I am beginng a project in which I plan to swap the 305 HO in my old 1984 Z28 with a new 350HO. The 350 that I bought can be seen here : http://www.crateenginedepot.com/sto...529-P824C0.aspx.

I plan on purchasing a new intake manifold ( vacuum leak) and possibly a carb if needed.

The car will be used on the street and must pass massachusetts emissions. Due to a low budget I would like to reuse what I can from the old 305.

Does anyone have tips or advice for this project?

Thanks,
Fred

 

The GMPP 350 HO motor won't pass emissions. It uses Vortec heads which have no exhaust crossover passages. Therefore, the intake manifold won't have an provision for an EGR valve (regardless of which intake you're looking at). No EGR valve means it won't pass a visual inspection and might fail the sniffer.

About the only truly safe choice in GM crate engines to replace an old 305 is the GMPP universal replacement 350 rated at 250-260HP (depnding on whose numbers you beleive). It's a modest compression, modest cammed 350 that will take literally EVERYTHING off your stock motor without modification. Trust me, it'll feel like you strapped a second engine under the hood compared to a worn-out old 305. Done this swap quite a few times. If you're really on a tight budget this is really hard to beat- $1300 complete, swap all your parts onto it.

One step up is the entry-level GMPP 290HP 350ci crate engine that is the same motor as above but with a little bit more cam in it. It's not so big a cam that it wouldn't pass a sniffer if tuned well.

Intakes that would be truly emission legal would be limited to an Edlebrock Performer intake with EGR provisions, or similar from another manufacturer. Or your stock intake, obviously.

 

GM also has a TBI vortec aluminum intake with EGR P/N 12496821. You can take the EGR flex pipe from a v6 to plumb the exhaust gases to the intake.

 

Whatever happened to the GM ZZ4 emissions legal package for the F-body? Do they still offer it? It was essentially everything you needed to convert a CLCC 305 car over to the 350 H.O. including an emissions sticker. Back in 1992 it was a $4500 package and even included suspension pieces.

Look around on the internet and you might be able to re-create the package. Essentially you would need an 305 H.O. carb, a knock sensor, a 305 H.O. chip for the CLCC computer, new distributor, and some emissions legal headers and cat-back such as the Hooker or Edelbrocks with A.I.R. tubes.
IIRC, in full emissions compliant trim, it was a mid-13 second capable engine package.

 

GM discontinued it a few years ago.

 

Yes, but I beleive you can still order the individual components by part number.