3.55's 4.10's or 4.56's?

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Shainesboostin

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Got my first Mopar recently. 318 70 Dart. has manual everything, 8.75 rear, 904 trans. Making it a fun street car. Doing a 5.9 Magnum swap as we started buying stuff for the 318 and felt like this would be a better option. Airgap manifold, 750 carb, headers, new distributor, msd ignition. Has 3.55s now, thought about swapping for 4.10s or even 4.56s? I know that may be a bit much, but wanted others opinions.
 
stick with the 3.55 for a cruiser, choose a camshaft wisely. I just swapped 4.10's in, been running 4.56 for too long. My combo needs over 4.
 
4.10's in the street is a lot. It also depends on tire size.
 
I just drove my 4.10 rear gear 11 sec car to work today! 38 miles ea way! Did 3100 rpm on highway and laid more then one patch of rubber. Just be honest with yourself man!!! Wanna go fast? Real fast? Then you need more then stock 360. Want to do but outs and impress your buddies? 3.91 rear gear! Wanna hate driving your car more then 10 miles? 4.56 or taller gears. Take it or leave it man. My ride is loud as all hell, roudy as **** and obnoxious as a red headed step child but I love it! You need heads, stall and cam to make 4:10 or steeper work. Just don't step outside the peramiter on any one of those parts and it will be fine!

Cut and dry......

For a toy car around town, I'd run 3.91 with at least 26" tall tires
 
all depends on intended use...

had 3.91 gears and it was awesome around town and drag strip. sucked when i wanted to get on the highway and go places.

had 3.55 gears and it was a little better on the highway but still not great and it was still fun around town..

put 2.94 gears in the car and loved them.. still had enough bottom end to make the car fun around town and i could get up on the highway and cruise the way i wanted to..

jamies dart has the 2.94 gears in it right now.. probably put a 3.23 gear that i have in it this winter.

i prefer to go long distances. i don't have OD so i prefer gears better on the highway. but its all personal preference..
 
"street car", "fun"...... = very subjective working.

My advice to you is save your money you'd spend on those gears and save up for a GVOD or some other OD transmission.

I run 4.56's and turn 2500rpm at 60mph. fun and streetable.

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Now if you pursue your original plan though 3:55, 3:73 or 3:91 is the answer to what you want.

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Last, if you EVER plan on going to the strip, really figure out where you want to be going through the traps and gear it down one notch from there. I found out the hard way that I should have went with a 4:30 gear if I really wanted the perfect street and strip gear.
 
abodyjoe said:
all depends on intended use...

had 3.91 gears and it was awesome around town and drag strip. sucked when i wanted to get on the highway and go places.

had 3.55 gears and it was a little better on the highway but still not great and it was still fun around town..

put 2.94 gears in the car and loved them.. still had enough bottom end to make the car fun around town and i could get up on the highway and cruise the way i wanted to..

jamies dart has the 2.94 gears in it right now.. probably put a 3.23 gear that i have in it this winter.

i prefer to go long distances. i don't have OD so i prefer gears better on the highway. but its all personal preference..
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I agree with this a lot. Had 3.91 with a healthy 340/4 spd with 14" tires. It was super fun for about a week. I think 3.23 and the OD transmission would be perfect. If no over drive that 2.94 sounds like it would be nice. You will enjoy your car way more in the long run. Don't worry about the bottom end and drag racing because the reality is that there an awful lots of low 13 second sedans out there that would likey still be you in a drag race, like the Infiniti Q50 400 horse model and many more. Make it a cruiser and enjoy. IMHO.
 
leave the 3.55 for now
when you do the 5.9 Magnum swap
put a a-500 trans in at the same time, with 4.10 gears

My 72 Dart is street / strip
540, 518 trans with a Dana 3.73 true trac and 325/50-15
 
I have 3.91 locker in my 64 Sport Fury that i built to go fast. I have 275/60 on the rear. I think they are 28 inches tall.
I put 3.73 in my 65 Comet. That was built more of a performance street car. I hated it. Put taller tires in it. 255/60, and it was better. I put a 5 speed in it, and i can run 70-75 if i want. I still think it would be nicer to drive with 3.55s . Have to shift out of first too soon, due to the steep 1st gear.
The 69 340 Dart has factory 3.55 Sure grip. 727 trans .i think these gears are great for an all around performance car with no O/D. 3.23 would be better for more highway use. As others stated, evaluate your intended use honestly, and then decide.
 
I had a 3.73 (GM ratio), in a 8-3/4" case, in a 11 second Dart. - Great set-up. - I suggest 3.55s. - Others cause too many RPMs for the street.
 
I'm running 3.55's with a 28" tall tire. 60 m.p.h. is right around 2900 rpm. Pretty nice for cruising and still fun in town.

Ted
 
other opinions?? your first build/mopar..fun street car??
first read Rusty Rat Rods guide and then
scrap the air gap and get a stock or stock style manifold like the RPM
scrap the 750 and get a 600 or 650
scrap the headers and use hi flo manifolds
scrap the 3.55's.3.91's ,4.10's etc and go 3.23
scrap the msd and go stock mopar ignition

...if your racing to the big end it would change everything
 
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How fast do you want to go? If I was building it , on somewhat of a low budget : 5.9 short block , EQ heads with la intake pattern, Air gap, 650-750 DP, 230ish at .050 , quality 10 inch (or 9.5) converter, keep the 3.55s. Should be easy 12s and run down the highway good. If you find yourself driving on the highway a lot, you may prefer less gear. If you rarely get out of town, you may prefer more. My old Mopars are also my daily drivers so I have 2.76s in one , 3.23s in the other. It is my opinion that the proper converter will have a greater effect on the launch than the gear ratio. A big cammed small block coupled to a low stall speed is going to be a dog even with 4.10s. On the other hand , the same engine used with the correct converter will launch hard, even with 3.23s.
 
I'm running a 408 with a custom stall converter (around 3200) a 28 inch tall tire and 3.23 gears
I churn our 3000 RPM at 70 MPH
and cant get traction for the life of me
 
i run 3.55 with a 24 inch tall tire and i border line hate it to the point i feel like i wanna trailer the car to places i used to drive it (150-200 miles round trip). good share of that has to do with the big lumpy cam and other stuff but over all if you wanna drive it a lot more that short distances 3.55 should be good for you.
 
1970-dart said:
i run 3.55 with a 24 inch tall tire and i border line hate it to the point i feel like i wanna trailer the car to places i used to drive it (150-200 miles round trip). good share of that has to do with the big lumpy cam and other stuff but over all if you wanna drive it a lot more that short distances 3.55 should be good for you.
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That is a very short tire. Have you considered a taller tire? Just a switch to a 27 inch would drop about 300 rpm at 70 mph.
 
forphorty said:
That is a very short tire. Have you considered a taller tire? Just a switch to a 27 inch would drop about 300 rpm at 70 mph.
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after actually looking the tire is a little over 25 inches tall but in the whole scheme of things it don't make much difference lol
 
Marcohotrod said:
rear tire size has a big affect on gearing, my N50-15 M+H is 28"
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abodyjoe said:
all depends on intended use...

had 3.91 gears and it was awesome around town and drag strip. sucked when i wanted to get on the highway and go places.

had 3.55 gears and it was a little better on the highway but still not great and it was still fun around town..

put 2.94 gears in the car and loved them.. still had enough bottom end to make the car fun around town and i could get up on the highway and cruise the way i wanted to..

jamies dart has the 2.94 gears in it right now.. probably put a 3.23 gear that i have in it this winter.

i prefer to go long distances. i don't have OD so i prefer gears better on the highway. but its all personal preference..
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Hi Joe long time no see. Getting back to this subject, I am running 276 gears in the Dart, of course with a Blown Hemi I don't need anymore, it will destroy the tires under it no problem. With out an overdrive its tough to run lower than a 3:91. Like some of the Guys mentioned tire size, convertor and cam profile play a big roll in gear selection. To build an overdrive for one isn't too hard, but it takes money. My advice, sit down and be honest with your self as to what you want to do with your car. Outside of what I have mentioned this will be what will tell you what gear to run. A good all around gear is a 3:55, how ever 3:91 will work, but will make RPM at 60 mph and up. If anyone would like a great site for Automotive Calculators, try Walace Calculators, Here`s the link, Wallace Racing - Automotive Calculators
 
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DusTed74 said:
I'm running 3.55's with a 28" tall tire. 60 m.p.h. is right around 2900 rpm. Pretty nice for cruising and still fun in town.

Ted
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You sir have a ton of convertor slip.

It should turn 2550RPM @60 with your combo.
 
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