anybody have any suggestions for cranking out a little bit more power? I'm deffinately gonna do some exhaust mods (perhaps try to make it true-dual), but I'm concerned about losing gas mileage b/c it will be a daily driver. this place gave me a few things to think about:

http://www.inter-scape.com/ray/305buildup.htm

i'm kinda liking the vortec heads. i know that adding power will decrease mileage, but i'd like to get some stuff that won't really make my easy-foot driving suffer, but i know it'll drain it when i get on it. on that site i believe they claim to get 325hp(?) from their mods; how much gas mileage do you think that will get? i know i'd get more power from a 350cid, but i'm thinking that i could get decent power from a built 305 and get better mileage too. anybody wanna confirm that thought for me? i'm thinking that emissions will not be a problem for me in AL, but it will be a daily driver as i mentioned. i'm not sure if money will be a problem, but i'd still like to hear some ideas. i'm not really looking for a blower/nitrous setup yet; i'm kinda going for n/a for now. i'll probly keep it carbed as well.

also, i've been told that there is a forced air induction(?) kinda thing for my functional hood scoops; anybody know where i could find one?

one more thing: if i decide to get a blower, i'd wanna have an intake setup that would be as low profile as it could be. i.e., i dont want a stack poking out of my hood. even though that would be awesome, i'm too affraid someone will mess with it, as it will be a daily driver. any hood suggestions for that? is there a cowl induction type hood with the z-28 scoops anywhere?

i'd appreciate any thoughts/comments made. thanks.

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1984 Z-28, 305 4bbl, t-tops, K&N, Flowmaster 80 Series with 3" tips. I'm planning a massive modfest involving a new 350 engine w/ TPI. It's gonna be one gangsta of a street demon.

 

i wouldnt even bother with the 305, the 350 wont make all that much of a diffrence emissions wise that everyone says as long as its running correctly, a set of vortec heads on a 350 will be a good setup, get a mild cam, other little bolt ons and you'll be ready to go with no worrys from the smog man. also anything you do to add power that doesnt involve putting more gas into the engine will give you more power AND gasmilage, like exhaust, roller rockers, moving timing curves, etc are good examples, things like bigger cam, harder injectors and things like that will make the power more and will bring milage down slightly

 

dont waste the money on a 305 it will just blow up. save yur money and build a 327 or a 350

 

I've been asking myself and my friends the same questions for months. I have a 305 tpi. I recently put on a 3.23 posi-traction rear, u wouldn't think it would do much but i can feel a big difference and it doesn't effect my mileage that much. I have decided however to go with a 350. The gas mileage between 350 and 305 isn't that big of a difference and the 350 has a lot more potential for mods, it's not that the 305 is a bad engine or easily blown up, they'll take a beating, but the 350 is designed so much more effeciently

 

Maybe you guys should reread his topic?
He didnt ask if he should go to a 350 or stick with the 305. If your you 305 short motor is in good nick, stick with it.. Dont listen to these "350 is everything" guys
You'll have less weight to rotate as well in a 305.

 

I have had a 350 and yes it was much stronger than the stock block 305 that it replaced but it didn't get as good of gas milage. Now I have the LO3 back in with an LT4 cam and I cannot seem to get less than 20 mph with mixed hwy/street driving no matter how hard I run it. If you know what you're doing tuning it I'm sure the 350 could get better milage but that's my experience.

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91 RS 5.0 TBI....LT4 cam....Edelbrock headers....3"Dynomax exhaust....5spd.... 3.08.....Ultimate tbi....afpr...ZR 255-50's...Koni's

 

Dauntless,

I have an LG4 IROC. While I'm not a speed-demon by any stretch of the imagination, I have made some modifications to the car: Summit cam and double roller timing chain, Edelbrock intake, L69 dual snorkel with KN filter, tweeked carb (air valve tension and DR secondary metering rods with G hanger), high-flow cat and catback system, etc. Why did I throw these mods at a 305? I wanted a great daily driver to run a bit better. Gas mileage, by the way, on a recent 3,200 mile trip was 20 mph on I-80 where traffic averages 80, probably 24 overall, and I had one tankfull at 25.6--I must have been coming out of the mountains with a tailwind. Don't get caught up in the 350 vs 305 debate. Please yourself. It's your car.

JamesC

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[This message has been edited by JamesC (edited October 27, 2001).]

[This message has been edited by JamesC (edited October 27, 2001).]

 

I'd recommend staying away from the Vortecs. They may only be $435/pair, but you'll have to get an intake and self aligning rockers, another $200+. Then, you'll have to have them shaved to reduce the chambers to 58cc to keep your compression up. And, they have press-in rocker studs, while you're getting them shaved have them machined for screw-in studs.

By the time you're done, you'll have $900 in them. Instead, consider World S/R Torquer 305 heads - screw-in studs, don't need special rockers. They benefit from pocket porting, but that's something you can do yourself if you've got an air compressor.

Those heads, plus cam and exhaust upgrades, you'll up your power and retain streetabililty and economy. See sig for my work-in-progress.

This is all assuming your bottom end is sound. If not, forget it and go with the 350.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. 2-1/2" cat-back, ZZ4 intake, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (ported World 305 heads, Crane PowerMax cam, Hooker 2055 headers, 3" Catco cat & 3" catback, restalled TC, Spohn SFCs).
57 Bel Air, my 1st car. '66 396, 9.7 CR forged TRWs, Weiand Action+, Holley 750VS w/4150 conversion, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 600 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).

 

If you want 300 hp from your 305 you can do it with ported stock 4bll. heads[1.84/1.50] a weiand 8004 and a comp cam 268/454 or crane energizer 272/454 and flat top pistons. If you want more than that it gets exspenive so you'd be better off with a 350. I have a 305 .030 os/310 build as above but with 87 gm alum. heads 1.94/1.50 valves. Any sbc with enough cam will make a hp per cubic in. if the heads will flow enough. I have an article with 305/ 387 hp but it has huge heads for a 305.

 

how would roller rockers improve gas mileage? and for anybody who has a modded 350, what kind of mileage do you get? anybody have any suggestions for anything else i mentioned above?

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1984 Z-28, 305HO 4bbl, t-tops, K&N, Flowmaster 80 Series with 3" tips. Planning a massive modfest. It's gonna be one gangsta of a street demon.

 

also, any advantages to building a 327? how 'bout a ZZ4? the zz4 has loads of torque. any gas mileage estimates for these?

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1984 Z-28, 305HO 4bbl, t-tops, K&N, Flowmaster 80 Series with 3" tips. Planning a massive modfest. It's gonna be one gangsta of a street demon.

 

well, you could start with a set of 10.8 to 1 compression keith black pistons, total seal rings, and a balanced lower end. as for heads, port the stock one's, have screw in stud's installed, edelbrock torquer valve springs (good price), 3 angle valve grind, 1.5 ratio roller rockers, guideplates, and hardend pushrods. either port the stock intake and cut out about 2 inches of the center divider or use an edelbrock performer or weiand action plus. pick up a hypertech coil with some decent wires. a k&n extreme lid with an airpan would seal the carb to the hood so you could make your own ram air. that should pretty well get you a good daily driving 305 with gas milage in the very acceptable level.

 

Look for previous posts by RB83L69. He has a strong running L69 and offers loads of good info.

I'm going to agree with his statements as being the top three things to hold back performance on these cars:

1. Exhaust, headers and good 3" exh. No cat if not needed.

2. Install a better cam.

3. Better heads.


Done properly the gas milage will get better if anything. Depends on the cam chosen.


Good luck!

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91 RS 5.0 TBI....LT4 cam....Edelbrock headers....3"Dynomax exhaust....5spd.... 3.08.....Ultimate tbi....afpr...ZR 255-50's...Koni's