Someone over at www.67-72chevytrucks.com pointed me in the direction of this site...

Anyway. I want to get a fuel-injection setup for my truck (a 1970 GMC, with a 350/Vortec heads under the hood...possibly eventually a 383). Doing a bit of research, it seems that a TBI setup will not only be easier than a TPI to install, but be cheaper (no $300 Vortec baseplate) and higher performing (I do want to run it past 4800RPM).

So, what am I looking at to convert to TBI? My engine as it sits with a 750cfm Quadrajet is pushing about 250hp...the farthest I'll take it anytime soon is to about 350hp, maybe a little more (that would be a Comp Cams XE256H cam, headers, and a 383 bottom end). From what I can tell so far, I'd need a throttle body complete with the IAC and injectors, an electric fuel pump and return line, an adapter plate to bolt the throttle body to the Edelbrock Performer Vortec, an ECM, a chip programmer/eraser, and a computer-controlled HEI to replace the vacuum/mechanical HEI in it now.

Is there anything I'm forgetting? What sensors does the ECM need for a TBI - namely, would I need to rig up a speedometer setup for my 700R4 so I can use my mechanical speedo but send a signal to the ECM? What vehicles are good sources for easily reprogrammable computers / other parts?

Possibly most importantly...how much money would I be looking at spending?

 

you can grab pretty much everything you need form yoru local salvage yard really. just look for a 350 powered tbi vhicle adn start pulling everything. i have never grabbed a whole system form a yard, but i have heard that they usually charge between 150 and 200 to grab everything needed. you will jsut want to pop in a fresh O2 sensor and you shoudl be in pretty good shape.
i forget what year gm stopped using cable driven speedo's, but i seem to remeber them having a set up that was good for signal and for teh speedo. look under mid 80's period rear drive vehicles and see if you can find one. it woudl be a kinda oversized looking cable drive speedo set up.

good luck with your swap.

later
tim

 

I take it, then, that the TBI ECM does require the vehicle's speed?

 

He have to have the vehicles speed would he? That's only for the torque converter lockup and the speed limiter isn't it?

 

If that's true, then I don't need the speed to the ECM...I have the TCC controlled simply by a series of switches (4th gear, engine vacuum, brake light) and I certainly don't want / will encounter a speed limiter. I'd just as soon set the ECM up as if it was hooked into a car with a manual transmission, since I already rewired my 700R4 when I put it in to get it away from the computer-controlled version.

 

i don't think it will effect teh ecm too much, but it certainly helps when datalogging to compare air/fuel or blm to vehicle speed and throttle position.

later
tim