Converting old school carb'd cars to FI?

I didn't want to hijack the thread Robbie started, so I'll create one here.  I recently picked up a '77 Corvette.  Such a cool story...I got it from the family of the original owner.  It was her mothers' daily driver when new.  Mom got into track days, and so did daughter.  They ran it together.  When mom decided to hang up her racing shoes, daughter and her husband took the car.  It's lived as a track day special since.  Race suspension, aluminum radiator, heated up 350, 4spd (original).  It's was running HPDE with Chin at Sebring....some people here may have seen it.  Anyway, daughter sold it to me so that she can finance her own daughter running karts.  

The car is so cool.  It's a worked over 350 with a carb on it (don't recall the carb specs).  It needs a good tuning, as it had just been rebuilt and quickly put back on before they sold it to me.  Before I go down that path of having the carb tuned (I have no idea how to do it), considering converting it to fuel injection.  Obviously, lots of "pros" and few "cons".  I just don't know much about that.  Without buying some made in Taiwan special, what would be the most cost effictive and efficient way to convert the car?

Holly terminator or sniper 4bbl tbi kit, surge tank for fuel starvation purposes. 

Ill be doing an install in a 68 cuda in a few weeks if you want to wait and see how one goes together. 

Holley Sniper kit for cars with hopeless OEM carb setups (Ford six cylinders come to mind). But...

The cost/benefit for a street driven car doesn't make sense, IMO.  Carbs are just toilets for fuel. They really aren't these mystical beasts most people think they are. Tuning is really pretty easy.  This is just one of several videos Luke Finley has about carb and ignition tuning: Holley & Edelbrock carb tuning. The main tuning tool is your vacuum gauge. Tony DeFeo shows you what to do here:  Fine tuning with a vacuum gauge. 

I'd rather turn screws to tune than wire in sensors.

Sorry, I should have been more clear.  Yes, I will drive this car on the street for fun.  However, its' primary purpose in life is for HPDE.

I have a Holley Sniper Stealth setup on the Camaro that is controlling spark as well.

Frankly, I kinda wish I had gone for a MPFI option.  The Sniper is fine, and for a street car it is probably great, but I've run into some issues in a race application.

Tuning on a big cam almost requires a dyno.  If you have good engine vacuum, it's probably not an issue.

Fuel starve is real - I'm now running a Holley Hydramat.

The Sniper "Stealth" - aka, the one that looks like a carb -  is different internally and fires the wrong injectors if you want to use a "progressive" linkage.

Overall, the ECU is limited.  If you want to do cool stuff with EFI other than enjoy a cruiser, you might need to upgrade.

In reply to Gimp (Forum Supporter) :

That's kind of what I'm debating...how far down the rabbit hole do I want to go.  I don't need or want to set the fast time of the day.  I just want steady and reliable.  I'd love to do away with the quirks of a carb, along with the smell...car is parked in the garage next to my wife's car and she doesn't want that smell in her car.  I also don't want to spend crazy money, so just trying to see what the cost would be to go FI.

If carbs are toilets. TBI is like E36 M3ting in it first.

As someone who converts/tunes a lot of these it goes like this Sequential port EFI > Batch Port EFI >> well tuned carb >> nearly any TBI setup

Even a "great" TBI with a capable ecu and tuner is still a POS compared to the other options. It's workable if all you want to do is putter around at lower loads. For any sort of performance, forget it.

Go all the way to port efi, or not at all. IMO

(one caveat, we did build a twin turbo, quad TBI (4x 2BBL), mud truck that ran on methanol that worked pretty well but we had a wide acceptance range and measured fuel consumption in gallons per minute)

Might be a dumb question, but I do remember back in the day that the late C3's were some of the earliest PFI motors on the market- so can't you get a PFI intake for that motor pretty easily?  

In terms of tuning, it would be the same process do to that as it would be for TBI, but it would be a lot better.

Have to set up a fuel pump/fuel system for both.  Have to set up wiring for both, have sensor sets for both.  Etc.  The biggest difference between TBI and PFI would be 4 injectors in a body vs. 8 injectors in a manifold.  And that's why I was wondering about the availability of an already finished PFI intake system for that engine.

In reply to Paul_VR6 (Forum Supporter) :

Heard.  I may wind up just sticking with the carb and finding someone really good at tuning it.  

alfadriver, yes the '82 had what they called "Crossfire" fuel injection.  From my knowledge of it, it's a E36 M3 system.  The engine in my car isn't original, that one went kaboom a long time ago.  It's still a 350 though.

I would try and do some digging. I don't think the crossfire "hardware" is bad, but the bits it was attached to. With a modern efi computer likely sins can be forgiven.

Well, if TBI is bad then crossfire is double so.  I have an 84 Corvette with that system.  It is two small single barrel TBIs, each feeding 4 cylinders with a convoluted and poorly flowing intake manifold.  Totally out of breath at 4K, and doesn't seem to work all that well.  I understand why people convert these to carbs.  

Paul_VR6 (Forum Supporter) said:

I would try and do some digging. I don't think the crossfire "hardware" is bad, but the bits it was attached to. With a modern efi computer likely sins can be forgiven.

+1.  I would use the crossfire as just a manifold and a place to have fuel injectors.  Don't even carry over the wiring harness.

Sonic said:

Well, if TBI is bad then crossfire is double so.  I have an 84 Corvette with that system.  It is two small single barrel TBIs, each feeding 4 cylinders with a convoluted and poorly flowing intake manifold.  Totally out of breath at 4K, and doesn't seem to work all that well.  I understand why people convert these to carbs.  

Is there a C4 intake system that would work?  Those were reasonably healthy engines.

And there could be enough aluminum in the castings to port them out.

I'm a member of the keep it simple club when it comes to old cars used for HPDE. The simpler everything on the car is, the more likely you won't have problems at the track. Working on the car at the track during your session sucks, luckily I've only had to do it once because of a tire failure.

You're not really trying to "win" anything so gaining the last amount of power possible isn't important. If your gas mileage isn't quite as good as FI who cares?  Adding any type of FI increases the number of electrical things that could go wrong, increases the number of fuel system things that could go wrong, etc.  You could spend a weekend at the track instead of spending the money on FI and a weekend  (or longer) installing.

Replace old flexible fuel lines with more modern ones and your odor might be reduced.

A few of things here:

I have 4 carburetted vehicles in the garage and there is not even a hint of gas smell in the garage................ever. If you do have a gas smell something is leaking.

Carbs are stupid simple to tune; for those not familiar with them an hour worth of reading will teach you what you need to know.

Carbs are also reliable; in the last 30 years I've had one carb issue (bad float needle). Note I've had one injector fail in that time.

Once properly set there should be no issues. When the Datsun had an aggressive cam in it I spent 30-45 minutes on a dyno fine tuning it. I'm lazy when it comes to tuning, I set the car up for the cooler months and then leave it. Yes the car runs a bit rich in hotter months but I'll trade the 3-5hp lost for not having to touch it.

Stick with the carb; simply make sure it's in proper working order.  You are fixing a problem that doesn't exist.

alfadriver said:

Sonic said:

Well, if TBI is bad then crossfire is double so.  I have an 84 Corvette with that system.  It is two small single barrel TBIs, each feeding 4 cylinders with a convoluted and poorly flowing intake manifold.  Totally out of breath at 4K, and doesn't seem to work all that well.  I understand why people convert these to carbs.  

Is there a C4 intake system that would work?  Those were reasonably healthy engines.

And there could be enough aluminum in the castings to port them out.

I feel like there is an off the shelf TPI solution but I honestly don't know what it's from or what it's really called.

alfadriver said:

Might be a dumb question, but I do remember back in the day that the late C3's were some of the earliest PFI motors on the market- so can't you get a PFI intake for that motor pretty easily? 

They were not port injected.  The Cross-Fire EFI system was two TBI units mounted on a crossram manifold with fairly long internal runners.

Chevy then made the long runners out of tube, bent them upwards to meet a central plenum, and added port injection, calling it the TPI system, but that is well post-C3.

Having worked with a couple of those bolt-n-pray EFI conversion systems, a decent Quadrajet is better in every way.

Pete. (l33t FS) said:

Chevy then made the long runners out of tube, bent them upwards to meet a central plenum, and added port injection, calling it the TPI system, but that is well post-C3.

This is the one I am thinking of. Won't these (or the replacement versions) bolt to an old school sbc?

TPI is one of the coolest intakes GM ever made.

I'd go with a First TPI intake and whatever ECU you want (megasquirt, LS, Holley, etc) since the stock TPI falls on it's face at 4500 on just a stock engine.

alfadriver said:

Paul_VR6 (Forum Supporter) said:

I would try and do some digging. I don't think the crossfire "hardware" is bad, but the bits it was attached to. With a modern efi computer likely sins can be forgiven.

+1.  I would use the crossfire as just a manifold and a place to have fuel injectors.  Don't even carry over the wiring harness.

The crossfire intake is actually based on the old 302 z28 cross ram intake 

Tom1200 said:

Carbs are stupid simple to tune; for those not familiar with them an hour worth of reading will teach you what you need to know.

what books or YouTube videos would you recommend .

 I would like to understand them better , 

Thanks

californiamilleghia said:

Tom1200 said:

Carbs are stupid simple to tune; for those not familiar with them an hour worth of reading will teach you what you need to know.

what books or YouTube videos would you recommend .

 I would like to understand them better , 

Thanks

They tend to be carb type brand specific but the concepts are the same; they typically all have an idle, low speed and high speed ciruit.

If the car is equiped with an air fuel ratio gauge makes it easier but you can do it without one. The long time method was doing spark plug readings but it's rather time consuming. 

For instance this is the one I used for tuning the Keihin flat slides on the Datsun. 

http://www.factorypro.com/tech/tech_tuning_procedures/tuning_FCR_Burns,Pat.html

Previously the car had Hitachi SUs

https://web.archive.org/web/20100815030120/http://www.jetlink.net/~okayfine/sutech.html

I also found this on Holly carbs

https://www.holley.com/blog/carburetor_installation_and_tuning/1/

Interesting discussion. I'm looking at plowing some funds into my '69 Olds (455/TH400) and an EFI setup was on my radar. The Quadrajet on it does an okay job I guess, so maybe I'll just get the carb rebuilt and spend the money on a different intake instead.

I put an efi system on our street only bronco expecting it to be awesome.  Started with fitech and it had problems.  Got a holley sniper and it was defective so they replaced it. 
 

now it's in and running good.  But frankly, it wasn't worth it over the carb that I broke the engine in with.  I had expected to be able to reach in, turn key and start it easily.  But I need to wait for it to prime shot and then it still needs a little dance on the gas pedal.  
 

but I've already dumped loads of $$ and time into the fuel system to make it work so I'm stubbornly sticking with it. 
 

I agree with Paul's assesment.  Go with a good factory efi system and the gas tank and lines to go with it or just stick with a carb.  

Screw factory EFI you have to be a wizard with expensive software to tune them.

MEGASQUIRT

I have more than one system that has passed DEQ one that runs 20# of boost.

There is a reason none of the OEMs use TBI any longer......