I'm trying to decide if I should go with 4.56 or 4.88 gears and would like some input. Current details as follows. Eventually I will probably throw more motor at it though...

69 Dart
440 w/ 10.5:1 compression
906 Heads w/2.14 1.81 Valves
M1 Single Plane Intake or M1 Tunnel Ram
Hughes 246/252 555/572 Solid Cam
4 Speed
Dana 60
30/13.50/15 E.T Streets

This is a track car that will be driven on the street, however I am more concerned with track performance than how streetable it is.

Any input is appreciated. Thanks guys!

4.10

4.56

I am building a GTX with same 30 inch tall tires. I am going with 4.56 with a Dana 60 but will install a Gear Vendor OD.

My race car used to be driven on the street with 30 inch tires and 4.56 gears. Car went high 10's with a 440 and 906 heads before I rebuilt the car to go faster.

For my stuff no way would I consider 4.88 with this type of combo. Nothing to gain in my opinion..........

That cam is kind of small. I think you'll run out of rpm if you go with 4.88's. I run 4.56's with a 29" slick and trap right around 6450 rpm. I don't think that cam will rev that high and produce power. Just my

What is the 1st gear ratio of the 4 speed? I normally would run less gear with an automatic. But this isn't a automatic. My bet it might like the 4.88. I'd ask here:
https://www.facebook.com/pages/United-Manual-Transmission-Racers/350986960125
Doug

Being a stick car you will save about 7% on the RPM
due to no conv slippage... what did you calculate for
your engine rpm when you were building it

What size tire do you plan on using ? Ron

What altitude is the track you want to race it at? If below 2500 Ft (Wildhorse in Phoenix)try the 4.56, if above 2500 ft. altitude go with the 4.89 Are you going to race it in the summer there in Tuscon? If so go with the 4:89 ratio due to the severe D.A. changes in the summer in AZ

I assembled the motor for this car over 10 years ago. It is much milder than what I would build today but I'm going to run it for now and change things around further down the road. I have not made a pass in the car yet

Using the Direct Connection formula I'm thinking 4.56 is the way go. As much as I'd like to use the 4.10's I already have, I can't believe they are the right gear to use in my application. At least not for the goals I have with the car.

I have seen E.T. gains in my low compression GTX build each time I've put in a lower gear from 4.30's to 4.56 to 4.88's FWIW.

Thoughts on the D.C. formula?

4.56, unless you're running 1/8th mile you will be out of steam before you trap.

I'm running 4 speed 4.56 with 29.5 tires on the street, its great.

4:88 but we run 1/8 mile down here. 31 inch tire, 6000 at the stripe.

I ran the 30 in et streets and my trap speed was 133 and 9.95 on the et traping at 6800 iirc.

if he has a 23 spline 4 spd 1st gear is like 267 I think 18 spline is 268 can't remember. But op said he wants to run more track time than street. If he is running 1/8th mile only, he will be banging alot of gear quick, but he could use a better cam or retard it 2 degrees. My vote would be 456 or even 488's. Since he has the 410's now,I'd try them first, that is what T&T is about. But leave the cam straight up.

I run 513 this time out with a 2 spd myself. 1/8th mile only. 456 wasnt even close with my combo. but my engine builds big power after 6k.

You will get lots of opinions here. With certain combo's from certain people.You will like the M1 tunnel ram. It does make good power on a 440. If you are looking for 1/2 tenths stepping up will help.Just remember that you have to make it hook up and 4 speeds are hard on parts.