3.23 to 3.55 or 3.73

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MoparMark91

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Hey guys so right now I'm debating on a gear ratio to go with as I am going to upgrade from 3.23 open. Don't know whether to go 3.55 or 3.73

340 bored and stroked to 373
727 tranny
215/60/14 tires(will change soon bump it up a little)

3200 stall 10 1/2 converter
Also my cam is a XE275HL
231 intake at 50


Any input is helpful as I don't do a bunch of highway driving but some times I go for a cruise.
Just want good ratio that will launch good with my setup and not sure how my converter comes into at with all this. I'm leaning on the 3.73 but I do want to get some opinions from experienced ppl with this
 
3.73s are the perfect gear that's what have and 55 comes in at 2,900 or so with my converter. I just drove 155 miles to the Automotion show in Wisconsin dells and in july i was drag racing running my best times.
 
With that size tire you will be around 3300 rpms at 65mph with the 3.73 and 3100 with the 3.55s if you dont plan on doing a lot of interstate travel I'd go with the 3.73s
 
With that size tire you will be around 3300 rpms at 65mph with the 3.73 and 3100 with the 3.55s if you dont plan on doing a lot of interstate travel I'd go with the 3.73s
Don't plan on doing a bunch but like maybe small town to town trips or like old roads stuff like that so maybe I will stick with 3.73 then and go that route
 
I switched from 3.23 to 3.73
Daily driver mostly in town
Works excellent!!
2200 rpm = 45 mph.
3400 rpm = 75 mph
With 255 x 60 x 15
The gear change only increased the rpms about 300 to go the same speed.
 
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I switched from 3.23 to 3.73
Daily driver mostly in town
Works excellent!!
2200 rpm = 45 mph.
3400 rpm = 75 mph
With 255 x 60 x 15
Awesome yeah I think that it's something that will complete the drivetrain build for me besides getting bigger tires, did u have to tub the rear to fit those? I was always think biggest to fit in rear was 235s
 
I'd go with 3.73, all of them is probably under geared for best performance.
 
I'm not following you? lol
You really wouldn't want to. This happened at 56 LOL

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Awesome yeah I think that it's something that will complete the drivetrain build for me besides getting bigger tires, did u have to tub the rear to fit those? I was always think biggest to fit in rear was 235s
No modifications
They just barely clear, it has about a 1/4" gap to the leaf springs.
That's with a 7" wide wheel.
4 1/2" back spacing I think...I'll check to be sure
 
No modifications
They just barely clear, it has about a 1/4" gap to the leaf springs.
That's with a 7" wide wheel.
4 1/2" back spacing I think...I'll check to be sure
Yeah if u dont mind let me know cause then that's my next change up is my wheels lol
 
--- Ouch !! -- Hope that no one was hurt.
No hurt but the memories from it being with me a very long time. The feel of that motor coming alive again will be great. 829 @ 7900. One Day I'll hear her sing again wearing another dress with a lot less weight. Here's a clue


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Punch-line at the bottom, in case @rumblefish360 is lurking.
with 215/60-14 tires it don't matter what gears you run; that 230* equipped 340 will be spinning to past the speed limit (around here anyway); so just put a "posi" in it and let her buck.
That 230* cam should power-peak at around 5200, which being 88mph with 3.23s, in second gear, if the tires ain't still aspinning.

For myself;
>Because of that tire handicap, for myself, I would have chosen a cam one or maybe even two sizes smaller,and a 2800TC, and so, extend the powerband down to where I will be actually driving for the vast majority of the time.
>Because of the city application, I would have chosen 3.73s to put the Second-gear power peak closer to where I will driving most of the time.
> I will never be at WOT in third gear, in any city, in my neck of the woods, so third-gear performance to me is irrelevant.
>And I would put the fattest tallest tires that I could fit in the tubs, even going to the extent of moving the springs and narrowing the rear-end. Say I get 28s in there.
>Ok now I am set up for 32mph = 3500 in first/2100 in second.
At 3500, it doesn't matter what my stall is; it is long ago coupled.
And 3500 is roughly where the torque-peak is , so I know, that when I stomp it, even with a 220* cam,as long as I have some decent cylinder pressure, chit is gonna happen.
> and 3.73s with 28s makes 65=4850@15% slip in the 2800TC in second gear; right about where a 220* cam peaks.
> and 3.73s will get me a cruise-rpm of; 60@2680 /65@2900 in third.
> because of the short-period cam I chose,I would need to fatten up the low-to midrange power, so; I would send my heads out for some appropriate porting work, and I would find a cam with lots of lift, and/or I would choose 1.6 rockers.
That's what I would do in a tub-challenged A-body.
In a swb Duster/Demon/2nd gen Barracuda, which all have generous tubs, I would sacrifice a lil tire height, to get a lil more tire width. You can never have too much sideways rubber, cuz the brakes don't work when power-sliding around the turns, on city streets; and curbs cost you money when you smash your 10" wheels into them. With the fat rear tires, you can however, increase the rear brake proportioning to haul you down when NOT sliding,lol. So when you see trouble coming, maybe you can brake early enough to keep the wheels off the curbs.

More than anything, those 215s gotta go, before you ever turn even 1 mile on the odo. Those are disaster magnets. Your combo will zero to sixty in, between 5 and 6 seconds. In 3 or 4 seconds, those tires can have you upside down,on fire, and sliding backwards, at 300mph......
or something like that,lol.


Ok but if the 230 cam is already bought/installed, that will bump up the powerpeak ~300 to 400 rpm, so say 8%. Just install 8% more rear gear, and and that will bring the Second-gear power back to where you need it, so 3.91/4.10s. And the 3200TC will be happy with that. Unfortunately, first gear with 4.10s and a 3200TC, is sorta useless, now just being the gear to get you into Second, where all the fun will be.

And here's the rub. 4.10 x 1.45=5.95 gear ratio, the ratio your engine is gonna spend most of it's life. And 5.95/2.45=2.43s in first gear
What that means is you could have 2.43s in the back and be in first gear, for exactly the same 4.10/1.45 performance.
And what that means, is you could theoretically stretch first gear to 60=5500 with 2.76s and fat 27"tires.
Hmmmmmmmmmmm, decision, decisions.
To pull that off, you need some first gear torque. That 3200TC is gonna help you, but in addition, you will need decent Cylinder Pressure.
And the engine will want some tirespin to get up into the powerband, no the 215s are still out. But say 255s.instead of 295s.

Ok so now, I can tell you, that I have run everyone of these combos I have been talking about, having been a streeter all my driving life, since 1969. On the street absolute power means pretty much nothing to me. 300hp is more than enough to have a lot of fun with, if you have a well-engineered combo.
But having the right amount of power at the right time is absolute king; and by power I mean torque, because on the street, say it with me; absolute power means almost nothing. I'd rather have 350 footpounds at 32 mph than 420hp at 5200rpm. The former is usefull. The latter is killer expensive for killer tiresmoke, and that , while making killer-smiles, is way overkiller. lol, IMO,already having a ~400+ hp 367,lol. It's more than killer fun. It takes some skill to keep it between the ditches. Whereas 300hp with adequate tires, is a point and shoot deal.
Ok enough talk.
the point I wanted to make is this;
put a SureGrip in your 3.23s and mount some more serious tires on the back, and just drive it. In a few hundred miles you will know if the 340 can or cannot pull off those gears, and what you might have to do to satisfy your craving..
 
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Yeah if u dont mind let me know cause then that's my next change up is my wheels lol
These are the rear wheels on my car.
Their 15x7 small 4" bolt pattern 4 1/4" backspace
They have them with large 4 1/2" bolt pattern too.
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These are the rear wheels on my car.
Their 15x7 small 4" bolt pattern 4 1/4" backspace
They have them with large 4 1/2" bolt pattern too.View attachment 1715593723
Alright thanks yeah i do want to upgrade my tie size. i have 5x4 bolt pattern i hate the selection but got to do something. are 5x4 axles able to be swapped with 5x4.5? Can you just pull out one and put in the other?
 
Alright thanks yeah i do want to upgrade my tie size. i have 5x4 bolt pattern i hate the selection but got to do something. are 5x4 axles able to be swapped with 5x4.5? Can you just pull out one and put in the other?
You can swap axles yes.
That will also give you way more wheel selection.
I haven't and I'm ok with small pattern
Plus nobody wants to steel them...lol
My car still has drum brakes on all four
If I upgrade to disks someday then I'll change to L bolt pattern.
Just got off the freeway
I was off on Hwy speed and rpms
3500 is 70 mph with 3.73 and 255x60x15
Checked in my car with gps..
I get better mileage in town then hwy...lol
But that's where I drive 99%
Good luck with you're car, I really like the 3.73's
 
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