Hey Guys, First time posting on this site, i have a question.

What in your opinion would be the best choice for performance, on a 305 Carburated small block, in a 83 Firebird. I have looked at a few high rise intake mainifolds, and diffrent carbs, what would be the best thing ? Forget gas cunsumption.

 

The stock ones are fine. Until you have upgraded a whole bunch of other things, they're not what's slowing your car down.

Since your car is the HO, you should have an electric fan, 3.73 gears, a good exhaust system from the cat back, the better cam, and higher compression than the run-of-the-mill LG4 or Crossfire cars. The one thing you should do first is a set of chassis-specific headers such as Edelbrock TES or SLP.

Resist the temptation to simply unbolt and re-bolt big obvious things that sit on top of your engine, and replace them with shiny new ones. That's not how you make a car go fast. That's how you lighten your car by way of the driver losing weight through the wallet.

Believe me, I know how to make a 83 L69 car go fast.

 

I dont have a electric fan, i have a regular fan, but i have everything else for my car. If i got the header's should i go with a true dual exaust ? i have the dual mufflers right now, buts its a Y pipe.

 

OK, so you don't have the HO then. Please remove that misinformation from your signature as it is not true.

You have the LG4. That is the Low Output 305 for that year. The difference is 145 HP vs. 190 HP. You can verify this by checking your VIN; if the 8th digit is H, you have the LG4. It would be a 7 if your car was a HO.

Your situation is substantially different from what it would be if you actually had the HO motor. In reality, there's even less reason to change your carb and intake; the rest of your car is even less able to reach their limits.

You need to follow the basic recipe for de-LG4ing a LG4. Keep in mind that the way to make a car faster is to identify the one thing that's slowing it down the most, and direct your attention and moeny toward that one thing; then find the next thing; and so on. It is NOT to just un-bolt and re-bolt the stuff you can see whan you pop the hood.

You need an exhaust, every single piece all at once, from the heads to the street. You don't have the good HO exhaust, you have the little weenie drinking-straw LG4 one. Get a chassis-specific set of headers, as mentioned above; BUT NOT FOR LG4. Get the ones for something like a 88 350 TPI. You need every piece, all the way through, all as a set, because nothing that's worth buying will fit to your current stuff. That means headers, a cat, and a cat-back. If any of it will fit LG4, it will retain the stock bottleneck, and is a waste of money. Don't bother with "true duals", they don't fit one of these cars well, and offer no performance gain over a well-designed (not your corner muffler shop's "custom" job) single mandrel-bent cat-back.

The next thing you need is a cam. You have the tiniest little thing GM ever put in a small block chevy. Its lobes can be concealed with Clearasil. I'd recommend a Comp XE256, with the lifters and valve springs to go with it.

After those things, you need a set of gears. At best you have 3.23s. They force your motor to always run at a very low RPM, too low to make good power. That's what makes you always want to hold it in a lower gear. Similarly, if your car is an automatic, it will benefit from a looser torque converter, so that the engine can reach its optimum power RPM sooner as you launch it.

Somewhere along the line you need an air cleaner. The best setup, better by far than an open element, is the L69 dual snorkel variety. It does away with the restrictive LG4 single snorkel, but also picks up cold dense air with lots of oxygen instead of hot air which contains less air molecules per cubic foot and therefore can burn less fuel per engine revolution.

After you do all those things, the next obstacle to performance is your heads. You could take the ones you have and put bigger valves in them and port them, or get a set of 305 S/R Torquers.

After all of that, you might be ready for an intake.

Notice that none of this involves anything that people can really see, except for headers. This is how to make it go faster, not how to make everybody oooh and aaaah over your chrome and polished aluminum.

 

RB knows what he's talking about, he's been around a while and knows his stuff. once you so all of the things he told you to do(although a stock head from an lg4 with the baby valves in it sits atop my 305 and i am running 13's[going with the S/R Torquers as my next big upgrade]) then buy a nice Edelbrock Performer RPM or Holley Street Dominator intake with either a holley 600 vacuum secondary(good street carb) or a holley 650 double pumper (for your high gas guzzeling 305 HO) join the allaiance(SP?) of fast 305's!

here is a pic of my little 305

 

Sorry, i thought my car really was an HO, but i guess not then. Yes, it does have an H on the VIN, darn.... oh well. Is it really worth all the work on the engine? Would it not make sense just to put a better engine in the car? And could i buy the 88 exuast like you said at hawks third gen, and still have everything fit? Sorry for all the questions but i really just got this car recently from a guy that pro streets cars, and its seems to be putting out over 145hp. Its a 5 speed, and the exuast still has a regular exaust manifold, but the rest of it is 2 1/2 wide pipe, with 2 mufflers, while all the other cars i see are always single muffler. Is it possible that there are things about this car that are upgraded, or am i just seriously misinformed

 

Dont know if this will make any diffrence, but my car is a S/E. Mabey that has somthing to do with it.....

 

Well, in the long run, yes it would.

On the other hand, that "better" engine will also need an exhaust... a cam... gears.... converter.... air cleaner.... without all of which it will be no better than what you have now.... see where we're going with this? Sometimes it pays to think of the car as a whole, not just the engine by itself. Do it right, and the stuff you buy now will apply just as much to a "better" engine as it does to this one.

Again, resist the temptation to un-bolt and re-bolt big shiny easy-to-get-to things on top of the engine. That's the straight and narrow path to a car that's no faster than it is now and a much lighter wallet, all at the same time.

 

I have an H.O. and it isn't an electric fan. It has the 5500 rpm redline, the badges, and the Rochester 4 barrel. And two 7's in the VIN code. It's a real H.O with no electric fan. Was it a option or something?

Engine Code: 305 ci V8 LU5 (1982), L69 (1983)

 

You damn right it drinks gas lol! I had to fill up at 130 miles, cost me 17 bucks.

 

yeah, mine gets about 15miles to a gallon. i have a 600vacuum secondary though(along with a crap torker II intake) once i get my new intake (holley street dominator) then i may see alittle more low end power and possibly better mileage. i really don't mine the bad mileage, i just wish i had another car as my daily driver....

 

Begin with the basics, new spark plugs, wires, cap and rotor and 02 sensor will go a long long way in upping the fuel economy. ANd don't forget a fresh oil change. Use the AC Delco PF 35 or PF 1218 filter (long style) Cross reference a 1988 Chevrolet van with a 350 at the parts counter.

Also remove your carb and clean it with a can of carb spray and pop in a new fuel and air filter.

Total input for a tune up is probably in the $35-40. If you get real ambitious, change your tranny fluid and filter, diffy fluids too.

It'll be a great starting point for future mods like headers and the like.

 

Sounds like somebody downgraded your car somewhere along the line.... at the very least put the power-robbing (like 8 HP or more) low performance fan in it, or maybe even stuck a whole LG4 into it. I'm sorry to hear that.

 

Is it true that a mechanical fan can flow more air than an electric? If it is true, does the flow rate ever become a limiting factor?

 

It don't seem to a be a LG4. Has the Rochester Carb hooked up, with what seems to be a stock distrib. It may have been downgraded though. I can't tell. I looked on car fax, and there is a record of something on there, but you gotta pay to see what it is. If anyone has unlimited reports could they do me a big favor?

Oh yea, reason I say it could have been wrecked is there is overspray in engine compartment, and that record. Don't know exactly, but want to find out. Anyway, is the the Unlimited records option for one month, or year, or forever?

 

Agreed! Lots of people overlook this step, this should be a pre-req. to any mods.

 

1) LG4's came with rochester quadrajets

2) The Carfax thing always says there's a record of something. It's usually nothing, maybe a switch of owners or something. I bought a carfax on my car because it said it had like 3 records which freaked me out, but once I bought it the 3 records were just registrations of the car!

3)As far as overspray on the engine area, check under the wheelwells, doorjambs, and hatch area. It was probably just repainted at some point, nothing to worry about....

PS- good luck with your buildup, the LG4 can be made fast, I've got a mildly modded LG4 and I keep up with a buddy of mine who has a 305tpi.

 

No way in hell the guy before me put a lg4 in it I would bet, after all, he made six figures...idk it pisses me off thinking it's a LG4, but could a LG4 SURVIVE past 5500 rpm? Not like WAY past 5500 (only beent here once, 6500+ in first) but when I get on bypass ramps, I wind it just into the red line. Is there ANY way I can be sure of this? That this is not a LG4? If it is, I'm ripping it out, as soon as me and my dad fix the jeep or restore the other one. Grrr.

 

You must not have an LG4, mine starts complaining at 4500rpm I can't imagine you got it up to 6500. Does it pull strong all the way up or lose power? At what rpm does it lose power? You must have an L69 with an upgraded intake, or a really beefed up LG4. Did you run the vin decoder yet? What did it say? You can also get the serial number off the engine and decode it.

PS- no need to hate on the LG4s................:lala: :lala: :lala:

 

You're right my84firebird, i like the little ol' engine. Its nice and fast as it is. Sure it could use a couple extra hundred horespower, but thats fine to.




Crazy little jumping puff ***** :lala: :lala: :lala:

 

Had an all stock L69 and it pulled good to about 5400 rpm, but
when over-reved by mistake I saw 6000-6200 on the tach.

 

Since I only have an LG4 do I have to worry about the rear if I do all the mods you mention above? What about the trans?

Thanks,

 

What rear do you have now? A posi is a must have, and you want a good ratio like a 3.42 or above. If you have 2.73's or 3.08's you should definitely upgrade. Your car will accelerate a lot faster with a higher ratio rear end.

As for the tranny the T-5's are pretty tough unless you seriously mod your engine. You may want to upgrade the clutch though.....

 

I have a 10 bolt, and I think it is a 3.23. Doesn't a numerically higher gear mean that it runs at a higher rpm? Is that compatible with a low rpm engine as is the 305? I wouldn't want to overspeed the engine...

 

i've got 3.73's in my car with a 305 (wich is what the L69 cars came with) and it works just great. about 2350rpms for 70 miles an hour with a 700r4 (.7:1 fourth gear) with your five speed, the 3.73's would be really nice.

 

Higher gears help the car get to speed quicker. It goes through the gears quicker. You'll be pulling higher rpms but not enough to hurt your engine. At 70mph you may go from 1400 rpm to like 1800rpm, nothing major. I've got a buddy with 3.73's in his 305tpi and it feels really really fast compared to my 305 with 3.08's. For a while I was convinced he had a 350!!! Gears really help, and they're often overlooked. I'm getting 3.73s as soon as I have the extra time/money....................