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Tbi

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ecameron87

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Is it possible to install a TBI onto my stock motor? I have a '72 K5 with a GM Goodwrench crate 350 motor in it with an edelbrock intake manifold and a stock quadrajet carb. Can a TBI unit bolt up to this intake with an adapter? Do I need the computer and a fuel return line? O2 sensors?
Thanks
 
No, they take a different intake. And yes, you do need the return lines and a computer. People have put TBI in their vehicles here, and Im sure they will chime in. It does take a lot of work.

EDIT: Sorry, yes, you can get an adapter. I didnt see that in your question.
 
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Yes it will bolt up to your motor with the holley tbi adaptor plate, thats what I did. There is a little more to the swap though. You'll need the wiring harness, a electric fuel pump for tbi, o2 in the exhaust, ecom, the correct distributer, run new fuel lines, returns, vacumns and a few misc parts.
 
not to hijack... but to go from tbi to carb... what do i need to change? im going to carb cuz it will cost to much to gather the 350 tbi stuff for my new engine..
 
stockk5 said:
not to hijack... but to go from tbi to carb... what do i need to change? im going to carb cuz it will cost to much to gather the 350 tbi stuff for my new engine..
Click to expand...

????? If your going from TBI to carb you've got everything for tbi???? I think you'll have to change the intake because I don't know of an adaptor, need a carb, if your doing away with the ecm, you'll need a manual fuel pump, sending unit, HEI big distributer.
 
I converted my '72 Cheyenne/20 to TBI using a 454 TBI & Qjet adapter setup. Pics and information on my website www.speedyoldtruck.com

I'm currently selling the cheyenne, new truck ('71 K5 Blazer) is getting an LT1 intake for the current time...
 
For a lot less hassle, you could go with a holley projection system, but if you want to do a swap, I woudlget a harness aout of a 87 truck, as they are the simplest. You will need a TBI distributor, adapter plate, or get tbi manifold center holes (4) drilled out. I would also get new sensors. I got my harness out of a 91 sub and I had to get EVERYTHING. every wire that was in fron of the drivers seat, I got. TBI guage cluster, junction block, and of cousre ecm. You will have to either get stock manifolds or weld an O2 sensor bung in yours. Also, to get it to work properly with your system, you will need a custom chip, but it may work well enough stock.

In my opinion, it would be a lot less hassle to get a holley system because there will always be a bunch of stuff that needs to be fixed to get the stock harness to work. The holley system's ecm can programmed by yourself with little effort. I have not done it, but I havent heard any complaints.

Im sure there is somehting im leaving out but thats all I can remember right now.
 
The mother of all TBI knowledge. Read it before you do anything. One hell of a great siter for those of us running TBI engines, and/or wanting to swap over.

http://www.tbichips.com/truckmods.htm

Yes, you can run a TBI unit on a stock intake manifold with an adapter plate. The stock TBI intakes suck @ss. Also, there are mods you can do to the TBI unit itself to get more CFM. I plan on doing the 50mm bore, polishing, and shaving of the butterfly rod.
 
i only say that i wouldnt stay tbi cuz i have a 305 tbi set up right now.. the engine im getting has high intake manifold w/ holly carb on it. I cant afford all the new computer/other stuff for a 350 tbi... thats why i was gonna stay carb. but i guess if i have to buy new sending unit and all that either way i have to spend the money!
 
If you used your new intake the cost would be:

$47 for adaptor
$30 gaskets
$7 chip cost - some burn/program their own
or
$75 to $300 for someone else to burn it. Some CK5ers have the ability to burn chips..... Do a search.

Don't know about the difference in injectors (350vs305) but I just picked up a throttle body with injectors and sensors from this site for $20.

The sensors (o2,temp, knock, etc.) from you 305 should be the same as a 350.

So you could spend $200 on an intake and $400 on a carb, rewire your engine compartment, buy a fuel pump, and drop your tank and get a sending unit.
or
Use your tbi intake, get a new chip burnt and pickup some 350 injectors for around $100 and have a truck with better throttle response,no studdering at angles and better mpg. Just my .02c
 
Great information, guys. I would like to go fuel injection of some sort in the near future. I would like the most reliable setup possible which I hear is TBI. How reliable is the Holley Projection system? And how is it less hastle of an installation? It runs about $1000 correct?

Currently the Quadrajet runs pretty good. It does skip whenever I hit a good sized bump while offroad, and on steep hills it does surprisingly well. The only thing that bothers me about it is the lack of responce from the secondaries at WOT. Plus I have a hesitation at idle (Slight hiccup ever 5-10 seconds.) It goes away if I change the timing, but I keep the timing advanced because it performs much better. Is there a way to fix this hiccup without changing the timing? Vacuum advanced?

Anyway, I would like something that runs smoother and provides better MPG and performance. Is TBI the way to go, or the projection system? Maybe I aught to research this a bit more.
 
Well, I ended up going with the Holley Projection unit. It was really a painless installation. I can't believe how much of a difference it has made. Before it felt like a heavy Blazer, and now it feels light even after I just installed a roll cage at the same time. Throttle response is real quick and it feels powerfull throughout the whole throttle range. I don't know if gas mileage is better yet, but a do know that it has not gotton worse.
 
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