Dump EFI for Carburetor?

[Sptwall]

'97 Tahoe, 2 door, 4x4, 5.7L Vortec stock motor, 165K miles.

Hello, fellow OBS heap lovers,
Like everyone else here, my rig is aging and requiring lots of hoses, sensors, wires/ connectors, and components be replaced...

I'm old school and still love the simplicity of carbs over EFI and all its BS sensors and attendant problems. So, when I change the intake manifold gaskets, I thought, why not ditch all that EFI crap and put in a new Edlebrock Performer manifold and carb setup?

Watched many YouTube ya'hoos pontificate on this subject. Most agree that they are happy with the change out. Problem, there is much conflicting info on revisions to wiring to get the computer to work correctly. The biggest issue being the shift control of GM's electronic tyranny...

I am aware there needs to be a Throttle Position Sensor on the carb. But, do I need the $700.00 tyranny control box or just alter certain sensor wires? Please advise if you have any "first hand" knowledge to impart. It would be greatly appreciated!

 

[tom3]

Too bad it isn't a five speed manual tranny. Carb and a vacuum advance distributor and you'd be in business.

 

[OR VietVet]

I grew up in the industry and learned on points and condenser, carburetor and distributor cap and rotor. I will take EFI any day.

 

[Hoesgottaeat2]

Why not throw a 4-speed in it while you're at it and make the old school transition complete?

 

[Sptwall]

Well, guys, thanks for the laugh responses! However, I was hoping for some actual information, specific to the conversion...
I'm just an OR RN, not a auto technician. I could really use some first hand knowledge. FYI, the HEI distributor you replace the stock one with, ain't got no points/ condensor. I want to go old school, not ancient.

 

[B-train]

You would need the trans controller for sure. The electronically controlled transmissions use all kinds of feedback and calculations from the engine sensors - throttle position, MAF, MAP, rpm, etc. It's not just a make the motor run and the trans will follow. To do that, you'd have to go back to a 700r4 with the throttle cable pressure advance as your only adjustment.

Personally I think carburetors are a waste of time, finicky, and just too ancient to make sense in a daily driver anymore. EFI adjusts to all conditions without you having to remember to pump it twice to set the choke, then pump it to get off high idle when it's cold, etc, etc, etc...

If you are in the PNW, then you have a rust free rig that is totally worth just replacing what was designed and engineered for your truck. It's lasted this long, so replace with all OEM and get another 165k out of it.

I'm not trying to sound judgemental or mean, just years of experience coming out.

 

[Sptwall]

Why not throw a 4-speed in it while you're at it and make the old school transition complete?

You would need the trans controller for sure. The electronically controlled transmissions use all kinds of feedback and calculations from the engine sensors - throttle position, MAF, MAP, rpm, etc. It's not just a make the motor run and the trans will follow. To do that, you'd have to go back to a 700r4 with the throttle cable pressure advance as your only adjustment.

Personally I think carburetors are a waste of time, finicky, and just too ancient to make sense in a daily driver anymore. EFI adjusts to all conditions without you having to remember to pump it twice to set the choke, then pump it to get off high idle when it's cold, etc, etc, etc...

If you are in the PNW, then you have a rust free rig that is

You would need the trans controller for sure. The electronically controlled transmissions use all kinds of feedback and calculations from the engine sensors - throttle position, MAF, MAP, rpm, etc. It's not just a make the motor run and the trans will follow. To do that, you'd have to go back to a 700r4 with the throttle cable pressure advance as your only adjustment.

Personally I think carburetors are a waste of time, finicky, and just too ancient to make sense in a daily driver anymore. EFI adjusts to all conditions without you having to remember to pump it twice to set the choke, then pump it to get off high idle when it's cold, etc, etc, etc...

If you are in the PNW, then you have a rust free rig that is totally worth just replacing what was designed and engineered for your truck. It's lasted this long, so replace with all OEM and get another 165k out of it.

I'm not trying to sound judgemental or mean, just years of experience coming out.

"B" thanks for input. You made several good points. However, the feedback on Edlebrock's newer EVS2 carb is generally good. Electric choke, annular atomization, and pump customization have all but minimized old carb design flaws.

Several YouTube folks inform that the electronic trannies only need the feedback signal from the Crank Position Sensor (splice in from HEI distributor's RPM port and an aftermarket Throttle Position Sensor added to the carb.

If this is all true, then ridding the engine of all those other sensors would be great, provided the post carb swap yields performance somewhat on par with the EFI system.

Would really appreciate input from anyone that has actually made the switch.

 

[Eman85]

Your truck do what you want. Much better to keep the EFI and ignition you have.

 

[Sptwall]

Your truck do what you want. Much better to keep the EFI and ignition you have.

Yes, Eman85, it is my truck, but I don't really know what I want. That's why I am trying to get some info to base my decision on.

I do appreciate all of youll's opinions. Thus far the concensus seems to be, "Keep the EFI"..
Need a carburetor lover to weigh in here, hahA.

 

[OR VietVet]

99.9% of members here run EFI and when is running correctly, the advantages far outweigh what a carb will do. Because of that, you MAY find someone here that has switched, like you are thinking of doing, but you may have a long wait before they find this thread.

 

[exp500]

And then you have the Q-jet vs Holley controversies. I personally liked and used and rebuilt many Qjets, and still service a few. Parts are getting harder and harder to find, and expensive compared to years ago.
Just like long ago, the parts sellers swear it's easy and will run perfect right out of the box. As long as you are prepared for a one year project Go for it!
Your choice of carb/ dist/intake/Trans box should include A 7r4 trans. Or you could
Consider keeping stock computer for trans and other electrics, unless you wish to rewire the whole truck. For instance brake pedal interlock.
We will gladly offer help on your conversion, just realize it's neither cheap or easy.

 

[Sptwall]

OK OK, I am convinced! I will keep the EFI, really. So, does anyone have recommendations on what sensors and other parts that should get routinely replaced related to the EFI system with 165K miles? Also, is it time to replace the injectors or just "clean them"?

I appreciate any advice as I currently am still in love with my Tahoe and would like to keep her awhile.

 

[B-train]

Realistically, if a sensor isn't giving you a problem, leave it be. At 165k, I would do belt, hoses, coolant, driveline service, tune-up, etc for good maintenance and longevity. The fuel system on that has 8 spider injectors - again, if they are working, then I wouldn't worry about it. It is an easy enough job though. I would run a good fuel system cleaner if you want piece of mind - Techron, etc. I've also just ran 1/2 qt of ATF in the tank as a cleaner/lubricant for injectors for many years without one issue (actually solved a few that way).

IF you are looking for a project and money to spend, then go after all the sensors on the motor, but be advised some will require a coolant change, others a relearn process, etc. I wouldn't personally open up the can with a spring snake in it if I didn't have to.

Glad to hear you see the benefits of EFI over carbs. I understand your initial desire for it, but find an old truck or car and get your feet wet there with that idea, one that won't have the potential to be a daily headache

 

[Eman85]

I like carburetors, I run them on my drag car. If I had the money I would probably like to try EFI on it. The truck that tows it to the track has EFI. I spent a lot of hours repairing and rebuilding carburetors over the years, Many under warranty when I was a dealer tech. Carburetors reached their limits back in the 70's but they kept whipping that horse until the 80's.
As far as replacing parts for what ifs chances are whatever you buy has a good chance of causing you a problem you didn't have before you replaced it. Buy an inexpensive scan tool like an Autel so you can learn and diagnose instead of changing parts.

 

[Sptwall]

I like carburetors, I run them on my drag car. If I had the money I would probably like to try EFI on it. The truck that tows it to the track has EFI. I spent a lot of hours repairing and rebuilding carburetors over the years, Many under warranty when I was a dealer tech. Carburetors reached their limits back in the 70's but they kept whipping that horse until the 80's.
As far as replacing parts for what ifs chances are whatever you buy has a good chance of causing you a problem you didn't have before you replaced it. Buy an inexpensive scan tool like an Autel so you can learn and diagnose instead of changing parts.

Big thanks for all that maintenance information! So, rather than throwing cash at the fuel delivery system and related sensors, I will go the intelligent route and replace when necessary, using a scanner for guidance.

I've already replaced the heating system components and won't even go into the hell I went through with GM's wonderful "quick-diconnect" fitting on the intake manifold. Still have to replace all 3 HVAC vent/ blend door actuators. Next weekend is replacing the multi-function switch on the steering column (thank you YouTube).

The suspension and driveline systems are areas I have zero knowledge. I bought this truck online, sight unseen, from CO. Had it shipped to KY. It has 9" of total lift, 6" suspension ( ProComp) and 3" body lift. This was much more alteration than I thought it had. I'm sure much of the changed geometry is stressing the aforementioned systems. On a positive note, it rides and steers well without any mystery sounds. I will never buy another vehicle online again without an in-person inspection...

Overall, the engine runs strong and doesn't burn a drop of oil. Plugs were all looked like they should (BTrain was right, it needed that tune-up as cap/rotor wore slap out). It all the ancillary systems in the truck that are worn out or broken.

Thanks to all for taking time and providing advice. I have always found if you shut your mouth, open your ears, and actually listen to the words of wisdom, you become smarter...

 

[Mater]

as long as you have a RPM signal, map signal, engine coolant temp, and TPS. the computer can still control the transmission with a carb. it will have e very single code known to man but it would move.


if it was an older TBI vehicle i could understand but the vortec EFI and OBD2 is so much better. and for the price of a new carb and distributor you can replace the spider injection system with the updated MPFI spider that has individual injectors under the intake instead of the poppets.

 

[Bill Barnes]

Well, guys, thanks for the laugh responses! However, I was hoping for some actual information, specific to the conversion...
I'm just an OR RN, not a auto technician. I could really use some first hand knowledge. FYI, the HEI distributor you replace the stock one with, ain't got no points/ condensor. I want to go old school, not ancient.

Another issue is fuel. Your fuel pump is providing around 50 psi of pressure. A carburetor can't take more than 6 psi, so you'll have to get an adjustable regulator. You'll also have to deal with the return line from the fuel rail to the tank. I see other issues you'll have to consider as they come up, too. I have a 2005 Yukon XL with 245K miles on it. I will keep my EFI, thanks. Good luck.

 

[Bill Barnes]

Another issue is fuel. Your fuel pump is providing around 50 psi of pressure. A carburetor can't take more than 6 psi, so you'll have to get an adjustable regulator. You'll also have to deal with the return line from the fuel rail to the tank. I see other issues you'll have to consider as they come up, too. I have a 2005 Yukon XL with 245K miles on it. I will keep my EFI, thanks. Good luck.

I have a Zurich XR13 OBD2 Code reader that also reads SRS & ABS codes. I got it from Harbor Freight. It's easy to use, and once you have a code, you can Google it to find the likely solution(s). It has saved me a lot of time and money. It paid for itself the first time I used it.

 

[Sptwall]

I checked on the cost of a new "spider injector" module and was surprised at how reasonable a replacement is. Keeping the EFI (thanks to you'lls feedback), but still not thrilled with that 2 piece pot metal and plastic intake manifold. I will go to Harbor Freight and get my own code reader as Bill suggested (though I never can figure out if I need the higher price models or not).

Well, got my weekend planned replacing the Multi-function Switch at the steering column and heat/ cool door actuator. I will stay away from the fuel system for now. My wife can't figure out why I like being under the hood turning wrenches for hours. I wish I knew; these trucks are a damn addiction!

 

[Mater]

if you can find one the marine version of the vortec used an aluminum intake with external injectors and rails

holley and edelbrock also makes vortec EFI intakes. you will have to get rails and external injectors for them though

here is a picture of a marine vortec intake next to a truck intake