Napster134

Hello everyone, I got a stock 91 firebird with a 305 tbi l03 engine and an automatic transmission with an overdrive gear in it with 67k miles on the car my car was wrecked 3 times by the previous owners, it was salvaged and parked for a few years while my dad had been working on it when he bought it in 94 and couldnt work on it anymore when he started getting busy about 6 monthd ago i decided to go pick up the car from the storage and have been putting all my money into it ever since, i just recently painted it and the looks of the car are pretty much finishhed so now ive been thinking about more power for the engine, the only think ive done so far was install an open element intake and made a air box out of heat resistant bubble foil to enclose the element with the vent on my formula hood to try and get mostly cold air into the engine, i dont want to install non bolt on parts on my 305 because i know im going to swap it out for a 350 in the near future ive been doin reasearch and came to the conclusion of either the L05 (year 92-93 ) from the caprice police car and swaping on some vortec heads on it or just going for the full vortec 350 I havent done much research on the vortec engines but i can see everyone is talking about the heads although i know that there are probably more than one model of the vortec 350 I really want to get some more opinions and help from someone who know more about these type of things, since ive never done a project this big. One problem i do have is that i live in California where smog law are very restrictive, and i heard that the vortecs do not have egr valves, which im not sure but i think that would be a factor on wether or not i would smog since the orig. engine has an egr valve. Thanks for any help

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InfernalVortex

Yeah if you need to smog it you're pretty SOL on Vortecs.

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five7kid

Vortec heads were never certified for use in passenger cars.

Heads without the exhaust cross-over passages were certified in Vettes with aluminum heads and TPI, but not with any TBI system.

You can use a B-body LO5 system in a 3rd gen if you go through the "motor change" process. But, the only heads you can use on it are LO5 heads.

Atilla the Fun

Wrong wrong wrong! It's been done. Legally. And was documented. You'll need the GM Vortec TBI intake manifold, it's $370. You'll need to modify your exhaust system to run external EGR to the appropriate fitting on this intake manifold. Then you can be legal. It is possible.
But is it worth it? For the same final money, you can get heads that are aluminum and have an E.O. number. That'll save you about 50 pounds off the nose of a nose-heavy car.

five7kid

I'd want to see that documentation before committing to the project and get approval in writing from the motor change station. Nothing like spending $1k+ on a project, showing up at the inspector's station only to get thrown out on your ear.

Atilla the Fun

I'll get into my files tonight, but documentation aside, I was trying to convince the op that legality isn't the only issue, worth-it-ness is equally important. And at the cost of making the Vortecs legal, it's not worth it compared to buying legal aluminum heads.

Napster134

so i guess my vortec ideas r shattered lol,

well ok so then i guess im sticking with the l05, the aluminum e.o. heads sound like a good idea

unless i get any other ideas on which engine, the l05 seems like its probably the highest hp & torque engine that would work good for an even swap on my car,

i wanted to keep the engine tbi although i was maybe considering the l98 from the tpi formula but i still got to keep in mind my california restictions.

So far i guess its the l05 9c1 with aluminum heads ?!

Thanks for all the help and info

Atilla the Fun

the LO5 with legal aluminum heads is a good move either way, but if you're going to use TPI, then it's more about weight than flow. The TBI, with Edelbrock's intake manifold and Holley's 670 cfm TB, will make better use of the flow than stock TPI will, because stock TPI is all done by 4800 rpm, while the other is good past 5500.
I'll move the documentation issue to PMs so as to not hijack this thread. If five7kid wants to post what I find, that'll be in a new thread, I imagine.