Hey boys and girls long time listener first time caller. I got my 51 Chevy it has a 250 straight 6 with a 3 on the tree. The drive line is all 1974 Nova. As far as I know if you bought a 6 cyclinder nova with a manual it came with a 4:11 gear in it. My question is what gear should I run since its screaming pretty good at 60-70 mph. 3:73-3:55?? I dont want to put alot of strain on the clutch and stuff. Thanks Pribbz
'74 250 Nova came standard with 3.08 gears. Option codes for 1974 were-- JA - 2.73 open JB - 3.08 open JC - 3.42 open JM - 2.73 posi JN - 3.08 posi JP - 3.42 posi
how will it be driven, are you cruising? looking for fuel mileage? hills? 3.36 wouldn't be too high for day to day type driving.
Yep your right it is a 3:08. I must have gotten a bad source. Well just looking for a better all around gear. Its fine in town it just screams at highway speeds. I dont have a tach but id say its above 3grand. I thought about a 5 speed but I kinda wanna keep the 3 on the tree.
Ok so according to the calculator if I have a 4:11 gear in my car Im taching like 3700 rpm at 70 mph which by the seat of my pants seems right. If I put a 3:08 which is factory for a 74 nova thatll put me at 2700 rpm at 70mph. I guess I either need to take it apart and count the teeth or rig up a tach and go for a ride. Thanks for the help.
2.73 or 2.54 might get you a little bit, but any lower than that and you may have trouble getting the car rolling off the line. Also, you are probably going to spend a small fortune on a 2.73 or 2.54 ring and pinion set since they will be aftermarket only. While swapping transmission may not be an appealing solution, it probably is a better solution since the top end will have overdrive to solve your problem. Or, if you want to spend a LOT of money, look at an aftermarket OD unit for your existing transmission.
Those option codes I posted above should be stamped on the pumpkin. That doesn't guarantee they have never been swapped out, but it might save you popping the lid.
Yes, I read (and responded to) that fact... I even posted factory codes for the rearend options. Since those ratios didn't come in that rear from GM, the OP would have to buy from the aftermarket, rather than snagging a cheap junkyard set... hence my statement about cost. I didn't claim they couldn't be had.
You can get a pretty close estimate of your ratio without tearing anything apart. This video explains it pretty well: http://www.youtube.com/watch?v=i_Enyf67KTs Read the comments if you have an open diff.
Yeah, I was taught to do it that way 40 some years ago, so I'm always surprised when people still go to more convoluted methods. You don't even need tape - just chalk the driveshaft and tire.
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