Tires / diff ratio advise

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A Body 440 WHY NOT

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I am working on my 69 dart that will have a 440 /727 / 8 3/4 in it . 10-1 cr, alum heads , The stall is 2800 and the cam builds at roughly 3000 to 6000 rpms. I can look up the Isky specs if needed. My question for advise is should I go 355 ratio and 15" tires ( taller 27/28" dia ) , or 323 ratio and 14" tires ( not as tall. 25" dia). I need a ring and pinion either way and rear tires and rims too. It's a project
Thanks for the advise !
I should include that it's a street car / fun car. Not a daily or a drag car .
 
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the cam builds at roughly 3000 to 6000 rpms.

should I go 355 ratio and 15" tires ( taller 27/28" dia ) , or 323 ratio and 14" tires ( not as tall. 25" dia).

Did you dyno the engine? How do you know where it builds power? If it's based off the powerband on the cam card you might as well throw it in the garbage, most often TOTALLY inaccurate.


3.55 and 15" wheels with 27 - 28" tires is a no brainer.
 
Did you dyno the engine? How do you know where it builds power? If it's based off the powerband on the cam card you might as well throw it in the garbage, most often TOTALLY inaccurate.


3.55 and 15" wheels with 27 - 28" tires is a no brainer.

The engine has not been on a dyno. Just using the cam as a guide.
I do like the 355s and 15" wheels. Just figured I'd ask and see if there was something else to consider. I am going to order the gear set soon. US gear is what I am leaning towards. Thanks
 
The tallest widest tires and the smallest rear gear, so you never have to manually shift.
Say ........... 2.94s and 28s;
65=2290 at zero slip. and
60 in first is 5450 at 5% slip, .................... assuming the tires aren't still spinning.

EDIT;
3.23s would be ~10% more
3.55 would be ~10% more over 3.23s
After this the ratios are spaced about plus 5% per swap, to 4.56s
>>You can buy/install a tool that will measure your acceleration over time, and if it knows your vehicle weight, then it can spit out a power curve. My favorite is the G-tech ProSS. You can use that curve to help you select the appropriate for you, stall and rear gear.
> If you have traction problems, IMO, gears are no big thing, cuz 2.94s will get you to 65 with no shift, but you only go thru the powerpeak one time. Whereas 4.56s would let you go thru it twice and end at 65=5600. Theoretically, the 4.56s would get you a lower ET ........ if you could figure out a way to make it hook; otherwise, at WOT, the power just goes to tiresmoke. And if you can't go WOT without tiresmoke.......... then you couldda just started with a smaller engine.
Any other rear gear between 2.94 and 4.56 SHOULD get you an inbetween ET....... if you can make it hook.
Us small block guys don't usually have this kind of problem/option,lol.This is the principal reason us small block guys can often/usually pound you BB-boys in low-speed contests, and the principal reason 318boys can pester traction-challenged 360boys.
But you know; if you have a choice between zero to 60 in 5.5 seconds with no tiresmoke, or 5.5 with nothing but tiresmoke, I would chose the latter,lol. Just make sure it goes where you point it, and that the brakes work real good if it don't..
 
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The engine has not been on a dyno. Just using the cam as a guide.

Very inaccurate. Forget all that.

IN your case what I would do is just figure what RPM you'd like it to be at when at cruise speed. I.e. My car at 60mph turns 2500RPM with 28" tall tires, 4.56 gears and the overdrive on.
 
I run a 3.55,a 3000 stall convertor, and 27 inch tires on my dart. Its a pretty good setup with the 383/727/ 8 3/4.
 
Very inaccurate. Forget all that.

IN your case what I would do is just figure what RPM you'd like it to be at when at cruise speed. I.e. My car at 60mph turns 2500RPM with 28" tall tires, 4.56 gears and the overdrive on.

Overdrive is nice !
I won't have OD. But would be cool ........
 
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