I think I want to get new rear-end gears for my '86 Z28 this summer...looking for a quicker "off the line"

I really don't know anything about the gear ratios. It's all gibberish to me. SO, If someone out there wants to educate me...please do so.

I have a 5.0L 305ci V8 that is definately a dog. My brother's 2.8 V6 keeps up with it until about 65-70mph. This is my only car so I need decent gas mileage (and I use decent loosely) 12-14mpg. Anyway, I know that the 305 has more power in it...I'm just new with cars and need some help finding it (the power).

As far as I know, mostly everything on the car is stock. I have noticed an Edlebrock intake manifold and a quadrajet carberator. Other than that I don't know much about it.

Here are some suggestions I have received so far:

-"get headers"...my thoughts: prob not many horses to get out of 'em for the $$$ ( I've got manifold with no muffler or cat)

-"get a cold air intake"...um...my carberator (air filter) has an intake on it now, is RAM air gonna do that much?

-"drop a 350 down in it"...ha!...$$$...might as well buy a new car.

-"try a limited slip"...I think this may be good for traction if I put in new gears.

-"swap to a manual tranny"...for the $$$, prob not worth it.

-"get a new car"...hehe maybe a good idea, but I wanna keep her.

-"gear the rear end differently"...?...don't know much about rear ends. hopin' someone can help me.

I am an 18yr old amatuer looking for experienced peoples opinions and knowledge. Also, any weblinks you have that would be useful are appreciated. Thanks!

 

Well I have several things to address. First off I have an '86 Firebird (probably similar to yours) with the 305 and all! I fealt it was a pretty strong engine for a time (it would bark the tires shifting into 2nd) and it was stock. (no Edelbrock intake) But here's some things that made OK power increases, definately worth the power.

1. An Accell new ingition module, distrubutor, and super coil on top. It improved gas mileage AND power! I got all of it from O'Reilly's for like $100.

2. An OPEN air intake, Ex. 12" open air element that K&N. ($50) Improved bottom power there.

Now onto your gears. If you want off the line I'd go with a 3.73:1 gear. I 'd make sure it's a posi, NOT a limited slip they're not that whoopy if you want traction. I bought a posi from Hawk's thirdgen parts for like $300 (not including shipping). Good guy to work with. (you can find his web banner on the main web page here) I haven't put it in replace of my 3.08 limited slip (which is probably what you have) yet. That gear ratio won't kill your gas mileage to much because you probably have a 700R4, which means you have a .75:1 (roughly) overdrive, which is good! The 3.73:1 will definately give you some NOTICEABLE off the line acceleration.

Now about that 305 and the headers, I wouldn't mess with it. If it's a "dog" don't spend all that money on something like headers, just start saving for that 350. (Or be like me and go for a big block...) I'm 20 and poor also, but just keep saving! (or join the military) Good luck with this!

 

The thing to remember is to match your gears to your cam's powerband. I'm not sure of the powerband of the LG4 cam, I would say 3:23s would most likely be the best, but if you plan on future mods, like a cam, you might pick out some better gears.

Why not get headers??, it will improve your performance and will bolt to a 350.

 

Without headers any other mod isn't going to meet its full potential, the engine chokes with those manifolds on there.
As far as Ram Air, if you have a single snorkel on black type thing on top of your carb, that's restrictive and putting an open element on will benefit you.

 

I just wanna say that headers are worth the money!!! Trust me, you'll feel the difference!!

 

um posi is limited slip. Posi is just the name gm used for limited slip. There are aftermarket ones out there but if he has a good working limited slip it should be fine. If he has an open rear(only spins one tire) then a posi would be might be a good investment, but I dont know what they make for the 26 spline axles.

 

Momar said it. Eaton makes a posi [limited slip] for the 26 spline axles. The only other thing would be a spool, NOT for the street.

 

If you want more off the line get a higher stall speed TC. I've heard this will do more for your ET than any gear swap.

 

I guess that the "no headers" thing would be a screw up on my end. I didn't realize they bolted up to a 350. I figured they would be to restrictive for one. Learn something new everyday.

 

Exactly, it's been shown in some cases to drop .5 seconds off, course a dramatic gear change with the right setup can yield the same.