I'm looking at swapping the 335/350 Chev crate motor into my 85 IROC as an inexpensive way to gain a bunch of power. I'm running the 305 HO (Carburetor) and a 5 spd. My plan is for the 350 with a dual plane intake, Holley emissions carb, and headers. Being in California, I'll need to keep all the emissions stuff hooked up. I know I'll need a new chip. Is there anything else I should be alert for?

 

the Vortec heads have no EGR if that is the crate engine you are looking at. To be 100% legal you would need a carb legal intake like a Performer and heads with EGR. such as the TBI heads or some aluminum heads. The 23* trick flows are $850 and 50 state legal.

------------------
-Tas
'89 Formula WS-6

305, TBI, auto, 14x3 chrome flat based open element with K&N, Milodon 160* thermo, functional Formula hood, cross-flow Flowmaster, '99z28 rear pipes and tips....

To be installed eventually far far far into the future: Yours if the price is right and I don't have to ship :
Hooker 1-5/8" 50 state legal headers, Dynomax 3" I pipe (PN 44063 and 43248), Catco 3" cat, and injector spacer.

Super GRK_Taz World
F-Body Dual Exaust
EFI & Intake Options
AOL IM: superGRtaz

 

Thanks. After accounting for the extra $ for the heads, the zz4 isn't that much more. Does anybody know anything about this swap?

 

Just to be clear, you are talking about the 350HO/330 HP, correct? If so, it has the aforementioned Vortec heads with no exhaust cross-over. The Vortec Q-jet EGR manifold requires plumbing exhaust gases up to the intake.

The ZZ4 has exactly the same problem - no exhaust cross-over passages. The solution is the same - plumb exhaust up to the intake. That's what GM does with their "HO 350 Camaro Conversion Kit", which uses the ZZ4 for the base engine.

I have yet to hear of anyone doing a 350 HO Vortec swap and passing CA or other strict emissions inspection/testing. Doesn't mean it can't be done (and I'm not talking about slipping the inspector a few bills).

------------------
82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. Cat-back from '91 GTA, ZZ3 intake, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/'87 LB9 block, ZZ3 cam, ported World 305 heads, Hooker headers & y-pipe, 3" Catco cat & 3" cat-back, Spohn SFCs).
57 Bel Air, my 1st car. '66 396, 9.7 CR forged TRWs, Weiand Action+, Holley 750 VS, 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).

 

According to gmpartsdirect customer service, the zz4 uses a removable block off plate for the EGR connection. Sounds like it should work?

 

The ZZ4 heads (same as aluminum Vette heads) have no crossover passage. Remember that, because stock engines with iron heads have that passage and use it as the source for EGR exhaust gas.

The ZZ4 intake manifold has two bosses on the passenger side of the carb mount: one is directly in the exhaust crossover passage of the intake and is of the type that was used for hot gas type chokes in the '70's; the other is the mount for the EGR valve (the valve allows gases to flow from the exhaust crossover to the induction flow when open). The intake comes with a plate on both bosses (that's the removeable part). What they do for the HO 350 Conversion Kit is to take off the plates, hook up a tube from the passenger side exhaust manifold to that hot air choke boss to supply exhaust gas up to the passage in the intake manifold, and mount an EGR valve on it's boss. Then, it will work like the original factory setup (Vette TPI engines work in a similar manner).

The ZZ4 crate engine comes with the mounting boss in the exhaust manifold, but from what I understand it does not have the tube to go between the exhaust and intake. The conversion kit does have this tube, however.

So, it's not just a matter of unbolting a plate or two and everything works. There's a lot more to it than that.

 

Well, it looks like I'm back to the drawing board...
Thanks.

 

Darn, I LOVE living in Kansas. NO EMISSIONS TESTING!!! Now for the real reason for my post. Why not buildup that already emissions legal 305? Bore it, maybe even stroke it, buy some 50 state legal heads, intake, carb. and you're good to go...

 

Because there's no substitute for cubic inches... However, I am going to bite the bullet and shell out good bucks for a junkyard 350 from the mid-eighties, tap my heels three times, and build from there.

 

It's time to return to first principles:

1) "Inexpensive" and "bunch of power" used in the same sentence is called an "oxymoron".
2) You've got a T5, which is strained by a 305. Unless you go auto, "a bunch of power" is going to require "a bunch of money" for a manual transmission that will handle it.
3) What you call a "Holley emissions carb" is NOT emissions legal on your car! The only carb that is legal is a CC carb, or you can convert to a later FI system (with all that went on the later year system cars - bye-bye inexpensive).

You can get very good power gains with emissions-legal 305 parts: Comp computer cam, the headers you mentioned, an EGR aftermarket manifold or GMPP intake, high-flow cat & catback. And, one of the bigest helpers, World Products S/R Torquer 305 heads. You already have the right air cleaner. All of that will cost you less than the basic 350HO crate engine, and you may not even have to re-chip (although that would probably help). It might not have quite as much power as the 350HO, but it will certainly be respectible and will maintain emissions visual & sniffer legality through it all.

I'll do part of my sig again so you don't have to scroll up to see why I say all this. The "work in progress" part is running me right at $2000 (including the intake I installed already on the LG4 and the SFC's, gaskets, oil pump, die grinder, porting kit, and a torque converter that I didn't mention; but not including the time to do the porting and assembling that I haven't seemed to amass this summer). Dyno 2000 says right at 330 hp (what a coincidence).

------------------
82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. Cat-back from '91 GTA, ZZ3 intake, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/'87 LB9 block, ZZ3 cam, ported World 305 heads, Hooker headers & y-pipe, 3" Catco cat & 3" cat-back, Spohn SFCs).

[This message has been edited by five7kid (edited September 05, 2001).]

 

five7kid: How much of your new LG4 setup will work with my 305 TPI plumbing? Cam, World 305 heads, headers, catback all should be fine, but would I simply have to port my plenum to increase air flow (instead of your zz3 intake)? Still need a 58 throttlebody, so you think? And what's the detail specs on that cam? Thanks!

------------------
88 Formula, 305 TPI
MSD Coil, wires
Accel distr cap
K&N filter, holes in cannister
Monaco seats

 

It should all work. A 52mm TB should be fine, although you may get by with the stock unit and ported plenum & base. Shorter runners should be used to raise the RPM range of the induction up to the range of the cam.

The ZZ3/ZZ4 cam specs are:
208/221 duration @ 0.050"; .474/.510 lift, lobe sep 112 degrees.

If you go with the World heads and that cam, be sure to upgrade the springs. I wrote World and told them what I had planned and asked if they had any recommendations for clean-up. The said the instructions that come with the Standard Abrasives kit are good, but the bowl area is basically what will give the greatest gains. Most mag articles that I've seen do comparisons with these heads vs. factory have them bowl blended first. World also recommended at least 2000 rpm stall (I'm going for 2200).