Ballpark Gear Ratio

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SpeedThrills

SpeedThrills

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My Duster clone is roughly 3000# w/ me. I haven't had it on a scale yet. 'Glass bumpers alum bumper brackets, glass hood and fenders. Minimal interior (2 Corbeau buckets), no heater, Weld Pro Stars.
It has a 360 w/ ported 915's, 770 vac sec carb, Torker II intake, 292 purple cam, 11.25:1 comp, 1 3/4 headers.3200-3500ish convertor, 26" tall tires and 4.10 gears. (380ish hp?)
I recently got it running, and the rear howls big time.
This driveline came out of a totaled D150, so I have no practical experience with it.
If I need to replace the ring & pinion, what would be close to the "right" ratio?
I tried the Wallace calculator, but I have too many unknowns.
 
We run 3:91 in all our small blocks

Street/Strip cars that run high 10's @120

If your car is more like 12.o @110 then 410 430
wounde be optimal
 
Thanks John. I’m surprised. I know you run S/SS, which I always thought ran “tongue out”. I was figuring 4.56 or even 4.88.
 
If you go through the traps at 6500 RPM with a 4.30 gear and a 26" tire you would be doing about 117MPH, which for a 375 HP engine with a 3000 pound car sounds about right. I would say that 4.30 is about as much as you would want to go. With 4.56 speed at 6500 goes to 110MPH and 4.88 would be 103mph.
 
RIGHT as far as what? 4.10 is right for a lot of people. What are your plans?
 
HSDemon said:
If you go through the traps at 6500 RPM with a 4.30 gear and a 26" tire you would be doing about 117MPH, which for a 375 HP engine with a 3000 pound car sounds about right. I would say that 4.30 is about as much as you would want to go. With 4.56 speed at 6500 goes to 110MPH and 4.88 would be 103mph.
Click to expand...
The first word, "If", is the problem. I know I'll be guessing, but I'm trying to take the best guess I can.

RustyRatRod said:
RIGHT as far as what? 4.10 is right for a lot of people. What are your plans?
Click to expand...
1/4 mile drag racing.
 
I would go back with new 4.10s in that case.
 
SpeedThrills said:
Thanks John. I’m surprised. I know you run S/SS, which I always thought ran “tongue out”. I was figuring 4.56 or even 4.88.
Click to expand...

Even in our 7000 RPMJ+ Stocker = where most guys are in the 5 series we run 4:56.
Torque is what makes our cars run fast the way we set them up. More gear
makes more noise but not quicker ET for us.
My kids are not going to like me revealing This info!!

If anyone was at Mopar at the Strip (LVMS) = My son's 68 360 Valiant
(10 Sec. thru mufflers) won the "Street Legal" Eliminator with 3:91 so
I practice what I say.
 
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GTX JOHN said:
Even in our 7000 RPMJ+ Stocker = where most guys are in the 5 series we run 4:56.
Torque is what makes our cars run fast the way we set them up. More gear
makes more noise but not quicker ET for us.
My kids are not going to like me revealing This info!!
Click to expand...
I won't tell. :D In the 70's. a friend ran 4.10's (factory installed), in a 69 six pack Road Runner Stocker. In the 90's, he and I tried 488's in a similar car, because that's what everyone was doing. It ran the same as the 69.

33IMP said:
I'm sorry, I don't know what came out of a D150.
8 3/4? Dana 60? 9 1/4?
Click to expand...
I should've mentioned that it was a Pro Street truck, and had a 9" Ford.

I'm leaning towards 4.30's after reading all of this, because I plan on using a taller tire in the future.
 
SpeedThrills said:
My Duster clone is roughly 3000# w/ me. I haven't had it on a scale yet. 'Glass bumpers alum bumper brackets, glass hood and fenders. Minimal interior (2 Corbeau buckets), no heater, Weld Pro Stars.
It has a 360 w/ ported 915's, 770 vac sec carb, Torker II intake, 292 purple cam, 11.25:1 comp, 1 3/4 headers.3200-3500ish convertor, 26" tall tires and 4.10 gears. (380ish hp?)
I recently got it running, and the rear howls big time.
This driveline came out of a totaled D150, so I have no practical experience with it.
If I need to replace the ring & pinion, what would be close to the "right" ratio?
I tried the Wallace calculator, but I have too many unknowns.
Click to expand...

My one duster with a stock stroke 360 went thru the traps at 6800 with 28" tires and 4.56 gears. Later changed to a 30" slick and the rpm dropped to 6300. This was with a 8" 5000 stall convertor in a 727. Your probably going to want a 3.91/4.10 ratio with that short 26" tire depending on how many rpms you want to turn.
 
SpeedThrills said:
Thanks John. I’m surprised. I know you run S/SS, which I always thought ran “tongue out”. I was figuring 4.56 or even 4.88.
Click to expand...

me too, or even 5.13 gears.
Never heard of a small block stock/ super stock guy running anything remotely close to a 3.91 gears in a class car
 
I used to run a very similar combo on a 71 Duster 340 I had in the early 90's, 340 .040 over, ported T/A heads with Manley SS valves, 292 purple shaft cam, M1 single plane intake, 750 Barry Grant Carb (I think those flowed like 900/950 CFM), 10.5:1 compression, 1 3/4" headers, 727 with a 3500 Turbo Action converter, reverse valve body. Complete car with full bucket seat interior and console, non-A/C car, with PS and PB. I ran 4.30 gears but at the track I used a 28x9 slicks. Only took it twice to the drag strip, but the second time it ran 12.6 at 116 MPH. With a 26" tire I would say 4.10 is probably your best bet. This was a street car and it was a pain to run it with 4.30 gears on the street and the loose converter.
 
I run the same 292 cam in 360 dart sport. It's pretty happy with 3.91's! Also a 9.5" FTI 3400-3600 stall converter helps.
 
GTX JOHN said:
Even in our 7000 RPMJ+ Stocker = where most guys are in the 5 series we run 4:56.
Torque is what makes our cars run fast the way we set them up. More gear
makes more noise but not quicker ET for us.
My kids are not going to like me revealing This info!!

If anyone was at Mopar at the Strip (LVMS) = My son's 68 360 Valiant
(10 Sec. thru mufflers) won the "Street Legal" Eliminator with 3:91 so
I practice what I say.
Click to expand...
B3422w5 said:
me too, or even 5.13 gears.
Never heard of a small block stock/ super stock guy running anything remotely close to a 3.91 gears in a class car
Click to expand...

I run 3:91 in my Street/Strip Bracket cars. They run with Air Cleaner on thru the muffler and
do not see over 6,300 RPM Even @ 120+ .MPH. The Stock Eliminator cars shift @ 6,800 and
go thru the lights @ close to 7000. As above = I run 4:56 @ Sea Level/ 4:88 @ 2000 to 3000 Ft/
5:13 @ 5000 plus elevations.

At Nationals in Denver a few years ago my margin of victory in class
finals was .0001 at finish line against another 340 Stocker. I have tested
this stuff for around 60 years and if I was faster with more gear I would
run it. I had 4:88 gears and he ran 5:38 gears (Denver is 5800 Ft.) He
was a couple hundred faster 60 ft put I was 2 MPH faster at finish. We both
put up .01 reaction and that made for a fun race.

I did not represent that I ran a 3:91 in a Stock or Superstock car.
 
Last edited:
GTX JOHN said:
I run 3:91 in my Street/Strip Bracket cars. They run with Air Cleaner on thru the muffler and
do not see over 6,300 RPM Even @ 120+ .MPH. The Stock Eliminator cars shift @ 6,800 and
go thru the lights @ close to 7000. As above = I run 4:56 @ Sea Level/ 4:88 @ 2000 to 3000 Ft/
5:13 @ 5000 plus elevations.

At Nationals in Denver a few years ago my margin of victory in class
finals was .0001 at finish line against another 340 Stocker. I have tested
this stuff for around 60 years and if I was faster with more gear I would
run it. I had 4:88 gears and he ran 5:38 gears (Denver is 5800 Ft.) He
was a couple hundred faster 60 ft put I was 2 MPH faster at finish. We both
put up .01 reaction and that made for a fun race.

I did not represent that I ran a 3:91 in a Stock or Superstock car.
Click to expand...


Sorry….saw your first line that said……” we run 3.91’s in all our smallblocks”
My bad. Yea, street strip car 3.91 is a good gear.
 
GTX JOHN said:
I run 3:91 in my Street/Strip Bracket cars. They run with Air Cleaner on thru the muffler and
do not see over 6,300 RPM Even @ 120+ .MPH. The Stock Eliminator cars shift @ 6,800 and
go thru the lights @ close to 7000. As above = I run 4:56 @ Sea Level/ 4:88 @ 2000 to 3000 Ft/
5:13 @ 5000 plus elevations.

At Nationals in Denver a few years ago my margin of victory in class
finals was .0001 at finish line against another 340 Stocker. I have tested
this stuff for around 60 years and if I was faster with more gear I would
run it. I had 4:88 gears and he ran 5:38 gears (Denver is 5800 Ft.) He
was a couple hundred faster 60 ft put I was 2 MPH faster at finish. We both
put up .01 reaction and that made for a fun race.

I did not represent that I ran a 3:91 in a Stock or Superstock car.
Click to expand...
What size tire do you run?
 
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