shotwell36

Long time stalker first time poster. I've had my Camaro for a year and am getting the itch to hop-up the little v8. It's a 92 Polo Green T-top RS with an all stock 305 and 700R4. Only thing is has is an open air cleaner. I am not engine-swapping because it runs so good and has never given me trouble and for the sake of keeping it original (insert 305 bashing here). Doesn't leak a drop, no pings, knocks, or ck eng light. I have grown to love the small engine and want to do it justice and make it all that it can be. I am looking into porting the heads at a good machine shop here, cam swap (nothing too wild), intake, rear gear swap (has factory 2.43), shift kit, etc. My goal is a streetable hotrod without breaking the bank. I know the 305 is limited in output but it suits my desires. I am open to all suggestions and wiser advice. I'm a driveway do it yourselfer just seeking the advice of pro's! Please fill me in on what you think. Any info and specs help!

Ja85z28

1985 Z28 5 speed matching numbers original 56,700 miles. Aerohead Racing prepared 601's complete with 1.94/1.50 valves, bowls blended, and gasket matched. Summit K1103 cam/lifters 214/224 @ .050 443-465 lift, Comp Cams roller-tip rockers/push rods, Melling timing chain, and complete Cometics gasket set (zero leaks!). Factory exhaust manifolds feed a stainless steel SLP Y-PIPE, 3" exhaust pipe from the "high-flow" catalytic converter to a Flowmaster muffler w/ dual 2" tail pipes. My performance goal was to simply wake-up the 305, but retain the original look. She purrs like a kitten.

Here's a little video http://youtu.be/Fle9A6RC1E8

Biledriver

If it runs that good maybe you should just do some gears and leave it be. Check for a good tune up and timing. I'm sure plenty of us have messed up great running cars in the name of performance.

Ja85z28

A 2800-3000 stall and 3:42 gears would be an excellent place to start. Don't buy a cheap torque converter. I have had good performance out of both Circle D and Precision Industries.

shotwell36

Really really great looking and sounding car. I noticed you have a flat tappet but I thought the L03 was a roller motor. Is it difficult to make the switch or have benefits?

shotwell36

Are rear gears in these as hard to swap as a lot of people say?

Ja85z28

My car came with a LG4 engine . Stay with your roller hydraulic lifters, because they're all around better than flat tappets. GM12370845 would be a comparable to my cam, but with hydraulic roller lifters. http://www.kendrick-auto.com/chevrolet-factory-cam-specs/

Gears can be a daunting task and should be left up to highly experienced amateur or professional Mechanic.

I really think a quality torque converter is one of best performance modifications that you can make. Call Chris at Circle D and he'll spec a converter that won't effect driveability, yet really make you smile.

After gears and converter, I suggest that you address your exhaust system.

305sbc

iTrader: (3)

Leave the gears alone and get a pro Yank 3400 converter. It's expensive but well worth it in performance, and you won't lose any mileage or have to worry about gears or fixing your speedo.

90HSR406

That ^^^ I did exactly that. It's an animal now though. A pet chimpanzee to be exact. Docile and well behaved until it rips my face off. Then it gets fixed and I start the cycle all over again because "it will be different this time" lol

GeneralDisorder

iTrader: (1)

3000 stall converter, shift kit, and 3.70 gears.

Totally different car.

That's my setup anyway. 86 Trans Am. Stock LB9. Lots of fun and haven't done anything to the engine yet.

As to not changing the gear ratio to save fuel economy.... did you buy this car for fuel economy? Nuf said.

Gear ratio and converter stall are going to make the biggest difference for the least amount of effort and money.

Shift kit will allow it to drop into second hard enough to bark the tires with the stall and gearing. Even with the stock 305.

1.6 rockers are an inexpensive bolt on. Do your valve stem seals, change the springs, and add the 1.6 rockers. Easy, cheap upgrade while doing the stem seal maintenance.

GD

brettr81

What is your budget?

NoEmissions84TA

iTrader: (1)

C'mon guys. The single greatest upgrade you can do to these cars that gives the biggest bang for the buck is getting rid of the factory "T" pipe and replace it with one with a nice smooth "Y". Keep using your manifolds.

dmccain

iTrader: (2)

I went from 2.73 gears to 3.73s and it made a world of difference and didn't hurt gas mileage much at all. I still get over 25mpg. I also have an s10 torque converter (maybe 2100-2300 stall) and corvette servo and shift kit. 3in exhaust- cat-delete ofcourse. Lil bigger springs in my throttle body and custom chip. Made the car much more fun to drive big seat of pants difference. Headers and a good y-pipe would probably make a big difference also I just haven't fooled with it because I'm probably going with a 350 in the near future.

MoJoe

iTrader: (5)

My $.02, in order of upgrades:

1. 3.23 gears - Since you have to ask, have a shop do it. It is easy enough to remove the rear, and taking just the rear to the shop makes the gear setup that much easier that the shop should charge less labor.
2. exhaust - Y pipe = manifold to cat (inexpensive, if no rusty bolts, easy bolt-on)
3. exhaust - cat-back (cheaper and easier than converter)
4. quality 2800rpm torque converter (difficulty is dropping the trans)
5. headers (Dyno Don) - if you are definitely getting to this point, skip the Y-pipe above.
6. Vortec heads & intake - make sure you get the 305 specific heads with 58?cc chamber instead of 350's 64cc.

Jorlain

iTrader: (4)

When you're going to do piecemeal upgrades, you'll want to start with the things that are the biggest restriction to potential power. Most of these guys are right about the exhaust - huge restriction. I wouldn't bother with a torque converter until\unless you start making more power higher in the torque band. Putting a 3000 stall converter on an otherwise stock 305 is silly.

My recommendation, in order of priority.

1) Exhaust - Any short-tube header, decent Y-Pipe, Hi flow cat (if applicable. If you're exempt, get rid of it), and a 3" cat back exhaust with a straight through muffler (such as a Mangaflow or Dynomax Ultra Flo). Dyno Don headers are overkill for a NA 305 in most cases. You'll want a 1.625" primary. The 1.625" will give you a little to grow into without being overkill.

2) This: https://www.thirdgen.org/ultimatetbi/

3) Complete axle from a 98-02 4th Gen - This will be your best bang for the buck as far as changing your gear ratio. You'll get a 3.42 ring & pinion, a Torsen limited-slip differential that you will never break, and it's all setup to go - no paying someone else to setup gears for you. You'll also get a sorely needed rear brake upgrade if you can get the entire housing, caliper to caliper. This axle is a couple of inches wider, so you may show a bit more tire in the rear, but it should still be within the lip of the fender well.


After those three things, your options become far more grandiose. You start to look at tearing down your engine and doing a head\cam swap. Of course, when changing to Vortec heads, you need a new intake, etc. After doing heads\cam, at that point you may want to select a new torque converter that corresponds to your new upgrades\cam. And then you need to do a tune, maybe swap injectors, etc. Frankly, if you're at this point, you would be better off building a 350 to swap in some day, since you have to pull your engine (or at least your transmission) anyways. And then, all of the mods that you've done are compatible with that CID upgrade.

brettr81

Here

https://www.thirdgen.org/ultimatetbi/

https://www.thirdgen.org/ultimatetbi2/

If you can afford to be without this car for a week or so (not saying it takes this long, but life happens and we all move slower than we want at times). I'd just pull the engine, replace the torque converter with the S-10 V6 TC. Replace the cam (should probably do the valve springs, and seals as well). Since the intake has to be removed for a cam swap, BAM perfect time to replace intake. Since no engine in car, clean the engine bay (clean engine bays are sexy) and put that restrictive 2.25" Y pipe and exhaust (same size as the V6 exhaust) in a bin to be recycled or turned into modern art.

The exhaust is undersized on these cars. I'd do an exhaust headers back, before doing gears. Some people say 3" pipe, some say 2.5". These cars are one 170 hp. Yes, if you replace the intake, exhaust, new tune (stock tune for TBIs is pretty crappy), new cam (the cam in this is probably the crappiest cam ever put in a car by GM), you will be over 250 hp which is about what 2.5" flows best until. However, the difference hp loss up until 300 hp doesn't really necessitate going up to 3" on a street driven car. Higher diameter changes where you make power and moves it up the RPM range, going too wide on primaries, Y-pipe and exhaust in a 305, and you will lose a lot of low end torque.

Intake, intakes aren't too much money, and can be swapped in a couple of hours by almost anyone that can read and wrench. I believe user Fast355 is the expert of all things L03 and if you look at his posts you will see loads of information about these engines.

Personally, I wouldn't bother until gears or torque converter. I wouldn't do unless I was pulling the engine, and then I'd probably just go with the 4.3 V6 S-10 converter. Mainly because I drive my car to go places.

For gears, I'd do those after the header and intake. Gears can make your car more fun, but affect gas mileage.

Ja85z28

Sage advice! I should have addressed my exhaust system before heads and cam, but I couldn't keep my hands off the engine. My 305 didn't really come alive until after I upgraded the exhaust system.

brettr81

Jorlain, you posted as I was typing!! Also, look up the posts by Fast355. He is pretty much the expert at the L03 and swirl port heads.

The rear, I wouldn't go with a fourth gen, but that's because they are slightly longer and make your stock wheels stick out more. You can get 4th gen carriers cheap. I'd probably just look at either junk yards near you, or get the fourth gen carrier and have a shop put it in for you and change the gears to what you want.

Jorlain

iTrader: (4)

The width is negligible. It's already setup and ready to go. Paying a shop a few hundred bucks to MAYBE do a good job swapping in the differential isn't a gamble I'd be willing to take. But then again, I live in the boonies without a lot of options around for that sort of thing. I trust the job the factory did.