did you have CK do your transmission?
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