TBI to carb process

[PiutePete]

Does anyone have good resources they trust that outlines the steps to swap from TBI to carb and from TBI to aftermarket (Sniper/pro-flow 4)?

 

[PiutePete]

Also, a step by step on the heated O2 sensor set up would greatly assist my research.

 

[AyWoSch Motors]

Does anyone have good resources they trust that outlines the steps to swap from TBI to carb and from TBI to aftermarket (Sniper/pro-flow 4)?

I was actually just going to swap my 87 from TBI to carburetor. Haven't started it yet, maybe next weekend..

 

[PiutePete]

I was actually just going to swap my 87 from TBI to carburetor. Haven't started it yet, maybe next weekend..

I would be very interested to follow along! Will you be posting your steps?

 

[yevgenievich]

TBI to carb is relatively simple. Remove TBi, add carb(adapt linkage correctly especially when 700r4 used), add fuel pressure regulator, replace distributor with hei. Plug ignition on power to the distributor. Use existing oil pressure switch to run the fuel pump, while also leaving the ecu in place to prime the pump on key on command. Or swap to different fuel pump method.
Intake manifold change or adapter used

 

[AyWoSch Motors]

TBI to carb is relatively simple. Remove TBi, add carb(adapt linkage correctly especially when 700r4 used), add fuel pressure regulator, replace distributor with hei. Plug ignition on power to the distributor. Use existing oil pressure switch to run the fuel pump, while also leaving the ecu in place to prime the pump on key on command. Or swap to different fuel pump method.
Intake manifold change or adapter used

Even easier than that. Bypass the whole electronic fuel pump system, add fuel pump push rod, mechanical pump on side of block, and change sending units to standard style..

Then new intake, new carburetor, HEI, done. And my truck is manual, so no trans kickdown to figure out.

I would be very interested to follow along! Will you be posting your steps?

Most likely, or at least before and afters

 

[PiutePete]

Even easier than that. Bypass the whole electronic fuel pump system, add fuel pump push rod, mechanical pump on side of block, and change sending units to standard style..

Then new intake, new carburetor, HEI, done. And my truck is manual, so no trans kickdown to figure out.

Most likely, or at least before and afters

I was under the impression that TBI blocks don't have a mech fuel pump provision. TBH I haven't even looked at my block yet, maybe that's just a BBC thing? Would then the cam not have a lobe on for pump as well? My truck is a manual as well. That's why I'm researching this modification. Also what about pulling fuel through the electric intake pumps? Will the mech pump do it? My truck has dual tanks, so the switching shouldn't pose an issue. What are you going to do ECM-wise? Gut it or trick it into running? Pull the bulb on SES and go? When you say change the sending units to standard style what do you mean? Sorry for the mass of questions, but this really interests me.

 

[PiutePete]

TBI to carb is relatively simple. Remove TBi, add carb(adapt linkage correctly especially when 700r4 used), add fuel pressure regulator, replace distributor with hei. Plug ignition on power to the distributor. Use existing oil pressure switch to run the fuel pump, while also leaving the ecu in place to prime the pump on key on command. Or swap to different fuel pump method.
Intake manifold change or adapter used

The parts swap out should be straight forward. It's the ECM and electronics that concern me and where I'd love some step by step or even video. I tried screwtube...the few I found, not sure I know enough to trust them.

 

[gmbellew]

why are you ditching the factory TBI?

 

[AyWoSch Motors]

I was under the impression that TBI blocks don't have a mech fuel pump provision. TBH I haven't even looked at my block yet, maybe that's just a BBC thing? Would then the cam not have a lobe on for pump as well? My truck is a manual as well. That's why I'm researching this modification. Also what about pulling fuel through the electric intake pumps? Will the mech pump do it? My truck has dual tanks, so the switching shouldn't pose an issue. What are you going to do ECM-wise? Gut it or trick it into running? Pull the bulb on SES and go? When you say change the sending units to standard style what do you mean? Sorry for the mass of questions, but this really interests me.

No, the TBI blocks have the the bolt face for the pump and a factory block off plate and the hole in the block for the pushrod. And the earlier TBI era blocks still used a cam shaft that has the fuel pump lobe they just wernt used. Up to about mid year 1994 still had the lobe. You'll just need to find a pushrod from another small block. As far as I know they're all the same
I have no idea about BBC I'm talking SBC. I could ask my friend who has 2 90s big blocks.
As far as the sender units, what I meant by standard is the older mechanical pump style. A mech pump wont pull threw the electric pump, and if you remove the electric pump itll work fine, but the pickup tube wont reach the bottom of the tank, and wont have a sock. You'll need the older sender units or modify what you have.
The ECM im just going to leave there, unless someone wants to. Either just unplug it, or leave it as is and just let it have a panic attack, haha. It doesnt control anything I cant bypass, except maybe the gauges, but i can swap those out for an older full mechanical gauge set.
You'll have to put an 4 pin module HEI in it as well, that way the ignition system is a stand alone system. It only needs one power source, just needs a key on power.

As far as I know that's all you'll need, but I won't know until I get there.

 

[PiutePete]

Lots of good info. I'll double check in my fuel pump provision this weekend. I read in another forum you can pull the pump from the TBI sending unit and rig in a solid fuel line with the stock sock. Don't know if this is true but if I have to drop the tanks I'll be looking seriously at this.

No, the TBI blocks have the the bolt face for the pump and a factory block off plate and the hole in the block for the pushrod. And the earlier TBI era blocks still used a cam shaft that has the fuel pump lobe they just wernt used. Up to about mid year 1994 still had the lobe. You'll just need to find a pushrod from another small block. As far as I know they're all the same
I have no idea about BBC I'm talking SBC. I could ask my friend who has 2 90s big blocks.
As far as the sender units, what I meant by standard is the older mechanical pump style. A mech pump wont pull threw the electric pump, and if you remove the electric pump itll work fine, but the pickup tube wont reach the bottom of the tank, and wont have a sock. You'll need the older sender units or modify what you have.
The ECM im just going to leave there, unless someone wants to. Either just unplug it, or leave it as is and just let it have a panic attack, haha. It doesnt control anything I cant bypass, except maybe the gauges, but i can swap those out for an older full mechanical gauge set.
You'll have to put an 4 pin module HEI in it as well, that way the ignition system is a stand alone system. It only needs one power source, just needs a key on power.

As far as I know that's all you'll need, but I won't know until I get there.

 

[PiutePete]

why are you ditching the factory TBI?

I haven't fully decided yet. The truck is a 1 ton dually and I know with very little I can get the Tq/Hp way better than the stock. My main concern is out pacing the 650ish cfm TBI. I am not against the idea of retaining TBI or EFI, however the idea is now that it's near the end of it's service life for the 454, I am exploring options to get the maximum reliable Tq for the amount of fuel going thru it. I have looked at the Sniper w/850 CFM and the Proflow with 1000 CFM, though the makes make it seem easy, it's the Stock ECM work arounds that aren't well explained. I did read about a dual TBI custom intake and that falls into the ECM area again.

 

[AyWoSch Motors]

Lots of good info. I'll double check in my fuel pump provision this weekend. I read in another forum you can pull the pump from the TBI sending unit and rig in a solid fuel line with the stock sock. Don't know if this is true but if I have to drop the tanks I'll be looking seriously at this.

That sounds like it could work. If your crafty you could braise a extension onto the sender unit to make it reach the bottom, and flare the end to accept some form of sock.
Luckily I have a dual tank parts truck frame with 2 good older sender units, and the truck that has the TBI has a flat bed that is tall enough that i can get the sender units out without pulling the bed, I can sit on a milk crate and do all the work haha.

 

[Memaloose]

The last TBI to carb I did was on an '88 Dodge W-150, 318, 4 speed manual. 1st year for TBI. I had endless problems with the TBI (intermittant fuel/ignition problems) so switched to a 2 bbl carb. I realize it's no GM but still, almost the same. No more electronic problems!

 

[AyWoSch Motors]

I haven't fully decided yet. The truck is a 1 ton dually and I know with very little I can get the Tq/Hp way better than the stock. My main concern is out pacing the 650ish cfm TBI. I am not against the idea of retaining TBI or EFI, however the idea is now that it's near the end of it's service life for the 454, I am exploring options to get the maximum reliable Tq for the amount of fuel going thru it. I have looked at the Sniper w/850 CFM and the Proflow with 1000 CFM, though the makes make it seem easy, it's the Stock ECM work arounds that aren't well explained. I did read about a dual TBI custom intake and that falls into the ECM area again.

Oh yours is big block, didn know that. What year?
If its 87 or 88, you might be lucky enough to have a carburetor spread bore 4 bbl intake with a factory adapter. My buddy's 88 454 had one of those. Thatd make swapping to carb easier.

As far as swapping to better EFi, I'd suggest maybe look into a late model BBC vortec setup (96-00). Stock parts, easy to find, bolt on, great torque, great power, with okayish mileage, and pretty cheap if you get a junkyard setup. And I'm pretty sure you could either get a custom wiring harness or just the computer from a GMT400 and make it work.