gear advice

[l8rg8r]

I have a 383 4spd in my 68 roadrunner the engine is stock bore 906 heads im running voodoo cam 60303lk ,comp cams double springs, sixpack intake/carbs, msd 7 ign and hooker super comps with 295 rear tires.:headbang: I have finally reached the point of this build to select my gears i have my choice of 3.23,3.91,4.10 and 4.30 all are sure grip except the 4.10 and it a spool so what should i run

 

[RustyRatRod]

4.30. The short stroke motor will love it.

 

[tpodwdog]

3:55's

 

[1970GTX]

X2, 3.55

 

[benno440]

yeh definetly 3:55, give your engine some relief on the highway

 

[Meep-Meep]

That cam should be all over the 3.91 - 4.30's. For optimum 1/4 mile I'd start with the 4.10's and most likely end up with the 4.30's. I had 4.88's in my 383 RR and it loved it. I also ran 3.55's and it was OK for street driving but didn't have the low end punch I was looking for. The gear change made a .7 second difference!

 

[hunt2elk]

I'm running 3.91's and really like them, but cruising @ 70 on the highway is not happening. They sure are fun in town though.

 

[RustyRatRod]

That cam should be all over the 3.91 - 4.30's. For optimum 1/4 mile I'd start with the 4.10's and most likely end up with the 4.30's. I had 4.88's in my 383 RR and it loved it. I also ran 3.55's and it was OK for street driving but didn't have the low end punch I was looking for. The gear change made a .7 second difference!

I tried but the grandmas came out.

 

[Hemi Rebel]

I would avoid the spool on the street. 295 what rear tires? 295 is the width. the diameter of the rim and the aspect ratio would be good to know too, but i imagine its an average size street tire. For a street car I would stick to the 55's or 91's. It would most likely run best with the 4:30's, But unless you spend more time on the track than the street, you will find the higher gears more enjoyable. JMHO

 

[RustyRatRod]

The optimum thing to do would be to run an overdrive transmission. That way you could run the 4.30 and have the best of both worlds.

 

[Sprag]

4.30. You only live once. This must be done.

 

[Sweet5ltr]

4.30 gear! Who drives a muscle car with a SIX PACK for fuel economy!?

 

[Propwash]

http://www.richmondgear.com/101032.html

 

[wingcarenvy]

I ran 3.91s in my stock Road Runner and it was great at the track very livable on the street. I wouldn't go any less than 4:10s. I run 4.56s in everything else. Play with the rpm calculator that prop posted and you will see its only a few hundred rpm difference on the highway, and whats 300 rpm when the motor is already turning 3000.

 

[rev.ronnie]

I put 3.73s in my Charger instead of the 4.10 it came with . Running a 275 60 r15 BFG radial T/A it's all the steeper I need. I really wish I would have gone with a 3.55 in hindsight, because I do a bit of highway driving between houses and shows.

With 545# pounds of torque, it really pulls like a freight train on the highway without kicking it down a gear though. When the outer carbs open, it feels like it kicked into passing gear.

that said, a 383 is going to be a little more high strung, so you may really like the 3.90-4.30 range depending on your tire height and how much highway driving you will be doing.

 

[shag766]

3:91's or the 4:10's
above 4:10's you are restricting your self to local mostly driving. below 3:91's you are not utilizing that motor

2 cents

 

[HT413]

I run 3:91s and 29" tires and its very livable on the street. The taller tires help for sure. I cruise all the time at or near 65 no prob (in the ballpark of 3000 rpm .

 

[benno440]

got nothing to do with fuel economy, unless hes at the track every weekend and never cruises the highway.
the lower gears are to get soem better life out of your engine, i would not be comfortable with my $25000 motor revving off its tits every where i go, would you?

 

[Meep-Meep]

True, but he has a pretty hefty cam and that needs the deeper gears to keep the power band where it should be. If lower RPM cruising is the goal then a more appropriate cam should be chosen.

 

[rev.ronnie]

For all around driving comfort, gear it to match the most common cruising rpm with the engine RPM in the lowest point of its powerband. If you want to cruise at 70 and your engine is happy at 2800, gear it that way, whatever it is. If you like boulevard cruising at 35-45 and want stoplight to stoplight fun, gear it that way. you are going to have to make a concession somewhere.

Hindsight, I wish I had 2.73 gears in my Charger or an overdrive. I don't drive it much because I'm sick of hearing it spin RPM and go nowhere. It's in 3rd gear by the time I am across an intersection from a stop. But, then, I have a race car so I don't drive the Charger to go burn rubber and street race.