Need help w/gear and slick size on a 402 Duster

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Blue Grey Duster

Blue Grey Duster

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Putting together a 70 Duster, it was a 340 car. 402 Magnum Stroker Crate Motor, Dist. and Orange box came with it. Have S.S. Springs, stock 727 w/ 2800 TCI 11" Breakaway , TTI step Header w/ 2 1/2 " full exh. ,750 3310 Holley . Can always up grade the carb., convertor, and go to 3" Exh.. Conservative set up, but I like what I have, just starting out. Still need things like a shift light and rev. limiter. Only had it out once and got rained out. Got one good run in, but it was in Drive so it shifted early. I plan on shifting @5500. Since then, I've added frame connectors, a driveshaft loop, and got rid of the power steering. W/stock 25" tires and 3.23 gears w/ sure grip---rolled and stomped it. 13.232 at 106. Don't know what to do about tire size and a gear. Will I need a tall tire with a stroker? I don't have much experience with Drag Racing, and I'm asking You Guys to fill in the Blanks. I'd like to have a respectable MOPAR. Any and all suggestions would be appreciated. Thank you for the A-Bodies Web sight. :cheers:
 
I will assume you have a big bolt pattern axel, but my suggestion if it is a street/strip car would be to go with a 3.55 gear and a 26" tall tire, for your combo it would do really well with a 235/60/15 BFG drag radial and that ratio, should be able to dead hook on grease. I used to run 11.50's all day long with my 408 when it was in Demon with 26" BFG's and 3.91 gear, but I had a little more motor than you. My thought would be that the converter is probably a little tight for your motor to go 106 mph. A 3500 stall 10" would be a good fit IMO. Lots of Big Bolt pattern wheels available for different backspacing but IIRC a 15x8 wheel with 4.5 inches of backspacing will fit without having the leaf springs moved in.
 
I'd go with atleast a 3500-3800 stall converter(if you want the best out there give Ultimate a call) 3.91-4.10 gear and either a m/t 275/60 15 drag radial or 28x9 slick..my 416 ran consistent 11.0's with the above combo..by the way bfg's drag radiald are USELESS...........
 
I'm for the largest diameter you can fit in it. I believe without trimming the wheel well that's 28". trap speeds areound 110 you're looking at keeping the rpms down near 5500 at the stripe. So I'd go 3.91s. If it were me, I'd plan to replace teh convertor with a 9.5" unit that stalls around 3400 and test your shift points. I think you may find that it wants to be shifted lower than 5500. At least until the carb is updated as it will be hitting an wall around 5500. Go with something at least 850 dry flowed CFM.
 
Thanks for all the info guys, alot of good suggestions. I'll hang on to all your input. I appreciate all of it. Can't wait to get this 402 stroker rolling.
I've been looking at the chassis book and it looks like I should be shooting for a 12.05 E. T. if I do things right and the advertised H.P. rating is accurate. Taking 17% off the engine I get 361H.P. at the wheels, w /3200 lb ( estimate right now can always make it there) Duster, End up with a .113 P/W ratio =112mph Qtr., Auto,=12.05 E.T. using chart 9 and 10 on page 355-356, w/ Good Chassis.
Looking at the Tire Diameter formulas at 112mph I get: 27" w/ 3.91 @5500, 28" w/ 3.91 @5300, 28.4" w/ 4.10 @ 5500, 27.4" w/ 4.10 @ 5700, 28.7" w/ 4.30 @ 5700. I hope I'm doing this right? Correct Me If I'm Wrong- Here, I'm sure experience is another thing compared to these formulas.
 
this may or may not help but i have a 493.

28" tire ran 6400 in the lights.

29 runs 6200. at 125 mph

with a 4:10 dana. in a dart.
 
Thanks dart496, that's what It's all about. Racers sharing good information. I'm sure other Guys are being helped also.
 
Thanks Tracy and Fishy68, That is so neat. Takes all the work out of doing formulas. I just click auto, Drive, check the gear, run the throttle to set the mph to 112, adjust the tire diameter to get @5500, and there's my combination. Just change gears for more. That is so nice. Helps give you the big picture.:toothy10:
Looks like it's between a 3.91 and a 4.10 . A 3.55 won't even work. Not sure about the tire size and I've got to consider if I get a little faster. I need to make a complete pass with some slicks and go from there.
I made a graft of the rpm's, to compare the different tire sizes. :burnout:
 
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