TBI Conversion

[KeyAir]

Hi Everyone!
I have a 1973 Chevy K10 Pickup with 350/350/NP205, that I'm restoring/converting into a Wilderness camper.

The original Quadrajet was giving me problems for years and a rebuild by an "Expert", made things worse.
I swapped on an Edelbrock, and that was its own nightmare.

Anyway, I have had TBI's on BBC's before and loved the way they ran and the reliability, so I thought a 350TBI or a MSD Atomic would make sense.
Reliability and parts availability would be a priority...
The Motor is a 350 4 bolt... maybe the the original, but was rebuilt sometime... Compression showed 160psi ish across all 8, so OK.

So, this week I picked up a used TBI, but I think mostly complete setup... for $150.... saved me spending a week at the Pick and Pull at least!
Its from a 350, so smaller bore unit, Intake manifold, ECU and harness, Dizzy, 2 coils, EGR, Fuel pump relay, and a bunch of parts that I recognize but need to verify what they are.

First surprise was the Intake... Its Aluminum, not cast Iron as the BBC units are... Is that normal?
I was planning to run a Edelbrock Performer Intake that I have on hand, with an adapter..
Is this stock intake good?
The ECU is stickered Service No. 16146299 AWLD.
My research here says its a 1992 305/350 ECU.

Any advice, input or comment to help me is welcome!

[trlrider]

To use the TBI intake on you SBC you will not to slightly ream out the middle bolt holes. They have a different angle then the ones on the end. I use old rocker balls and a slightly longer bolt. The rocker ball will self align to the intake for even pressure.

But using the Edelbock or any similar dual plane intake works as well with the TBI adapter.

Sounds like you pretty much rounded up everything! Did not see a O2 Sensor listed, you will need one, usually on the left exhaust pipe. If you are running stock manifolds, on the pipe about 2 inches from the flange. If you are running headers you will want a 3 wire heated O2 sensor, as the collectors are to far away from the head and you will have tuning issues.

I am pretty much doing the same thing. Swapping my nearly near 350SBC from my wrecked 1986 Blazer into my 1993 Suburban utilizing a adapter plate. Only real difference is a Gen1 motor going into a already TBI equipped truck.

[KeyAir]

Thanks for the input!
I did not see an O2 but, I have headers with dual exhaust and no H pipe, so 3 wire it will be.
Actually I have a pair of "727" ECM's to hand from from an "87 and '90 R20 454 suburban, and just read they are better supported and maybe work in this application?

[tayto]

I think you mean 747.727s were an underhood ECM on the TPI corvettes. As for intake, I would just run an adapter plate. GM actually used one on the 454 TBIs that still had a Qjet manifold. You can find them on ebay, kinda pricey now bit a factory piece nonetheless.

[dave w]

Gearhead-efi link for TBI computer 16146299: http://www.gearhead-efi.com/Fuel-Inj...Information-99

dave w

[KeyAir]

Thanks.
Yes, 747. I remembered wrong, lol.
Apologies in advance for my lack of knowledge and questions!
So, I have the factory aluminum intake, and an Edelbrock performer.
As its TQ/MPG I’m after in this mild setup what are people’s opinions on one vs the other?
The truck is pre-smog, so I can do what I want without worries here in CA... and it will still be cleaner than the carb.
Have a complete spare 454 TBI system on hand but assumed a small block setup would be better suited.
I built myself a Vapor Blast Cabinet last year, so whatever intake I use will be blasted and Cerakote’d.
Same for the TBI unit when I rebuild it.
Should I bother to to mill/smooth it?
Adjustable FPR?
Injector spacers etc?
Can you rebuild the injectors on these, or should I just replace?
If so, who does them best?
gotta figure out how to post pics here.

[dave w]

I like the Edelbrock intake vs. Factory Aluminum Intake.
Adjustable FPR, not necessary in my opinion.
GM Remanufacturing offers rebuilt TBI injectors: https://www.gbreman.com/products-all
Injector spacer, sure why not ... I'm neutral.

dave w

[dave w]

Thanks.
Yes, 747

Gearhead-efi link for ECM 1227747 information: http://www.gearhead-efi.com/Fuel-Inj...Information-42

dave w

[In-Tech]

As usual, Dave is correct, the adjustable FPR just leaves you options although not a repeatable one for others that just change the spring and tune accordingly. The TBI injectors don't have the same fate as injectors in the port because they don't see the "EGR" effect induced inside the intake manifold. Shoot they ARE 20 plus years old and everything tires of cycles, remans may flow correct on the flow bench but still fail after some cycles. The new crap seems to all come from China and results vary so I have no opinion. Even new AC delco seems to vary :( I generally use old stockers. Oh, as far as intake coating, make sure you don't coat or polish the inside of the intake manifold. That roughness and heat really helps with homogenization, but, the flow increase is only known at WOT and how much time do we really spend there vs part throttle driving. The 7747 computer is a start, if starting from scratch I would always start with a 7427. Much more powerful and faster datastream :)

[PlayingWithTBI]

In answer to one of your questions - yes the OE intake manifolds are aluminum. Another option for an ECM is the EBL Flash-II. It's pretty much plug and play with the wiring harness from the 7747, maybe one wire re-pin (IIRC) plus 3 wires for the Comms cable. Lot's of great support plus, it can learn/modify your VE tables automatically. You can get your Throttle Body rebuilt/replaced with flow matched injectors from a couple guys. Here's some links...
https://www.dynamicefi.com/EBL_Flash.php

http://www.rvmorsemachine.com/

https://www.ebay.com/str/sprperformance

[KeyAir]

Thanks guys!
The Cerakote is just a super thin clearcoat, purely to keep the finish good.
Let me look at the other ECUs I have and confirm.

I will dig into the info provided so i can understand better.

[trlrider]

Gearhead-efi link for TBI computer 16146299: http://www.gearhead-efi.com/Fuel-Inj...Information-99

dave w

[KeyAir]

Stripped and dry blasted the intake back to bare aluminum, still some details more detail to get before Im happy with it.
Interestingly, the EGR was already blocked off...
6BD9223C-C5B7-4323-B548-B4054DB200A7.jpg

82190024-0DFD-4239-841C-06BB2E0F665C.jpg

58DB7282-0C7F-4FA8-BA3C-0F2BF8DEEC9B.jpg

Then I set off, and stripped the TBI unit back to its bare components.


The whole thing was actually in nice shape, and the injectors look like new, so I will test them for function, and wait and see how they spray.
Only thing that puzzled me was 3 out of 4 of the vac post stubs were sealed off with silicon by the look, so I will have to clean that out!
I thought I would go full on, and check the throttle shaft wear, and 3 out of 4 of the shaft screws broke off despite me grinding the screw tips off...
Where are you guys getting replacements screws and rebuild gasket kits?
Any comment on how much wear is acceptable?

Into the Vapor Blaster the castings went, and they came up really nice.

B8359EE3-84F3-467F-895F-CBEADA6EE79E.jpg
CF6C92F6-E6AB-42F3-926B-34DA21B52BB9.jpg

[KeyAir]

I think these are good replacements...
https://www.grainger.com/product/GRA...D-Button-6EB95

[PlayingWithTBI]

I think these are good replacements...
https://www.grainger.com/product/GRA...D-Button-6EB95

IMHO, I don't know if I'd want to use steel screws in that application in case one disappears and starts bouncing around inside a cylinder. Years ago I lost a brass screw off the choke butterfly on my Plymouth GTX 440, couldn't find it but had no detrimental issues either.