The more I've been thinking about long-term plans for my '91, the more I believe I'll be doing an engine swap down the road. The 305 runs great, so I want to keep it for awhile...however I know it isn't going to give me the grunt I really want, and I don't think I want a modded engine built by a local shop that may give me issues. A crate motor seems to be the way to go, as I will not be doing this myself (I have neither the time, the skill nor the tools, despite the fact I'd love to do this myself!)

With that being said, it seems to me a ZZ4 might make an ideal choice...then I can leave the LO3 on an engine stand for eternity, or until I want to make the car stock again (with this being my summer fun cruiser, and not a trailer queen, I may never care, but who knows...). I imagine because a ZZ4 is meant for a carb, there is no reason why TBI cannot be adapted, correct? I imagine I could use my stock wiring harness (easing installation for the shop doing this), but I would need all the parts talked about in the 305 to 350 swap...

Out of curiosity, has anyone ever done this? I'm basically looking for the power of an LT1 swap, with nearly the MPG, without the hassle of adapting parts, as I won't be doing this myself. This seems like an interesting option. And yes, a T-56 and some rear gears would be part of this too!

 

The 305 to 350 thread is a good place to start, but you need to do a lot more research to make TBI work on a 430hp engine.

If it's not obvious to you now, let me make it very clear. There is NO way TBI will work on this engine without you learning to tune the ECM yourself, or spending a wad of money having some one else dyno tune it for you. Tuning will trully be the key to this swap making it out of the driveway or whatever shop that installs it. My suggestion would be to get the tuning equipment now and learn on your stock motor and then when you feel comfortable make the swap.

TBI will support this kind of power, but you'll need a 454 TB and 80 or 90 lb/hr injectors that most of those TB's had. You'll still need to increase the fuel pressure by quite a bit to support this power level.

 

ZZ4 is rated at 355hp. The rest I agree with, 90lb injectors at about 16psi should do fine. Tuning is a must, but should not be that difficult.

 

ahhh, sorry got confused with the zz430

 

Yeah, I'm not thinking about going as crazy as the ZZ430, but now that you mentioned it...

I know chip burning will be crucial, and I currently know nothing about it. I'm going to start seeing what I can pick up on the DIY board, and go from there. Apparently I can do a lot with the current setup the way it is, I just don't know where to start. My biggest question was on the injectors, so thanks for that...

Again, does anyone know anyone who has ever done this?

 

So I take it no one has ever done this? Sorry to drag back up my 4 month old post, but I met someone who is very knowledgable on swapping a third gen engine, and he said his boss (owner of a local garage) has a lot of tuning experience from tuning a 355 TBI in an old C1500 he had...the guy claims his boss would be able to burn a chip for me very easily, as the ZZ4 is not an overly wild motor.

I'm getting the itch to start collecting parts...any help is appreciated.

 

The ZZ4 heads are the same as the Corvette aluminum heads. They dont have EGR passages, and I dont know of any TBI intake manifolds that have the external EGR hookup like the TPI Corvettes do. That'll be a problem if you have to pass an emissions check. Also those heads have the older style intake bolt pattern, and all the TBI intakes I know of have the newer intake bolt pattern. Lastly, those heads are missing one accessory bolt hole for the serpentine bracket system. You'll have to carefully drill and tap it.

 

I mentioned it months ago when you were asking. At the time I had a 350 with a ZZ4 cam and heavily ported 081 TPI heads. Was making around 375 HP to the crankshaft. Was running an untouched Marine TBI unit and my own tuning.

EDIT- Several of the TBI members here at TGO are running ZZ4 cams in their 305. I think one even has the aluminum heads from the ZZ4 on his 305 TBI. It is entirely possible to run that engine on TBI.

I also found a couple of trucks that were running TBI setups on ZZ4s for off-road use. I cannot promise you on how they ran or if they got anything near what the ZZ4 should have for power.

http://jeepnut.net/_wsn/page2.html

http://jeepnut.net/_wsn/page4.html

Finally GMs own TBI Marine engine was up to 330-335 HP with Vortec heads, a highrise dual plane manifold, and a cam that only had 191/196* @ .050" duration (we in the car world know it as the HT383/RamJet cam). The engine had a 2" bore TBI unit on a high-rise carb manifold. The 2" TBI ran at 28 psi and had either 46# or 55# injectors in it, for either 73 or 88 lbs/hr worth of fuel. The aluminum L98 head version came in at 280-315 HP and ran the 46# injectors. The Vortec head version was 330-335 HP and had 55# injectors.

 

I thought that the Ramjet/HT383 cam had 10 deg more duartion on I/E, and that the 191/196 was the Vortec/B-body LT1 cam.

 

You are right that is the B-Car/Vortec truck cam. The Ramjet is 196/201 @ .050 with 1.6:1 rockers. It is still a tiny cam with only .431/.451" lift with 1.6:1 rockers.