BLUE92RS

What is the best way to get more horsepower out of the 305 TBI??? It only has 170 and that just isn't enough. Should i just get a new engine like the 330 carborated engine for chevy. Any enough would help and if you now where you can get cheap engines let me know please. Thanks.

89BlwnRs

You can still make power with the 305, but it starts out with two main disadvantages. Number one is the bore. The 305s bore is smaller than the 4" bore found on Chevy 350s and Ford 302s. This limits valve size and thus limits flow into the cylinder. The second downfall is simply displacement. Although superior in 3 measely cubes to the Ford, it's 45 short of the 350.

In short it's best to go with a bigger engine and a bigger bore. But if you want to stick with the 305 you can and still make respectable horsepower.

Unfortunately with the stock bottom end, there are only 2 real head choices available. The L98 Corvette heads are an excellent choice but lack EGR compatibility, and even so will need to be machined to provide the correct compression. World Products (www.worldcastings.com) also makes heads built for 305s, and these will need to be machined a little too to keep the stock compression ratio. These heads are 50 state street legal and come assembled for somewhere in the ball park of $800.

Any healthy hydraulic roller cam will do and the general consenus is that the TBI intakes out there suck. So going to a carb intake with a TBI adapter seems to be a good idea.

Then strap on headers which are made for our car, a better cat, and a cat-back and the car should be approaching 275 HP.

As far as cheap street legal engines go, maybe try speedomotive. They had a 400 hp 383 engine built for around $2500-3000. They're in California, but they said they ship anywhere for like $150 or something. Check them out on the web. GMPP also makes a bunch of crate motors, of which none are street legal for our cars.

Hope this helps,

Jason

91Bird305

I started out with little things like pullies and a tbi spacer, but when I started getting into higer gear ratio's and headers and exaust it really helped my 305. Now with all the mods I have done in my sig the car really hauls ***** for a 305 w/o inner work done (heads,cam,intake). If anything I would work on your 305 and do mods that swap onto a 350. That way when u start to learn how to work with our chevy engines you will be able to swap everything u learned and did with your 305 onto a bigger SBC, like a 350,383 or bigger. This is what I am doing now. I am going with the ZZ4 but there are plenty of great engines out there like 89BlownRS said. Just have to do a little bit of shoppin and see what you can find. But I highly recommend working on your 305 first so u can learn, then move on to the next step. You won't waste any money this way either, cause most of the mods you do to your 305 (headers,spacer,element,pulleys, etc.) will be able to swap onto the 350. Have fun and if you ever run into trouble always check back here. Someone will most likely have an anweser for ya.

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Eric Natzke
91 Firebird 305 TBI (ZZ4 summer of "01")
ASCD Ram Air Hood-3" custom exaust-Flowmaster 80 Series-No Cat-Edelbrock TES Headers (coated)-March Pulleys-TBI Spacer-K&N Open ELement-TransGo Shift Kit-B&M Supercooler 28,000 GVW-Hypertech Thermomaster-160 Stat-3:42 GM Gears-Auburn Posi Unit-Edlebrock Strut Tower Brace-MSD Superconducters-Accel Cap & Rotor
-Rapidfire Plugs-265/50/R15 Tires-Emmison's all Gone

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