307 to 410 gears?

[Ron's68]

I am switching from 307 to 410 gears. Has anyone done this and did it make a big difference in performance? I have a rebuilt motor and right now it will barely do a burn out with one leg. The rear tires are 295/50's which is a lot of rubber but the motor was suppose to put out close to 400hp. It dont fill like it. I hope this makes a difference. I can hardly wait. I would call in sick to finish it but my boss would'nt like it much.

[bigvinnie]

400 hp, 4.10 gears and fat rear meats sounds like a lot of fun, you'll definitely feel the difference.... rear tires won't last long with that setup.

Only problem might be higher rpm at hiway speeds, but you can fix that with an overdrive tranny...

[sixty8chev]

Sounds like you are already into the project, and i can tell ya its gonna be fun when ya got it done, i used to have a 4.10 posi and the 295s behind a mild 350/350 combo, and i had no problem smoking em
but a word of warning, with that set up your gonna be pushin three grand on the highway, and swithching to a 3.73 actually improved my 1/4 mile time, cause i was topping out around the 1/8th before, granted i don't rev my engine that high, but i just thought i'd give you my two cents
But either way, your gonna have fun at the line, and if ya like the tires ya got on there now, ya might wanna grab a cheap set to throw on for the first couple days of playin with the new setup.

[crazy longhorn]

yes, the 4.10s will be fun to play with! they are a little hard on tires & fuel mileage as already mentiond tho.....

[bigjimzlll]

you might look into some tunning too...even with those hi-way gears..with 300hp and a one legger you should be able to cook a tire..a engine thats not tunned correctly will not perform..also what kind of exhaust are you running? if put a restrictive exhaust on a big HP engine(400hp) is HUGE it will really hurt perfomance..from my experience..there are not a lot of 400 hp small blocks out there..my engine,which is a fairly hi-perormance build ran a 14.8 in the 1/4..that means my engines making around 320HP..and I have several thousands in it...now if your motor has a radical cam in it, and its designed to run in the high rpms..the 4.10s are really going to make it work..but if you have a stock stall converter, you might still have some problems off the line.
Jim

[slam33]

Make sure you have the right setup. 3.07 is a series 3 carrier and 4.10 is series 4.

[Longhorn Man]

With an engine that is supposed to put oput that much, you'll need other things to make it 'right'...
What is the stall rating on your torque converter?

[dion]

I choose 3.54's, I can still do 30 foot burn outs and go 85 on the Freeway without sounding like I'm getting ready to take off to the moon. 4.10 are great for city driving though.

[lukecp]

bigjimzll is right. With my 285 HP engine, and 3.07 one legger gears, my truck has no problem smoking the rear tires. Just hitting the gas will leave a mark 20-30 feet long, and if i "power brake" it will do it much longer. I have 255x60-15 tires if that matters. Personally, i think 4.10 gears are way too low unless you are going to rev your engine go 6000+ RPM. 3.73 would be a pretty good choice, and you would still be able to stand it when you drive on the highway.

[crazy longhorn]

Id say go 4.10s & dont even look back! you arent that much difference from 3.73 to 4.10......& you can always go to a bigger(taller) tire to help optimize the ratio. My 383 doesnt really need 4.10s, as there is enough lowend tork to move the truck. i may go from the 28" tall to a 29" tire to knock the revs down a tad, but Id be supprised if the eng was close to being topped out at the end of the 1/4 mile.....desk top dyno puts max power @5250, but the d@mn thing pulls good to 5800-6000, & will pull 6500 revs on the open hyway! Looking at the cam in your sig, comp claims you can run a stock verter......but i think you will do better with somewhere in the 2300-2500 range on stall. good luck...crazy man

[VDOG]

68 LWB, .040 over 350 with 10:1 pistons, balanced, vortec heads,comp 270H cam, air gap RPM manifold, holley 750, and gear drive to annoy the neighbors.


Ok here's my question, is this what you have in your engine now? If so, maybe you do need a stall converter. But even without one, you still should be able to smoke the tire with those items. Just by going with what you list, Dyno 2000 rates at 440hp and 430 tq. I added headers, and used a roller setup that im assuming you have. Do you have a build sheet?

[special70gmc]

my 350/350 with 4.10's squeels but it doesnt smoke the tires whats the deal? although i dont really have 400 horse like u guys though it goes pretty good though

[crazy longhorn]

I ran a mild 355 with the same driveline that i have now. she would just bark em a little & go. With the 383, it takes 2 lanes of pavement to hang on to that old longhorn till about 70mph! those strokers put out some pretty big tork numbers in the low & mid range, & its hp that sells engines for the shops........but the tork is what makes em fun!

[Dean23]

I'm thinking of going with 4.10 myself in stead of the stock 3.73 but im gonna be running a 700r4 so revs wont be aproblem. 5.13's could be fun though.....

[Ron's68]

Hay people, thanks for the replies. My motor is a .040 over 350 with 10:1 hypertunetic pistons. Stock crank and rods but rotating assembly has been balanced. Vortec heads with spring upgrade. 1.5:1 roller tip rockers. Air gap intake. Right now I am running a stock HEI, but I have a new proform HEI in a box ready to go on. As soon as I'm done with the rear. I am also running a carter 625 carb because my 750 holley would sputter of idle. Once moving the Holley seemed to produce more power. I also have a stock torque converter on it. (I think that should be my next investment.) The motor has about 800 miles on it. Once it got rolling it pulled real hard, but if I punch it off the line it would bog. I have some cheep torque thrust headers and mufflers. but right after the muffler my exhaust drops to a smaller diameter tube. I think 2". I am planning on cutting it off and having turn downs right in front of the rear end. I know that exhaust is hurting performance, but I thought it would only be top end performance. I have done a lot of work in the last two months sense the last time I drove it. I replaced the 1987 truck sepintine belt system with aluminum pulleys and Alan Grove brackets. I removed the clutch fan and installed an elec. fan. And I'm almost done with the rear end. By the way, I already bought the 4.10 gears so I am stuck with them. In the future I would like to go back to a 700r4 trans. It had one in it when I bought it. Um, sorry for rambling, I'm at work and I like this site better than working. Well my truck will be back on the road this weekend and next week I will let you all now how it runs.