I have already searched tons of old posts, but I still haven't determined which TBI to use when I convert my L03 to a 350 H.O. crate motor in the next few weeks. Here are the alternatives I've found: - Holley 670 cfm TBI - Factory GM 454 TBI (if you can find one) - Open the L03 TBI up to 48-mm and do the Ultimate TBI mods - Just install 350 injectors in the L03 TBI and do the Ultimate TBI mods I know that JPrevost and Z28 Boy have done this conversion and they both utilized the Holley TBI. However, some people seem to think it's not that great, the GM injectors are better, etc. Also, I'm trying to do this swap for the least amount of money. Any recommendations? Also, I'm guessing that the Edelbrock Performer Vortec intake manifold is the most popular choice for this swap; however, it seems that there have been problems with adapting the Edelbrock manifold to the L03 setup (coolant temp sensor location, throttle bracket, cruise control, etc.). I was just wondering if there was a better alternative out there now. Any help will be much appreciated...thanx

You will atleast need the holley for that engine. The injectors are fine since they redesigned them after people had problems.

Yeah, but wouldn't the flow come out about the same if I opened up my factory TBI to 48-mm (1.89") compared to the 2" bore in the Holley unit? I could add the GM 80-lb injectors for about $167 and have a comparable unit to the Holley, right? Just wonderin'...

No, the 2 inch bores will still outflow the 1.89 inches of the bored out unit. You could try it, but IMHO you would be better off with the holley unit.

I would guess that everybody is using the 5.7L V8 Holley TBI unit (Jeg's P/N 510-502-6)...is that the case?

http://www.jegs.com/cgi-bin/ncommerc...22&prmenbr=361

Another thing to consider when deciding on the size of the tbi is nitrous. If you ever plan of installing nitrous on your car there are only 2 sizes of plates available. One for the 1 11/16 unit and one for the 2 inch unit. On the HO 350 I would go with pretty larg injectors. Maybe 80 lb or so, but others who have done the swap could give you better advice.

I had 80lb injectors on my car, not good. Switched to 65lb, made a difference (for the better). If you switch to that 350 HO motor your going to need a chip (350 eprom), ESC module and a knock sensor.

Someone put a 454 in there F-Body and they needed the 80lb injectors. For that engine, 65lb are more likely the best bet. Unless you into burning your own eprom chips....

My injectors are flowing over 100#'s now, With the new pump i'm getting , I;m cranking them up to 115# or so.

Looks like there is currently a new 454 TBI on ebay at http://cgi.ebay.com/ebaymotors/ws/eB...ory=33614&rd=1 going for about $230 right now...probably should go for the Holley unit, though. Just out of curiosity, can anyone tell me how much they paid for a used 454 TBI?

Also, should I go with a Performer or a Performer RPM with my 350 HO swap? I wasnt' sure if I would have enough clearance with the stock hood and the RPM manifold. JPrevost/Z28 Boy/whoever - do you have any advice?

I've been shopping for a used one most of the winter. Used ones usually sell for about $150.

I paID $140 for mine off ebay, the place to get em' is http://www.car-part.com/ just search under the 3500 series truck, there is some for under $200 and a few priced right at $200.

I priced out a brand new one from GM and it lists for approx $267.
I can get it for between $230 and $240 which to me is pretty good considering that that most places will get $200 for them used. Now I do realize the GM units wont have the injectors or pod, but that doesnt matter to me since I have those items already. But a new one wont need to be rebuilt and doesnt run the risk of having worn throttle shaft bores.

Eprom burning and at least 65# injectors, good fuel pump (not stock), and a 2" bore TB. If you don't do that you won't be happy and you're better off with a carb. That's if you're trying to get all the power out of the motor. Others have been happy starving the engine for fuel....
The RPM manifold (air-gap too) will fit under the stock hood if you cut the underbracing and use a drop base air cleaner without the stock spacer. I had to modify the base of the air cleaner with a hammer to clear the electrical connectors for the IAC and TPS. I then had to cut out a super small section of the air cleaner to keep it sealing. Keep in mind I have poly motor mounts and the holley 1" adaptor plate. Every car is slightly different but all in all it didn't take more than an evening to get it to clear everything.
I've been busy with school and our formula team so I haven't had a chance to get out to the 1/4 mile. I also need to install a driveshaft safety loop before they let me in with slicks. It'll happen in a couple weeks when finals are done.
I'm running the holley 670 TB with a LOT of fuel pressure. 28psi to be exact. Since I'm into burning my own calibrations the car idles just fine and has no problem sitting at 550rpm. I don't usually let it idle down that low just because oil pressure gets too low but it sounds awesome with the borla uncapped .

What injectors and pump are you running on your car?

Uh oh sounds like I might be the black sheep of this family. I didn't use the holley or the stock gm unit. I used one from turbo city. They have a couple more mods than just the ultimate tbi mods. You can look them up on www.turbocity.com. I have the matched #61 injectors too. Car runs good. WOT runs a hair rich even. I use a air/fuel ration gauge to get an idea of what it's doing. I also used their afpr and I am only running around 13-14psi with the stock pump in the tank. The only drawback of this unit is that it has 1 13/16" holes instead of the 2" holes. It may make up for the 3/16" with the shaved butterfly bars though. Has anyone else used this setup?

Hey bulldog, I have a 1992 RS and I happen to be doing the same exact swap as you, mine will be done June28th. The damn motor is on backorder so I can't do it June 8th like I planned.

the 350 H.O. motor that I bought from Jegs has vortec heads, so I bought the Vortec TBI Manifold. The Vortec TBI manifold made by GMPP has the stock 1 1/16" bores...I also wondered about getting a bigger TBI, but the manifold will not allow me to do so unless I get the manifold bored out. Not something I want to do. I know 7-9psi with stock injectors was enough for my L03. If I need more gas, i'll install my JET APFR and turn it up accordingly. When it was mistakingly turned up all the way before and I drove it for a day or two, it literally sprayed carbon out of the tailpipes and I put the stock FPR back on...Just my experience. How much more fuel can the 350 HO take than the L03? Especially with TBI?

Let me know how things go if you plan on doing the swap before I do. I also posted in the transmission forum about the flexplate (I heard getting the flexplate off the original motor was a bitch plus I wanted new) so you might want to think about that too.

What other mods do you plan on doing while the swap is out? I'm buying complete MSD ignintion and flowtech headers/y-pipe and a better flex plate. The Vortec TBI manifold also has everything in the stock location minus the EGR, its moved forward to allow for the bigger plenum.

Good luck!

Glad to see I have a fellow "madman", Fredless (ha). Actually, I'm starting my swap on June 21st, but it will probably take a while to get everything completed. Fortunately, I have a friend who is letting me borrow his warehouse to do the swap, so it's not like I have to tie up my garage for the swap . Also, we have an extra car for the time being that I can use to go to work, which works out nicely.

I'm swapping both my 305 and my T5 manual tranny out for a 350 HO and a T56, so I don't have to worry about swapping my flywheel over. I'll be installing the flywheel that comes with the T56 changeover kit from Speed Automotive.

As for other mods, I already have SLP headers going to a 3" exhaust, so that's covered. I'm going to install an Edelbrock Performer RPM Air Gap intake manifold for the Vortec heads, along with a 454 TBI I bought from a junkyard. I think I'm going to replace the pickup coil on my factory HEI and reuse my Accel 300+ wires. I'm also trying to work in a new Goodmark cowl induction hood to make sure that I'll have ample clearance for the air cleaner assembly.

I plan on documenting my "swap experience" on my new web site at http://www13.brinkster.com/scbaeb/camaro/ if you're interested. I'll hopefully start updating it later this weekend.

Keep in touch and good luck with the swap

Thanks for the website man, I added to my favorites.

I'll be checking it often as my swap nears.

-Fred