Anyone running 3:42's

[super72bb]

Interested in some feedback...

Time has come to freshen up the rear end, I am thinking of 3:42 gears. I'm wondering if that it would be good for an "around town ratio". I have a 402 and a T400 tranny 255/60 15's. My highway miles are going to be very few and far between. So it will be just for around the city

What do you suggest?

[smitty62]

Personally I think a 3:42 is the best all 'round ratio for the street without O/D--3:07 a little too high and 3:73 'way too low @ 70 mph--------------or is it the other way around?

[boraxman]

Ive got 3.42s but havent driven my truck enough to say. i was stuck between either 3.73 or 3.42. Ive run 3.73 in a Camaro I once had and theyre pretty low for the freeway.

[Bill72BB]

I'm running 3.54's in a dana 60 with a BB , with 32 1/2 " tires great all around gears can cruise on the freeway no problem . If you are only going to use it around town you might like 4.10 for the stop light to stop light acceleration.JMO

[WRMZ71]

Super I put those in my rearend. actually I think there 3:40's cause the numbers on the ring and pinion and you divide em and you get 3:40. Anyway I had 3:73's and I drive from NC to nebraska occasionally so I wanted to drop the engine rpm a little bit out on the interstate. I got the exact same tires you do. As far as cruising around town you don't notice much of a difference between the gears its when you get out on the highway hauling balls is when you notice the difference as it brought down my rpm's at 75 mph about 500RPM or so.

[williars]

3.42 and 3.55 are my gears of choice. They provide good acceleration, and the big block will like the RPM range. My 402 3 speed eats gas around town with the 3.42, but feels right at home and gets around 12 MPG on the highway.

[boraxman]

Hey Williars, welcome to the board. Lets see a pic of your truck!

[Palf70Step]

I have 3:42 on my 96 and they are great for pulling and umph with the 350. Since I have the OD tranny it is also good on the road (bout 18-19).

[williars]

Here is my 71 SWB 402

[williars]

My 83 Chevy

[smitty62]

All these trucks eat gas and you can't fix it with just the rear end. They weren't built with mileage in mind.

[flip66]

I have a 396 with 3:42 they work great. Have a frinde with 3:73 and he hates them for Hiway driving.

[Faster_than_you]

actually son, I built my 454 to have a range of 15-17 mpg on the highway. I have stock 3.73 gearing, with a quadrajet carb I get about 16 mpg. and 375 ponies at my pleasure to burn. but with my edelbrock carb I have, I will be lucky to get around 9, funny just a carb change can change all that. i also am thinking about a supercharger, have experienced were mileage will increase dramatically with one of these hotties hooked in. so to end this reply, no in fact these trucks were built with mpg in mind.

[smitty62]

"To end this reply"???? Did I miss something?? When were you elected moderator--with your first posting? 15-17 mpg with a big block & 3:73 gears?? Anyone that believes that no doubt owns the Brooklyn bridge as well. Do you actually know how to figure gas mileage? You don't do it with one tank of gas--it takes at least 3 to do it accurately plus these odometers are notorious for being inaccurate-especially when you vary away from the stock tire diameter. These trucks are as areodynamic as a billboard being pushed down the interstate and fiddling with carburetors or rear gears aren't going to help much. If you can really accomplish what you say Detroit would love to have your engineering skills.

[super72bb]

To tell you the truth I never asked about the gear ratio's in this post because of gas consumption. I could really care less about it! I am building a show/summer cruiser and I want a good ratio for around town and on cruise nights. So I think the 3:42's sound pretty good for all around fun.

Thanks for the replies.

Curt