3:54 vs 4:10 with a low deck 499

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forced 340

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I am building a almost 12:1 499 low deck for my 70 swinger. it will have TF 270's, solid flat tappet (for now), indy max wedge single plane, 1050ish dommy, rmvb 727 with lots of a&a goodies, lupo 9.5'' convertor (i'll be sending it in when i decide on gear ratio), 325/50-15 drag radial ''r''. my question is, has anyone run a similar set up with a 3:54? should i run the 4:10? i dont do a lot of freeway driving, but would like to. i am trying to keep the rpm's down while cruising too. i currently have a very nice, braced 8.75 with a 4:10 in the car now, but i have a dana ill be narrowing with the 3:54 factory gears. let me know what you guys think, and thanks for the advice!
 
I like it! With the 28.3 inch tire diameter and accounting for tire growth at highway speed your looking at between 2400-2500 crank rpm. It sounds like a whole lot of fun to me, should be able to blow the tires off at will at almost any speed...
 
You will have lower piston speeds with the 3.54 gearing, especially with the (?)4"(?) Stroke you will be running. I think that is something you may want to consider.

You are going to have more than enough torque with that B block in an A body that getting off the line won't be a problem.

Personally, I would go with a 470 build. It gives lower piston speeds, and greater compression height on the pistons which hypothetically should get you a longer engine life. The shorter stroke allows higher rpm's and you can take advantage of the 4.10 gearing just a little better.

Double check all of this with a calculator. Talk to @AJ/FormS about gearing and your trans ratios and tire sizes et cetera.
 
I’d be willing to bet it’d pull a Winnebago with 2.94 gears while towing your A body behind it...
 
Just got home, here's a book you may just want to add to your library. Really, just get the book, it's only twenty bucks.

https://www.amazon.com/dp/1934709476/?tag=fabo03-20

I don't want to get anyone in trouble for copyright violations so I am not going to take pics of the pages and post them up. I'll type in the formulas though.

Mean Piston Speed (in feet per minute) = stroke * RPM / 6
example ;
3 inch stroke, max rpm of 6,000
PS(fpm)=3*6000/6=3000fpm

Max Piston Speed = MPS
fpm = feet per minute
MPS(fpm) = (stroke * pi / 12) * RPM
using the same engine above;
MPS(fpm)=(3.000*3.14/12)*6000
MPS(fpm)=4,710

Piston Acceleration
1g=32fps^2

Max Acceleration = MA

MA = (RPM^2 * stroke / 2,189) * 1.33
same engine as above
MA=(6000^2*3/2189)*1.33
MA=65,767ft/sec^2
that's about 2,055 gravities! multiply that by the mass of the piston, and you can calculate how much weight is being placed on your rods, pins and pistons.

Now same thing with a 3.915" stroke for a 470 cid B block
MA=85,632ft/sec^2
2,676 gravities

Now same thing with a 4.150" stroke for a 499 cid B block
MA=90,977ft/sec^2
2,843 gravities

That's a difference of 167 gravities. How much do you REALLY benefit with that increased stroke. After having gone over these formulas I decided to NOT stroke my 360 to a 4" arm. The cost:benefit ratio just isn't there. I'll put the money in better heads, rev it higher and have a longer lived engine. Even with my 4.10 gearing

Calculating RPM limits

RPM = (desired piston speed * 6) / stroke

You need to contact your piston manufacturer to find out the safe limits on piston speed for your pistons... cast/hypereutectic/forged.
Keep in mind oil control with high piston speeds...
 
Also, check out the compression height differences between the 470 and 500 CID engines.

Stroker Kits-440 Source

470 = 1.480 compression height, rod length is 6.535"
vs
500 = 1.222 compression height, rod length is 6.760"

Do you need the better rod ratio enough?

That's a 0.258" difference, just a hair over a quarter inch. Is the bottom ring unsupported? What kind of piston rock will you get? Do you need extra long skirts to help make up? What kind of balancing needs done? (The balancing is probably a wash, but that's just a guess on my part).
 
in an a-body I'd do a 470 like suggested with the 240 tf heads if it 's a street car, a friend built that same motor with a 550 hyd cam 240 heads 11.0 comp, in a 63 belvedere with 3.91 gears, he ran it at the track 11.07 with lots of tuning left. single four bbl. 800 avs. pretty darn fast with no tuning.
 
I had 4.10s in my Charger for several years. It was absolutely snappy even though the car weighed almost 4000 lbs. It got maybe 5 mpg around town.
Freeway? I didn't do much freeway driving. 3800 rpms at 70 wasn't very much fun!
 
My guess is.... It will be no quicker at the track with the 4.10s, and a lot less comfy on the street. I would absolutely use the 3.54s, and the dana is a good idea.
Edit: quote" I'm trying to keep the rpms down while cruising too" Dr Diff now has 3.23 gears for a dana (new!). I think your engine would pull those too, and they are an excellent compromise gear (as is a 3.54.).
 
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I had 4.10s in my Charger for several years. It was absolutely snappy even though the car weighed almost 4000 lbs. It got maybe 5 mpg around town.
Freeway? I didn't do much freeway driving. 3800 rpms at 70 wasn't very much fun!

Yeah. I am somewhere around 4k at 75mph. It REALLY sucks the gas down, I get around 11mpg, and that's with my tired old 318. My commute went from 13 miles each way to 22 miles each way. No, it's NOT possible to drive slower. Snappy here too, and my compression ranges between 100 and 150. :eek:
 
wow!! thanks for all the great replies guys! this is great! i am really leaning toward the 3:54.
 
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