I have a 327 dropped into my 85 firebird. I got the richmond 6 speed with 3.27 1st and .76 6th. Richmond recommends a rear of 2.73 to 3.23 What do you guys think about these ratio's or should I ignore their rcommendations and go with something closer to 3.45's I know they recommend this because of the 1st gear for better gas milage ... which I definatly need. But I don't want to lose to much speed. Will I get plenty of accelleration with 2.77? With 3.27's or do I really need 3.45's? What do you guys think? BTW these are all with posi's.

 

well with a .76 6th gear you will be ok if you stay in the 3.42 or 3.45 range. If you do alot of interstate driving going any higher you are going to run fairly hi r's. I wouldnt go any higher than a 3.73 for the street. Kevin

 

Thanks

 

i'm getting ready to drop a 327 and a new 700r into mine and i think that next summer i'm gonna redo a rear end and go with 3.23's

 

Hey you will be happy with the 327!! Its a great motor I love mine. I'm also getting 350HP 400 Ft/lbs torque from mine. Didn't go any higher since I will be having a 45 mile journey to work each way! Need to have some gas milage!! I had a 3.42 open diff. I just bought a 9 bolt to better stand up to the motor. I found out later it was a 2.77 and I just bought a 3.27 gars and posi. I don't know of anyone who has the 3.45 who is willing to sell em or they are not broken! I think the 3.27 will be better anyways because of gas milage and I didn't want to lose that much power with the 2.77. For you car the 3.27 would be perfect with the auto though!

 

I don't think there will be much of an advantage to getting a much lower gear than they recomend. 3.27 is pretty lower and with a relatively low gear like a 3.73 you will be very traction poor and you will have to shift sooner and more frequently than you would with a comparatively higher gear. I would definately not go lower than 3.45, 3.27 is a pretty stout first gear. Have fun

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82 z28 350cid, vortec heads, comp 262h cam, Holley 600cfm carb, 2in twice pipes, MSD ignition, turbo 350 trans, 3.73 posi, manly b&m megashifter

 

Thanks for everyones help!

 

With your 3.27 first gear and 3.23s, that gives an equivalent overall first gear ratio similar to a 700R4 with 3.55s while in 1st.

And remember that a 700R4 in 1st gear with 3.23s is similar to TH350 with close to 3.70s. Also, while you are overdriven in 6th, you are not as steeply overdriven as many of todays overdrives. I say 3.23s would be the perfect gears for you.

 

Thats sounds great looks like I will be swapping in the 3.27 gears and posi for the 2.77 in the 9 bolt I have sitting in the garage as soon as I get the chance. I didn't know that about the TH350 or 700R4. Thanks