Well, a friend of mine is going to get a 1987 H.O. Ford Mustang GT 5-speed. Of course, this is going to smoke my 89 IROC with a 305 tbi and auto tranny. Now, because this is a girl that knows nothing about cars, and she's already rubbing it in my face how much faster her car will be (I test drove it, it is), I need ways to beat the pants off her. (No comments from the peanut gallery, please. hehe) I was thinking.. 670 cfm tbi and headers would be a good start...

But then I was thinking, instead of going with a tbi unit, how about a carb? SO, I have some questions about that.

How hard is it to keep the vehicle emmisions legal when you go from a tbi to a non-computer-controlled carb? This would have to be a daily driver, so it would also need to be somewhat fuel efficient. I'm getting 20+mpg right now with my TBI, how much of a change would I get with a carb?

(Oh, and if I was to get the carb, I'd get one of those carb/intake/cam/whatever else kits.)

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89 iroc-z 305 tbi
k&n filtercharger, open element air filter. nuffin' else

 

So no eolithic references to clubs and such eh? Let her win and her prize is? No? I could never say no to a woman who could drive. Oh well, I'll leave it for BOR or maybe Vader if he's feeling frisky today...

As for the performance thing, why not swap out to vortec heads and the new TBI vortec manifold? This would serve as an excellent foundation for a nice sleeper that has some serious potential for a street car. And you won't have too many headaches eh?


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"Perfection is a trifle dull. It is not the least of life’s ironies that this, which we all aim at, is better not quite achieved."

-W. Somerset Maugham

 

Enkil,

You're making this one too easy, so I won't even go there.

Heads and cam. Then you'll probably need a PROM, then some higher fuel pressure. In the interim, you can cheat the timing a little farther advanced, then use higher octane fuel. Check the Tech Articles about the easy way to increase your fuel pressure on the TBI. Make sure the air cleaner is not restrictive (not just the filter, but the air cleaner housing and ducts). Switch to a 180°F thermostat to keep the fuel and spark curves closer to the power end and away from the economy/emissions offsets. This would be a good time to flush the system, unless you are planning to jump on the new heads right away.

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Later,
Vader
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"No matter how hard you try you can't stop us now..."
Adobe Acrobat Reader 4.0

 

ok question? what are you doing with tbi on a iroc? that year all had tpi! oh if you go carb dont DONT get a edlebrock! ok fuel effeciet and carb dont go in the same sentence. you'd get more power with a carb but less mpg i've tried everything and cant get over 14mpg with a carb it just cant be done~*(sorry having bad edlebrock experince!) did someone switch it from tpi to tbi that you know of thats not right to have tbi on a iroc!

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1989 firebird formula

Mods: converted from T.B.I. to a carburator 305 to a 350. Flowmater exhaust,hedman shortie hedders,202 160 (882) heads,.447/.447 lift 222@.050 duration speed pro 327/350hp cam 350 .40 over (356) Edlebrock torker2 and a 600 edlebrock manual choke (1405)

Future mods performer rpm air gap intake (polished) comp roller cam, and way better headsa 400 defintely in the works!

 

On my last trip to Atlanta I got 24mpg with my carb.
ODB


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*I do custom performance mods on Edlebrock Performer carburetors (dualplane intake mods in the works),
White 1986 Irocz, 305 with iron #416 heads,
383 with aluminum TFS heads,
Edlebrock Performer-RPM intake and Performer #1407 carburetor, +110hp shot of crack, 700R-4 tranny, Vigilante 2400 lockup converter, 3.25:1 Ford 9" rear, Mcreary Road-Stars, SLP-stainless 1.75" shortie headers & Y-pipe, single 3" Borla exhaust, Linginfelter-TPI camshaft part number 74216 pulls 17" vacuum solid. Cam specs 213/219 @.050 114-LSA, sometimes advertised at 216/219 @.050 112-LSA .462/.470 lift @1.5:1 ratio. Using Harland Sharp 1.65:1 roller rockers. MSD-6AL, billet distributor, multi-retard, blaster-3 coil, and RPM switch. SouthSide machine subframe connectors, SSM lift-bars, Moroso 4" underdrive crank pulley.

N/A runs 10.9 @124,
Crack-runs 10.3 @135
haven't run at track since Oct-99

 

I get 32 with mine.

Oh yea... you know, Im sure she wouldnt notice the #7 plug wire being disconnected. Its the second from the back, driver side

[This message has been edited by madmax (edited February 13, 2001).]

 

lol... good idea madmax..

Burnout: Well, apparently they didn't all come with TPI units. The vin number says I have an 89 305 tbi unit in it as well, so.. it's not like the previous owner did a swap.

 

Not too many chicks can race a 5 speed to save their life. You're a long way from beating her except for if she misses a gear, but thats pretty good odds.
lol, zipping my flame suit up...sorry ladies, i've only seen a few girls who can race a 5 speed. Not drive one (though i have never met a girl who didn't ride her clutch too much.) BTW, if it's any consoation, i couldn't race a stick either (never tried only drove stick a few times.)
...ed

 

Switch over to a carb setup and add a Perf RPM intake, a good carb of your choice, standard rebuilt HEI distrib, and a mild cam (210/220 ish duration). Do headers and a cat-back too. You'll be making a easy 240-250 hp w/ that.

Check out this LG4 buildup article for some numbers. I *think* you have higher compression than the LG4 to your benefit too (I can't remember anymore). Seems like the heads were the same between the TBI/LG4 so you're stuck there. As you see from this buildup depending on how wild you go w/ the cam and intake you can make 260-270ish w/ the stock heads. Definitely making 250ish easily attainable without going quite so big...

http://www.geocities.com/pilot19.geo/page1.jpg
http://www.geocities.com/pilot19.geo/page2.jpg
http://www.geocities.com/pilot19.geo/page3.jpg
http://www.geocities.com/pilot19.geo/page4.jpg
http://www.geocities.com/pilot19.geo/page5.jpg

My Vortec headed 350 gets about the same mileage as my 86 IROC and it's 305 TPI (few mods) and still passes the IM240 or whatever dyno emissions test w/ no emissions equipment other than the catco 3" cat ($99 in Summit, which you'll want to order when you order the headers and cat-back, so you go 3" all the way and ditch the TBI stock 2 1/2" or whatever it all is)

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Ray87Z
-Vortec headed 350.
86 IROC w/ a cammed 305 TPI.
Formerly Ray86IROC.
www.inter-scape.com/Ray

[This message has been edited by Ray87Z (edited February 13, 2001).]

 

The base engine for 85-87 IROCs is the LG4. The base engine for 88-89 IROCs is the TBI. The base engine for the 90-92 IROC/Z28's is the LB9. Only the 90 IROCs all had TPI. For 85-89 IROCs, TPI is the upgrade engine.

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West Coast GM Shootout 2001!
1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
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