Can I do this?

[Unofficial]

I currently drive a 1987 R10 with a 305 TBI/700R4. I bought a 350 maybe a month or so ago, and it's coming back from getting bored out at the end of this week.

My question is: Would I be able to carb the 350? I've heard that since the throttle body is electronic, the transmission relies on the computer in some way when it comes to shifting. Would I be able to pull out the 305 TBI and drop in a 350 with a carb without any problems?

I appreciate it. 

[Fordeatinz71]

you could, but why?  if your TBI is working well, i'd use your current TBI.  it's more fuel efficient and you'll most likely get better performance.  but, if you're set on converting, here's the answer to your question...whoever told you the transmission was computer controlled didn't know GM trucks.  the transmissions were NOT computer controlled until 1993.  before that you had the standard 700R4 which had a TV (Throttle Valve) cable controlling the shift pressures.  so yes, you can run a carb'd motor.  my 1983 has a carb'd 305 and the exact same 700R4 you have...

[DnStClr]

Right. The 700R4 doesn't need a computer before 1993. But it should have a lockup torque converter.

[Fordeatinz71]

yea it will, my '83 has a lockup convertor. 

[VileZambonie]

Just change the injectors and the prom in the computer and leave it TBI

[Unofficial]

Just change the injectors and the prom in the computer and leave it TBI

That's another thing. I heard that I need to put in injectors from a 350. I can't use the ones from my 305 is what I've been told. My dad disagrees because the O2 sensor will tell the injectors how much fuel to use, and it doesn't matter where the injectors came from, but I want this done right. And what exactly do I have to do to the computer? Also, what exactly do I even have for a computer?

This is the reason my dad and I were deciding on whether or not to carb the 350, he's very familiar with tuning and working on carbs, while he's not very familiar with TBI. It's up to me though.

[Captkaos]

The ECM is the 747.  Most popular ECM in terms of people using them.  The injectors from the 305 will work but to get the most from the motor at full throttle you need bigger injectors.  An alternative is to raise you fuel pressure by making the regulator adjustable..
The O2 tells the ecm to change the fuel metering, but it is basing it on the tables for a 305 in the PROM  At WOT the computer isn't controlling much of anything.

There is NO way I would convert one back to a Carb.  You are talking 2 injectors and a gasket kit for the TBI and a GM PROM as opposed to converting the fuel lines to feed a carb, adding a regulator, removing all the wiring, buying a carb and distributor and a intake manifold. 

The injectors are $70 apiece and the PROM is about $100.

[comp]

The ECM is the 747.  Most popular ECM in terms of people using them.  The injectors from the 305 will work but to get the most from the motor at full throttle you need bigger injectors.  An alternative is to raise you fuel pressure by making the regulator adjustable..
The O2 tells the ecm to change the fuel metering, but it is basing it on the tables for a 305 in the PROM  At WOT the computer isn't controlling much of anything.

There is NO way I would convert one back to a Carb.  You are talking 2 injectors and a gasket kit for the TBI and a GM PROM as opposed to converting the fuel lines to feed a carb, adding a regulator, removing all the wiring, buying a carb and distributor and a intake manifold. 

The injectors are $70 apiece and the PROM is about $100.

will that 747 ecm work the 454 TB

[Captkaos]

Yes, the TB is the same other than the size of the bore.  That is the only difference.  The 747 was using on 2.8L also..  PROM control the amounts.

[Unofficial]

Ok thanks for the help. I'll stick with TBI. So where exactly is this "ECM" and "747"?

[Captkaos]

It is behind the glovebox above the AC unit.  If you take the glovebox off you are staring right at it.  The actual PN for the ECM is 1227747
It is the most popular ECM for "hacks" and has be extensively documented.
www.diy-efi.org/gmecm
http://www.diy-efi.org/twiki/bin/view/Gmecm/1227747