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Discussion Starter #1
I own a 1990 GMC Sierra. I want to ditch the tbi and run a carb. Does anyone know of a site that i can go to, to find out what all i need to do to switch it over and it run right?
 

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Uhrm, good luck. You'll need a different intake manifold most likely, different ignition system, different distributor, different guages....I don't know of anybody who has done it.



What I want to know is, why? :think:
 

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your best bet would be to just throw in a carb crate motor. less to mess with

why is a good question.....neither one is going to be a huge power maker(unless you put a HO crate in)
 

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hey jeff, im looking to convert mine over to a carberated with a new motor. Only problem is i dont have the money right now for the new engine. Plus even if i did i would still be trying to figure out what all has to be done for the switch.
 

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Whifflebat said:
Uhrm, good luck. You'll need a different intake manifold most likely, different ignition system, different distributor, different guages....I don't know of anybody who has done it.






What I want to know is, why? :think:

carb will make more power, however good luck with emissions...

I found this interesting, but edelbrock even now has a conversion kit for the LS1 to carb'd, so you might want to check and see if there are any kits out there.

If there is not, then don't do it unless you a pretty damn experienced. Tuning carbs is pretty hard...
 

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Making more power with just a carb is not entirely true on this motor. The reasons this motor doesn't make much power is the cam, heads, intake manifold, along with the TBI. I feel that if you keep the same engine/heads/cam and go with a carb, you're going to be disappointed.
 

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I think u will regret going with a carb. I dont know how cold it gets were u live, but sittin 5 mins in a cold ass truck waitin for it to warm up is a pain. Like GMCTrk said, tuning carbs is pretty hard. Im no expert, al know is my 86 had a carb and i had to wait forever for it to warm up or it would run shitty and die, and i was always trying to tune the choke and jets and stuff. All my buddies were the same way. I couldnt be happier now that my truck is FI.
 

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I'm trying to figure out the correlation between having a carb and slow warm up times... as far as I know there should be no difference, both FI and a carb feed fuel into the engine... Only thing that I know of that would cause a slow warm up is a stuck open thermostat...
 

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Discussion Starter #11
Im not sure what kind of fuel setup i will run. I just know for sure that i want to ditch the tbi that came on the truck. If anyone has any suggestions of a fuel setup(anything other then tbi) post them please.
 

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Carb isn't that bad, look how long it has been around. And switching from TBI to carb right with your current setup (assuming of course you change intake manifolds) will yield you a pretty good gain. All things being equal a carb will warm up just as fast, but most FI setups do seem to warm up faster then most carb setups. A functional and properly tuned choke will help with this tremendously.

TBI isn't all that great when it comes to power. TPI is an expensive setup that doesn't do much up top.

Aftermarket setups are expensive, and often times adapting newer technology GM FI setups is an expensive thing.

It is NOT that hard to tune a carb. It will take time to pick up the art yourself, but finding somebody shouldn't be hard at all. There is a local guy around here that will tune your carb and dissy timing for $10. And props to ANYBODY that can tune that setup after he gets done with it and make more power.

It is possible to change to a carb setup and retain the ECM controlled timing. Whether you want to have the computer control your timing or not is completely up to you.

To change to a carb will require a new intake manifold (a pre -87 intake WILL work), a carb, and a AFPR or new fuel pump. Your TBI's fuel system runs on about 14psi IIRC. A carb wants 5-7.

Of course if you want to change the dissy out you can. Pick up a HEI one and throw her in there....
 

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brodystruck said:
And switching from TBI to carb right with your current setup (assuming of course you change intake manifolds) will yield you a pretty good gain.

The improvement he will notice will come from the better flowing intake manifold, and NOT from switching to a carb. :read:
 

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I have to disagree on the carb warming up as quick as FI. I have know a lot of people with carbed vehicles, and they just wont run right when first started. They will die or run shitty. I can get in my FI 97 and floor it right after i take off and it will run great, no stalling. Cant anybody back me up on this?
 

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Engine temp. A cold carburated motor runs like crap.
 

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Thats odd. Since the carb just feeds fuel to the engine, like a FI system, it should warm up about the same rate...

The other mechanic at philmont put together a carbed motor in his 83, and his started almost as easily as mine and ran nice and smooth, even after sitting a few days...
 

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Maybe its cause all carburated vehicles are old and thats why i think they run like crap when it is first started. Maybe a new or rebuilt motor with a carb would be ok. My truck and all my buddies trucks run great after about 4 or 5 mins. And i even had mine tuned by 2 diff mechanics. Does anyone drive an older truck?
 

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i drive a 74 blazer with a 4 bbl quadrajet. I can actually notice a difference performance wise when i first start in cold weather as opposed to hot weather. I don't have to wait very long becuase i live in southern california where the low temp is actually not that cold. I think that in colder climates waiting a longer time would be a must
 
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