TBI to carburetor...how hard is it?


dazada
12-03-2006, 05:39 PM
I want to put a Weiland intake manifold and Holley Street Avenger on my 1500, but how difficult would that be? I have no clue about the workings of throttle body injection, and what problems would I encounter if I were to just install a new manifold and carb?

dazada
12-03-2006, 06:07 PM
I don't know if it's a Street Avenger, but this is what Summit Racing has.

http://store.summitracing.com/partdetail.asp?part=SUM%2DCWND001AS&N=700+4294908216+4294908028+4294924760+4294840140+ 4294889107+4294925239+4294845683+1051506942+115&autoview=sku

It seems like a pretty good deal, but then again it could be too good to be true.

rhandwor
12-03-2006, 08:04 PM
If you do a search on superchargers they cover this. Basically you have to buy a kit to handle the electronics. The valves on these engines collapse at 5850rpm so you will need a new camshaft and valve springs. Probable cost close to $4000.00 but it can be done. I don't know how far you want to go.
Just the electronics will probably be at least $1000.00. I was hunting for an aluminum intake manifold appx.$500.00 plus I not sure what extras I will need.

gouldie1903
12-03-2006, 08:12 PM
you'll need a fuel presure regulator, carbs function at a much lower pressure. and you will need to change the fuel lines at the engine.

the rest i'm not so sure about but you may need to reprogram the computer. you may run into some problems with the vacuum lines tps and other sensors.

good luck and let us know how it turns out

maxwedge
12-03-2006, 08:21 PM
No electronics with a carb, the entire fuel management system is gone once the carb is installed, or did I miss something here!? Dazad what you looked at at Summit is a carb and manifold, again no computer hook up or controls to the pcm, not emissions legal either.

rhandwor
12-03-2006, 10:08 PM
I was of understanding he was putting this on a 1999 5.3L silverado. He could get a older 350 and use the dist. with electronics enclosed and get it running. I was talking about using the computer and other engine controls to fire the plugs and ect. It depends on what he wants to do.
Cost wise he would be better off rebuilding a 350 with a new dist or rebuilding a junk yard unit. He would probably need to change the trans also.

maxwedge
12-04-2006, 03:48 PM
rhandwor. Good point, but when he said tbi, that eliminated any chance of it being a late model truck, so again the lack of info throws us all "under the bus".

rhandwor
12-04-2006, 04:25 PM
I think I clicked on silverado 1999 and newer but it might have been listed wrong.

dazada
12-04-2006, 10:39 PM
It's a 1994 Silverado.

Someone said ealier that it would cost around $4,000. That's what I was afraid of. This is my "fun" truck, so if it's gonna cost $4k to convert my exsisting 350 with 200k miles to a carbureted setup, I might as well just buy a 350 crate and a 400 trans for closer to $3k.

Jegs has an upgraded TBI/manifold package for $900, but I'd rather pass on that and save for the new motor/trans.

http://www.jegs.com/webapp/wcs/stores/servlet/category_10001_12051_108231_-1_11261

(Thanks everybody for your responses too!)

Elbert
12-09-2006, 09:28 PM
It's a 1994 Silverado.

Someone said ealier that it would cost around $4,000. That's what I was afraid of. This is my "fun" truck, so if it's gonna cost $4k to convert my exsisting 350 with 200k miles to a carbureted setup, I might as well just buy a 350 crate and a 400 trans for closer to $3k.

Jegs has an upgraded TBI/manifold package for $900, but I'd rather pass on that and save for the new motor/trans.

http://www.jegs.com/webapp/wcs/stores/servlet/category_10001_12051_108231_-1_11261

(Thanks everybody for your responses too!)

What year type truck are you talking about?

its not going to cost $4k to convert to a carb if thats what you are trying to do. Personally if you just talking about swapping the intake over to a carb style and installing a carb... I think you would be better served to stay with the OEM TBI setup.

rhandwor
12-10-2006, 06:07 AM
The $4000.00 I was talking about was using the carb on a supercharger with electronics to use the existing computer. Prices have went up since close a $1000.00.
I think his idea of using a 350 engine with a dist. with complete electronics to run the engine is the way to go.

zario
01-16-2007, 03:24 AM
I would not recommended converting to carb I was thinking of doing the same but the problem is that if you have the original engine and cam it won't unless you put an external fuel pump for carburetor or you will need to replace the cam since it does not have the lobe for the fuel pump push rod

in my opinion the best you could do is go with MULTI-PORT injection I have done it and it runs great I went from TBI to TPI

Elbert
01-18-2007, 09:46 PM
if you wanted to do this why couldn't you run a regulator between the carb and the OEM electric fuel pump?

In general my advice would be to stay with the TBI setup.

jackpot5283
08-13-2007, 09:51 PM
tbi is a great setup as long as youre not goin extreme otherwise im pretty sure you can bolt a quadrajet directly in place of the tbi and an adjustable inline fuel regulator isnt gonna require a second mortgage.... simple job still not worth it ill take my tbi anyday

silicon212
08-13-2007, 11:07 PM
tbi is a great setup as long as youre not goin extreme otherwise im pretty sure you can bolt a quadrajet directly in place of the tbi and an adjustable inline fuel regulator isnt gonna require a second mortgage.... simple job still not worth it ill take my tbi anyday

TBI = two barrels and 3 bolts. A Q-jet won't bolt up in any sort of way, short of hiring Red Green or Tim - the toolman - Taylor to do it. Then, it has to work. You need an intake along with the carb, and you need an intake with 72-degree center bolts.

Which begs the question, why? Why do you want to do this? The computer is much more efficient at spark curves and fuel delivery than what the best mechanical setup has to offer.

You lose the aggressiveness of the ESC timing advance (running the timing to the edge of detonation, such as the ESC system does, not only cleans the tailpipe contents but also makes for a snappier-feeling engine), the precision of fuel delivery that EFI offers (welcome back to cold-morning engine starts and stalling until everything warms up), and the performance that actually comes with these.

scoobytuff
08-14-2007, 12:26 PM
OK, you can buy an intake for the TBI heads that will work with a carb. You will need the distributor from an older engine(one with a vacuum advance). You will need a fuel pressure regulator to get the fuel at around 5-9 psi. You can use the in tank fuel pump, but you will have to tap the gray wire on the fuel pump relay to run on keyswitched power. If you do not tap into the relay the pump will only prime. You will not need the O2 sensors if you do this so you can plug off those holes ( don't worry about this if using headers). It's really not that bad to do, and really won't cost you that much. If you want to make some of your money back ebay your unused parts. I would keep them in case for some reason you have to switch back to TBI. You will probably be ok in a non emissions state or county like where I live for a while. Emissions test are coming though, I'm not sure when. If this is not your daily driver you won't have much to worry about. Also, make sure to keep your catalytic converters, your truck may not pass visual inspection otherwise. I hope this helps. I could have left some stuff out, if so ask me.

scoobytuff
08-14-2007, 12:31 PM
Oh yeah I almost forgot. You will need to look in Summit or Jegs and get a torque converter lock up switch. Without the fuel injection your torque converter will not lock up like it is supposed to. How much this is going to cost you is solely dependent on how resourceful you are. If you can bargain and swap with buddies you may get ouot really cheap. It's quite possible the only thing you would have to buy new would be a lock up switch.

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