I cant decide what gears i should get for my 8 inch, 3.55's or 3.73's. I do mostly town driving but if i am on the highway it is not for long. I have a built 302 with a comp cams extreme energy camshaft with 512 lift and 280 duration(comp cams recommends low gears), heads that have been ported and have 1.94 intake valves and 1.60 ehaust valves, Headers, eledebrock performer manifold, holley 670 carb, speedpro pistons with about 9 to 1 compression. I built the motor to have a lot of low end power because i dont plan on highway driving too much. the tranny is a c4 from an 80's car with a 2500 stall, that was rebuilt with all new goodies including manual/automatic valve body. I also have 28 inch tall tires that are about 12 inches wide. I currently have 2.79s which are doing nothing but hurting my performance. What gears should i go with and what are the benefits?
Thanks so much
Matt
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3.73s, quicker acceleration over 3.55s but 3.55s are better gearing for highway, like you said you rarely do that and it wont kill you with 3.73s. I'm going to be ordering some 3.80s for my ford 8inch in my 65. good luck!
I have 3.80's with a 4-speed. You won't want to be on the highway very long at all, and forget about 75mph interstates. Your 28" tires will help, but it should be fairly similar to my manual with 25.6" tires.
You could get the 3.55's, and if they aren't enough, get a shorter tire.
if you don't do much freeway driving, then you'll probably be happier with 3.73's. I went with 3.55's only because I do occasionally hop on the freeway to get to car shows and what not. ANYTHING will be a neck breakin improvement over those 2.79's!!!
i am not going to lie, this is a really hard decisions to make. i have been on the fence for a while now and am trying to make up my mind. The longest i have ever been on the highway with the car has been 29 miles and i have only done that once, but although i primarily drive it around town, i would like to be able to go out on the highway, gas doesnt concern me it is more the over reving factor. Oh and by the way i should correct myself they dont make 3.73's for 8 inch rears the next size up is 3.80's i think!
Matt
3.55 are plenty for a C4...i wouldnt go to 3.73's or 4.11's unless you had an AOD. anybody know anyone that is looking for a C4 its rebuilt with a brand new torque converter...
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65 coupe
ford racing 340hp 302 roller block
600cfm edeldbrock w/ rpm intake
shorties, flowmasters-side exhaust
street/srip AOD
9' detroit locker w/ 4.11s, tubbed 4-link
ssbc disc brakes, shelby drop, 620s
3.73/4.11 first gear goes by WAY quick. The rpm difference between the two isnt much really. You have a tiny engine (to me at least) and I am rather fond of 3.42/3.55 gears for my larger engines. 3.55 works well for the 5.0 crowd so I dont see why it wouldnt work well for you too.
The cruise rpm difference between 3.50 and 3.70 isnt much either. I would say pick one and just run with it. The 28" tires you have will help with the higher speeds, and also provide a larger footprint than a shorter tire will, even if they are the same width. I run 28" tires with the 4.11 in my toy, 3.70 in one of the Formulas, and 3.42 in the GTO. The only one that is geared too deep is the 3.70 geared car, because it has an engine that makes 500ftlbs at idle and 550 at 4500rpm. So it doesnt ned that much gear, and it blows though the rpm too fast. Your car isnt like that, it needs a bit more gear.
but either one will work great. 3.55 or 3.73.. just pick one. its not a big deal.
3.55's or 3.73's
. i have been on the fence for a while now and am trying to make up my mind. The longest i have ever been on the highway with the car has been 29 miles and i have only done that once, but although i primarily drive it around town, i would like to be able to go out on the highway, gas doesnt concern me it is more the over reving factor. Oh and by the way i should correct myself they dont make 3.73's for 8 inch rears the next size up is 3.80's i think!
