nimrod_sixty9

Like the title says, what are the pros and cons of going carb. How is adaptability? And yes Id like for people to post the obvious aswell.

MPG loss?
HP Gain?
Susceptibility to harsher climate conditions?
Factory gauges?
Etc...

91' L03 5-speed

camaro91

mpg loss prob depending on what you get now. prob bout 3-4 mpg
hp gain. not worth the milage loss.
doesn't adapt itself to climate. the ecm will adapt for cold starts and start everyday of the week. a carb wont do that.

and the most important. its a huge step back in technology! why are you interested in doin a carb swap anyways??

Nonni

I surely hope you are not saying that a carburated engines wont start everyday of the week.

I have both fuel injected and carb cars and they carburated cars are doing fine in cold climate. I am in Iceland and I have used carburated engines in big 4x4 vehicles driving over the glaciers and they do just fine.

My current daily driver is with fuel injections but carburated cars can be good daily drivers also.

nimrod_sixty9

Well its still just an intrest. Thats why I made this thead. There are a few things wrong with my TBI, idle, MPG to name a couple. Thanks for the info.

That must be fun. But I dont have to worry about a cold climayr anyway, here its pretty much summer year round.

Nonni

You will get worse MPG.....but not so much. A good Q-jet gives a really good MPG.

I am not sure if you will see some HP Gain if you just change from TBI to Carb (but not cam etc). I have almost no experiance with TBI (well, one of your trucks is with 350 TBI and its ok). I would prefer TPI though.

Like I said before, carburators can be really good in harsher climates. In one tour on the highlands a late sixties Ford Bronco had to tow a new Mitsubishi Pajero because some sensor was giving him a troubles. Also a friends Toyota was flooded with water when he was crossing a river and the ECM was toast. Carbs are better in taking that kind of abuse and easier to fix on the trail.

My TA was carburated so I dont know how the connections are for the gauges but I am pretty sure thats no problem.

But dont take me wrong, I really love my fuel injected daily driver but carbs are fine also.

1986Sleeper

Before you yank that TBI off and throw a carb on it try replacing the intake gaskets. 90% of TBI running and idling problems are caused from vacuum leaks. My car ran good, and idled OK. but I wasnt happy with it. I hooked it up to the scanner at work and looked at the O2 sensor while I sprayed propane around the intake, I couldnt pinpoint a certain area but it was sucking the propane up alot. I tried sprayin carb cleaner around the gaskets and didnt find a leak, but I knew it was leaking. I went ahead and replaced the intake gaskets, and TBI gasket, started it up and set the timing and I tell you, NIGHT and DAY difference. It idles perfect, has alot better throttle responce.

You really wouldnt belive the difference. Most people will do the carb cleaner trick and if they dont find anything with that method they will look elsewhere. But trust me for 20 dollars replace the gaskets.

Hope this helps.

nimrod_sixty9

Thanks for the reponses guys. As for the TBI problems, I get so many mixed messages that I dont know what my problem is. I get reponses of IAT, IAC, intake, vacuum, ECM, timing... Id rather shoot it...

Which I think Im gonna check the timing soon, hope like hell I can figure it out.

I was thinking of going to the JYard and gettin an intake and TBI unit, and port the intake and do the ultimate TBI mods, all the while I can still drive my car.

What could be my cause of MPG?

327_TPI_77_Maro

iTrader: (8)

Depends on what type of EFI you are talking about. I can't think of any pro's going from a good multiport EFI to carb. Going from TBI to carb, will give you HP gains at the expense of cold start manners and MPG.

nimrod_sixty9

It is TBI so yeah, I deff know Ill get some HP. Had an 89 Camaro with a stocker 305 with an edelbrock performer intake and holley 650 DP. And that thing would murder this 91 305 TBI, and I mean by a long shot. And seemed to get the same amount of MPG, and deff hard cold starts.

I may consider going to TPI...

five7kid

iTrader: (14)

Cons:
- Expense of conversion
- Need to modify fuel system
- Need to provide means of TV cable geometry correction
- Need to provide means of TCC lock-up
- Loss of fuel economy
- Not legal for street use in any of the 50 United States (even if you don't have emissions testing or inspection where you live)

Pros:

TexasSilhouette

iTrader: (4)

More Cons:
- constant tinkering
- smelly exhaust
- more difficult to tune

More Pros:

nimrod_sixty9

I can get all the parts dirt cheap. Cheaper than it would be for me to fix this TBI I think.
If I mod anything on this car Ill have to mod the fuel system anyway.
No need for TV cable or TCC lock-up, I have a 5-speed.
MPG is whats talking me out of it.
Car wouldnt pass an inspection if I had one anyway.

Tinkering sounds fun.
My exhaust smells horrid anyway.
This is where I was wrong, I thought it was easier to tune.

I just wish my SES light would come on so I can see the code, and find out whats up with it. Bad mileage, surge in idle when I let off the gas (mostly when AC is on), crap for power... less than it was before...

Thanks for the replies everyone. I will do as you guys recommend and keep the TBI or at least stay away from carb. Now all I need to find is a pro/con TPI thread...

SKYNOVERYA550

dumb ? but what is tv cable stand for?

TexasSilhouette

iTrader: (4)

TV=Throttle Valve, a valve in an automatic transmission that modifies shift firmness and shift points in relationship to throttle position. Also responsible for down shifts. Frequently miss-referenced as a kick-down cable.

whiley

hey five7kid
can you expand on this one a bit
being north of the border, i can run a carb'd engine no problem, drive cross country if i feel like it
in the US i don't know the rules as well,
so do you mean to say that even if i come from another state or country (Canada) in this example, say on holidays, driving my carb'd car, that i can be stopped or ticketed in some way?
is this only in some states, or all?
please explain FMI - thanks

five7kid

iTrader: (14)

U.S. registered vehicles.

whiley

okay, how about inter-state rules?
so for US registered vehicles, you can't legally run a street driven carb'd car?
or simply none will pass their next ref inspections now?
that seems unlikely to me, but i don't know the cross state emissions rules

327_TPI_77_Maro

iTrader: (8)

Read his post. It's not legal to convert an EFI car to carb'd, for emissions purposes.

kennn

Under current federal EPA requirements, you cannot remove the fuel injection on the stock 91 engine.

If you want carb in that car, you have to find a carbed 91 or newer car and swap over the entire drivetrain.