“Best” all around axle ratio: ~450hp w/ A904?

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MRGTX

MRGTX

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Looking for opinions/experience before I take a flying leap at this and live to regret it.

Relevant info- 408 stroker, upgraded A904 (with stock 1973 ratios), 2600 rpm converter, 26” tall tires. 8.75” axle with 4.10 ratio. Currently, 40mph comes at just about 2k rpm.

I love cars that can rev high and be happy in the high side of the tach but not when it’s pointless to do so. This motor seems to breathe well enough where it’s not gasping at 5k but it makes about the same power at 3500 so it feels like I’m just burning extra gas and wearing the engine out faster than necessary.

I’m not trying to absolutely max out quarter mile times and I’m not trying to maximize fuel economy. I just want it to feel a bit more balanced while still having plenty of punch on demand.

I’d love to do a manual swap to get an extra gear ratio or three but that’s not in the budget for the foreseeable future.

What final drive ratio would you pick? Would dropping down to a 3.55:1 significantly hurt acceleration performance? Would 3.23s make the car feel dull?

Thanks for any opinions.
 
I like 3:23 for all around cruising. I swapped to 3:55 in my 499" in GTS but will probably swap back to 3:23, Joe
 
A 3.23 will kill that car. The tallest i'd go in your car is a 3.73. I've run them with your power level and it's a balance.

If and when an OD is in the budget you'll never go back. Running 4.56's with an OD at your power level is perfect.
 
roccodart440 said:
A 3.23 will kill that car. The tallest i'd go in your car is a 3.73. I've run them with your power level and it's a balance.

If and when an OD is in the budget you'll never go back. Running 4.56's with an OD at your power level is perfect.
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What size tire with the 4.56?
 
A stroker should have enough torque to pull a 3.23 like a freight train and still smoke the tires.
 
No less than 3.23,no more than 3.91.
What vehicle? What weight? What goal?
I have the 408 in my 64 Barracuda,3.55s, but I have a low first gear,plenty of go power.
 
toolmanmike said:
A stroker should have enough torque to pull a 3.23 like a freight train and still smoke the tires.
Click to expand...

I make 575ft/lbs and noticed a difference going from 4.56 to 4.10's. I can't imagine 3.23's.
 
My 410 stroker is well known as the slowest stroker on the internet and with the four-speed and 355 gears I absolutely have to have street drag radials to get any kind of traction with 28 in tall tires...
My cam is not anywhere in the ballpark of ridiculous anymore and I could easily see going to 323s but I am happy with the 355s coming off of the 410's...
And as a side note when I drag raced it I didn't see any significant gain going from 355 to 410...
 
j par said:
And as a side note when I drag raced it I didn't see any significant gain going from 355 to 410...
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You should have been in a completely different gear with that big of a change. I.e. with 4.56 I was trapping at 5,200 in OD (GVOD) and with 4.10 I trap at 6,200 in 3rd gear with a 727.

I'm unsure what you think a significant gain is, but if you went from 4.10 to 3.55 with no change in trap gear, trap RPM or 60 ft time it is a little beyond my understanding.
 
I have a similar combo to yours, 3:91's works great but eats fuel and buzzing around 3200 at 50mph. I just changed to 3:55's . No data yet but I will post once I get the car out of winter hibernation.
 
roccodart440 said:
You should have been in a completely different gear with that big of a change. I.e. with 4.56 I was trapping at 5,200 in OD (GVOD) and with 4.10 I trap at 6,200 in 3rd gear with a 727.

I'm unsure what you think a significant gain is, but if you went from 4.10 to 3.55 with no change in trap gear, trap RPM or 60 ft time it is a little beyond my understanding.
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Selective quoting must be inherited from another part of the Forum... LOL...
If you quote the first sentence of my post the picture become a little more clear...
Almost everybody's car out here on the Internet is faster than mine and of course the biggest thing they go to is they know how to tune and drive yet odd that 98% of them can't produce a time slip...
 
AAndrews said:
I have a similar combo to yours, 3:91's works great but eats fuel and buzzing around 3200 at 50mph. I just changed to 3:55's . No data yet but I will post once I get the car out of winter hibernation.
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Your speedo or tach are off.

2,350RPM at 50MPH.
 
j par said:
My 410 stroker is well known as the slowest stroker on the internet and with the four-speed and 355 gears I absolutely have to have street drag radials to get any kind of traction with 28 in tall tires...
My cam is not anywhere in the ballpark of ridiculous anymore and I could easily see going to 323s but I am happy with the 355s coming off of the 410's...
And as a side note when I drag raced it I didn't see any significant gain going from 355 to 410...
Click to expand...

HEre is the whole quote.

THis time i'll be more blunt. 3.55 to 4.10 will yield major changes in the 1/4 mile, including trap gear, trap RPM, ET and 60ft.

That's simple math. THis isn't the politics forum so your feelings don't matter.
 
I have GONE from 4.30s to a 3.23 in a similarly powered 65 Valiant. It still pulled like a freight train and the RPMs on the highway were very livable. With the 4.30s I was around 2800 or so. With the 3.23s I went down to around 2200. I never ran the car after the gear change, I sold it shortly after. No doubt it made a difference, but the car still pulled hard. If a car is powerful, it always will be, regardless of gear, you're simply going to "move" where that power can be used.
 
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323's and a 3000 stall..

a 3800 stall behind a stock 440 with a 484 cam at brake stalled 3400. the same converter installed in a small block 340 with a 465 lift cam stalled at 3000.

All the factory 340 cars I owned 68-71 brake stalled 2800 - 3000 most of them came with 323 gear sets and were a hand full on the street. Add a larger cam you must move the brake stall up which will increase the flash stall . This will keep the same feel of acceleration from a stop.

a 2200-2600 converter is for a RV/truck.

a lot of 340 4spd cars in 68-70 came with 391's

Then when they went to the 247 close ratio trans in 71 they saw the 355's were a much better gear and then most all 72 4spd cars came with 355's.

I like 323's with autos and an actual 3000 stall. Depending on your torque you may have to move up on the advertised stall to get your actual stall .

When I held my foot on the brake as hard as I could and stood on the throttle the tach would stop around 3000. Nailing the throttle at a dead stop would be flash stall I would get around 3400.

This may help you decide and many will have a different opinion. This was mine.

Governor and PTK solenoid. will also give you a feel you will like in an auto shift car. Once you have them you will never go back.
 
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Obviously 3.55s or 3.23s are the choice, and with a 408 and a decent stall converter, I think either will work for you.
If you want to retain the 26"tires, I would go with the 3.23. If you are open to a 28"tire, (and can fit them) then I would go to the 3.55s. If you have the 3.55s and want more go, you can use 26s. 3.55s and 28s are almost a tradeoff with 3.23s and 26s.
My choice? 3.23s, 28" tires, and a custom 3200 converter.....
 
roccodart440 said:
Your speedo or tach are off.

2,350RPM at 50MPH.
Click to expand...

We'll see. Just made sure I have the correct speedo gear, speedo and tach rebuilt and recalibrated by Mr Heaterbox.

Just for comparison sake , here's a chart from RMS that is pretty close to my results for the components Im using.

26" tire 3:91 gears 4-speed .

Chart says 3000rpm 59 MPH.

Thats closer to my actual experience than your 2350 post.

First run will be in May. I'll post the results.

Speed/Tire/RPM calculator
 
That's the calculator I used, I assumed a 28" tire, which yields 2,350@50mph with your gears.

2,550 @50mph with your 3.91's and 26" tires.
 
roccodart440 said:
That's the calculator I used, I assumed a 28" tire, which yields 2,350@50mph with your gears.

2,550 @50mph with your 3.91's and 26" tires.
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Yup! Again to your point, the speedo and tach have been recalibrated and I have the correct speedo gear installed for the 3:55's so I'm hoping for a significant RPM drop on the highway. Im looking forward to testing the theory!!
 
upload_2022-4-26_14-46-19.jpeg
 
I didn't have a stroker but I ran 12.8's with 3:23 gears, 3500 stall and 255/60/R15 Cooper Cobras. The stroker has lower end torque so you should be fine with 3:23's
 
I love my 3.23's and wouldn't change them and I don't make anywhere near the power you make Mike. Plus you'll be doing a little highway driving I'm sure.
 
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