N.o.s or 4.10 gears?

I bracket race a 1972 duster.It has a 318.It runs the 1/4 mile in the 15.6 range.I would like opinions on which modification to do.I can only afford to do one or the other.So do I do a 100 shot of N.O.S or a gear change from 3.55 to 4.10.

Which axle do you have, 8-1/4"? Don't invest in it.
Nitrous will have far greater results.

I have a 8 3/4.

Shoot it,

you will be amazed at what a little .052 nitrous jet will do.
Probably get 3-5 passes out of a bottle also.

Gears are a one time expense and install deal. Nitrous needs to have the bottle(s) refilled constantly. What is N2O now? $5/lb?

Is this car street driven? Saving your pennies for a decent 360 or similar upgrade may be the best route.

Getting weight out of the car is the easiest, cheapest way to make it go faster.

How about lever C. Buy a running 360 and upgrade the cam slightly.

What is your objective?

I can tell you from experience that trying to bracket race with spray is a lot of work. Can it be consistent? Yes, but you have to keep really good control of bottle temp and pressure. Not easy to do on a hot day, especially if you get stuck in the lanes by an oil down or such. If it's cold out that brings on another bunch of fun.

Going from 3.55 to 4.10 will not pick you up as much as you'd think.

Another vote for a 360.

I sold a 4 speed Duster to a friend, it had 3.55 posi third member in it,we swap in a posi 4.89 gears third member, it made that car FEEL a lot faster but it didn't make much ET or MPH difference in the 1/4 mile It picked up from 14.5s to 14.20 to 14.30sET
If you want to go faster try a better converter and focus on making more power

Like has been said already, the gear change won't get you much. The 100 shot will pick it up a LOT and be a helluva lot of fun. Definitely the best bang for the buck. Bracket racing it w/ the nitrous may or may not be for you.

But it cost money EVERY time you push the button. Not needed to pick up how much ET he would be happy with.

I understand what you're saying John, but he gave us 2 options he's looking at and he's obviously on a budget.

No2 is like a hot chic with std`s , you know it`s dangerous but you still want to hit it

All depends on how much you want to pick up from 15.6's, assuming your@say 3400lbs all in your making around 175fwhp not knowing your mph..86>87mph?. Adding a 100>125 shot could take you to 13.5's@99>100mph. It will be almost like going to 4.10's with your 3.55's with the added torque of N20 and will lower your 60's as long as you still hook and be the biggest gain you will get for minimal cost/effort over going the NA route.

what is the set up now? with a tiny bit of head work, intake, carb, headers cam you should be able to run high 13's pretty easy. I had a 69 coronet with the stock 318 2bbl, 727 stock convert, 3.23's. With the air cleaner lid flipped advanced timing and 5 gal of 110 the car ran 15.69-15.72 all day. I would think a slightly modified 318 in an a-body would run 14's w/o much issue. With the above advice you could do one mod per paycheck...

Set of cleaned up 360 or J heads, 4 bbl, intake and a little cam would pick it way up. Converter would be a big help too. Either of the two options are $400 - 500. Pretty good start on other options.

13.50

jump in with both feet and go straight to NU-BE gears : 5.38's !

The last SB 4 speed Duster I drove had 5.57 rea gears with a 3.09 first gear in the tranny using 13x30x15 inch slicks, you where real busy in that rascal the first 300 ft.
That car weighed right at 3200 Lbs. with me in it and only ran low 11.s

you would certainly get your coordination workout with that combo cab ! makes me want to take a nap just thinking about it !

That car was sold to a guy who became a friend later, I had removed the 3.55 posi from it and install a 4.89 posi third member in the car before selling it to him. I was street race car from San Bernardino that I traded a 1974 Yamaha 500 MX and fifty dollar in 1974
Long story short it ended up with a cross ram M.P. SS Hemi motor in it with a 727 and 4.89 gears in the Dana 60 the got installed after the guy I sold the car to had broke around 6 different 8 3/4 gears sets in the car with the 340 and 4 speed
We all had a lot of fun with that car and made some money with it, he won the division 7 bracket finals in it with one of my 440 M.W. bracket motors and 727 in it that we had installed to run Super Street in 1984 in it

If it doesn’t have one yet(or is a 4 speed), I’d buy a good converter.

What has been done to the car so far? 2 seconds is a big jump.

And if there's any budget left, spend it on the suspension. I think a slower car that will print time slips will statistically go more rounds than a fast car that has to chase it down.

Kevin

Nitrous

Spray it. The gear will have you wound up all the time.

Every bit of speed comes at a cost, so pay a little here and there for some juice, and when funds are low, your car won't know. The gear will always be in play.

SUM-K50062 150.00, Used intake $75, Carb $200... there's second off your et and you don't need to refill any bottles.

One thing I really like about spray.

On stock motors 100 is great, 150 is better, 200 is amazing, 250 over the moon fun,,,then,,,O no...

Then you commit to better parts, because once you feel that you're never going back.

Then there's another racer out there supporting the mopar parts factory, unless you get really smart, and abandon the brand LOL.