I am planning to convert from TBI to carb. I want to do it in stages due to the expense involved.

Can I install a vacum advanced HEI Dist. and still utilize the ECM controlled TBI fuel delivery system until I can afford the rest of the components I need for the conversion?

Any help will be greatly appreciated.

 

I think you can keep your computer controlled HEI. Don't quote me. Why do you want a carb?

 

I want to go to carb for a few reasons.

First, since I installed the headers I noticed that the engine really sucks air hard under acceleration. I think the the two barrell TBI is restricting my high end horsepower.

I also have big plans for my Camaro. I want to build a high outut 350 or 383 vortec motor and I think a carb would be much easier for me to tune well. I I really don't think the TBI will support 400 plus horse power.

I see the carb conversion as the first step toward that goal. I don't have the money for a full on crate motor so I will have to do this build up in stages.

Also, I hate to pay for upgrade componets that dont fit into my long term plans. For example I regret buying the chip I have now that I realize that it is just not going to cut. it.


-Lance

 

I'm gonna go ahead and tell you what people will say (or would have said had I not posted this). You'll hear "TBI CAN support 400+ HP", "EFI is better than carb, carb sucks" "TBI can make just as much HP as carb"...etc. Well here's what i've learned through my experiences. Sure, if you put a TBI setup on a car, it can SUPPORT good HP....but it wont help MAKE the HP. You'll have to give the TBI the works just for it to be sufficient enough for the motor...then what? There are guys running pretty quick on these setups, but in order to do it, they had to throw hundreds of dollars into their TBI setup (670TB, 350 injectors, AFPR, eprom, intake manifold, etc.) those things alone add up to over $500 (assuming u want all new parts). But you can get a good new carb for $230 or so...and have the HP capacity and simplicity that TBI can't offer. Yes TBI is simple, but carb is rediculously simple. I'm not downing TBI, i'm simply saying that if you have "big plans" for this motor, TBI is not the way to go, because if will eventually become your bottle neck, and have to be replaced anyways. Carb is cheaper, simpler, and makes more power.

 

Yeah I agree.

I am not slamming TBI because right now my car will smoke most cars I encounter on the street.

What I really whant to know is will my ECM controlled TBI fuel delivery system continue to operate if I phase in a vaccum advance distributor. I want to move toward a mechanically tuned system as opposed to an electronically tuned system (I think it will be more simple/versitile). But I can't afford to do it all at once. Plus I want to work through all of the "gremlins" one at a time.

Do you guys know what I mean?


Man I just want to whoop a$$ on the street!

-Lance

 

What a bout a single plane mulit port ignition? LT1 intake, Holley intake, TPI, you have lots of choices. Pinpoint accurate tuning. I can only see the benefit of going to carb if you know how to tune one. Other wise you might as well learn to tune TBI. You already have it.

 

Hey Tas. What's up? I've seen tons of your postings. I respect your views.

It seems like my TB has very limited air flow. Do you know how many cfm the stock LO3 TB is supposed to flow?

That is a greater concern to me than it's ability to deliver fuel.



-Lance

 

Hmmm. I'm not gonna give you a yes of no answer...cause i'm not sure. But I dont think you can do it. I believe this because the ECM works by taking the input of sensors and such to adjust...and if there is no computer controlled distibutor there...i dunno if the car would even start, and if it did start, i dunno if it would be able to get a timing reading, which is very important. But like I said, this is me making an educated guess w/out looking into it of giving it deep thought. I've never heard of it being done, but maybe is has been and is possible. I think it would be simpler to just wait and do it all at once. I was going to do the swap about a year ago, bought all the parts to do it, and it didn't cost me too much.

 

stock should be 480 or 520 if I remember. Holley 670 TBI is 670cfm.

 

Somewhere in the neighborhood of 530cfm.

 

Please don't mis-understand me. I have heard of some great success stories with 670 holley TBI and 454 GM TBI and so forth.

It is not that I think TBI is necessarliy insufficient. I think it would be simpler(less time consuming) to swap a couple of jets in stead of re-program a fuel curve.

Tas, do you know if i can run a vaccum advance dist. off of one of my TBI vaccum ports and cut the ECM out of that part of the equation while still relying on the ECM and TBI to deliver air and fuel?

Hot Rodders need to know.


-Lance

 

Ok so maybee my stock TB could deliver as much as 530 cfm. An aftermarket piece can deliver 670 cfm. That's cool. But once I free myself from the ECM I could drop a 750 or 1000 cfm carb on my motor. Or maybee two 1000 CFM carbs! Whatever I need.

That's not my plan but that is the type of versitility that attracts me to mechanical tunning.

I don't mean to offend anyone. I should count my blessing because here in Wisconsin I don't have to submit to emmissions testing.

Tas, is that why you are so loyal to our TBI platform?


Lance

 

I dig TBI, TPI, EFI, MPFI or whatever electronic fuel injection because its plug in and go. I had a carbed GM and I hated it. I have a carb jeep and I also hate that stock carb. My dad has 3 carbed vehicles they are a pain in the butt if you don't know how to tune them. Even if you do, its still a pain. With EFI, you plug in a computer or hand held device and see what is the matter. There is no cold moring stalling, there is no steep angle sputtering or stalling, no flooding, no mid intersection prayer sessions to hope the carb won't cut out before that oncoming car gets to you, and so on......

You can run carb with the electronic distributor or the TBI without an electronic ignition but you need to get into the chip.

 

Tas, that's cool man. I appreciate your input. It has been a long while since I owned/drove a carbed car. And your right at times it really sucks. They flood out, etc.

My TBI has run very strong day in day out and never a problem. I mean smooth!

But I subscribe to four hot rod magazines a month and none of them is telling me how to reprogram my PROM. It's all about jetting; carb tuning. You know what I mean? I dont know $hit about where to get chip burning hardware or how to match a fuel/spark curve to my application.

Is it really no big deal to run a new vaccum advance HEI Dist. and still keep my TBI ECM happy?

I just want to haul a$$!

-Lance

 

You are right, there is a lot less info on hot rodding a TBI than there is for a carb equipped car or even TPI. That's why we are here. Yes you can go "old school" and swap it out for a carb. But IMO you will have lots of driveability issues to deal with as well. I don't miss the cold start, vapor lock, choke setting and fouled plugs that I dealt with LONG ago. Now I let the computer deal with all that. Simplicity comes with rewards and pain. A word of advice though, don't cut and trash the wiring for the TBI in case you change your mind later. Good luck, Lon.