Has anyone done this?
Thread Starter
Intermediate
Joined: Jul 2018
Posts: 48
Likes: 5
From: Central Maine
Has anyone done this?
Just a thought,has anyone done away with all computer devices on a C4 1992 vintage.
I'm just thinking ,drop a carburated small block and do away with everything that's computerized ,just to keep everything simple.
Of course the nice instrumentation would no longer work and that would be a major job.,but i'm still curious if anyone has done it?
I'm just thinking ,drop a carburated small block and do away with everything that's computerized ,just to keep everything simple.
Of course the nice instrumentation would no longer work and that would be a major job.,but i'm still curious if anyone has done it?
Race Director
Joined: Oct 2008
Posts: 19,220
Likes: 1,671
From: Long Island
Did it on a 85.
Carb, 6 speed stick and no more computer issues.
Dakota Digital makes a dash conversion to regular analog gauges. There is a kit that shows up on Flee Bay every so often for the gauges.
Carb, 6 speed stick and no more computer issues.
Dakota Digital makes a dash conversion to regular analog gauges. There is a kit that shows up on Flee Bay every so often for the gauges.
Last edited by BLUE1972; May 19, 2019 at 11:04 PM.
Intermediate
Joined: Mar 2019
Posts: 44
Likes: 15
From: Seattle suburbia... for now
Why? Easier to clean/replace injectors than to rebuild a carb. Don't have to worry about the carb gunking up if it sits for a while... even a month or two with a carb can cause problems especially with E10. Fuel injection is more efficient than any carb... even on a C4. You lose all of your factory instrumentation if you throw away the ECM, and a new analog panel would cost more than getting the panels rebuilt (if they aren't working) and replacing the ECM. I owned my C4 the first time for 14 years and the only problem I had with the fuel injection system was when mice got into the injector wires when I had it parked for a couple of months... not a big deal to repair. Going to a carb costs money, staying with FI and the digital dash costs nothing. Oh, and you will kill any resale value by doing this.
What am I missing?
What am I missing?
Last edited by obijohnkenobe; May 20, 2019 at 05:38 AM.
Safety Car
Joined: Mar 2003
Posts: 3,583
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From: Indianapolis IN
Finalist 2020 C4 of the Year - Unmodified
C4 of Year Finalist (stock) 2019
I am in the "Why???" camp too. The ECM and all associated systems are actually pretty simple, and VERY reliable. It's only complicated if you don't understand them and have no 'willingness to learn them. Once you study and completely understand how everything works and interacts, you'll see how simplistic it all really is.
But then again, it's your car. If that's what you want to do, then more power to you...have at it!
But then again, it's your car. If that's what you want to do, then more power to you...have at it!
Le Mans Master
Joined: Apr 2000
Posts: 5,713
Likes: 105
From: Manassas VA
If your LT1 engine is in good shape, have you considered this? https://www.summitracing.com/parts/NAL-24502592/. Then you could add carb of choice, along with a standard SBC HEI dist......
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Safety Car
Joined: May 2001
Posts: 4,759
Likes: 1,647
From: Fairfax Virginia
Add another person to the WHY? camp.....
The value of the car will probably go down after such a swap. Fuel Injection is a step "forward" from carburetors. I have four carburetors for my C3 and use which ever seems appropriate for my planned usage. Trying to maintain a carburetor today is much more challenging with the ethanol issues. The last time I pulled into a shop with a carburetor the mechanics fled as they never touched one before they told me. Mine will not be the "first" for anybody unfamiliar with how they are supposed to work.
I agree with Red86Z51 I would get everything you can online about the system and read them all. Once you get passed the "fear" of fuel injection it is actually a pretty straightforward system to work on.
I found a book by a gentleman named Charles D. Probst at Bentley Publishers called "Corvette Fuel Injection and Electronic Engine Management" and it covers the following fuel injection systems in great detail. It covers the L83, L98, LT1, LT4, LS1, LS6 and the ZR-1. It is a book on "How to Understand, Service and Modify" Corvette fuel injection systems.
Best Regards,
Chris
The value of the car will probably go down after such a swap. Fuel Injection is a step "forward" from carburetors. I have four carburetors for my C3 and use which ever seems appropriate for my planned usage. Trying to maintain a carburetor today is much more challenging with the ethanol issues. The last time I pulled into a shop with a carburetor the mechanics fled as they never touched one before they told me. Mine will not be the "first" for anybody unfamiliar with how they are supposed to work.
I agree with Red86Z51 I would get everything you can online about the system and read them all. Once you get passed the "fear" of fuel injection it is actually a pretty straightforward system to work on.
I found a book by a gentleman named Charles D. Probst at Bentley Publishers called "Corvette Fuel Injection and Electronic Engine Management" and it covers the following fuel injection systems in great detail. It covers the L83, L98, LT1, LT4, LS1, LS6 and the ZR-1. It is a book on "How to Understand, Service and Modify" Corvette fuel injection systems.
Best Regards,
Chris
Burning Brakes
Joined: Sep 2008
Posts: 810
Likes: 58
From: Alva Florida
Not critical of your decision, but a 1992 has the optispark ignition, and is completely computer controlled. You would have to swap the engine out with a 1987-1991 (One piece rear main seal, roller block). If you are willing to do that and the computer controlled transmission too ~ it would be doable. Your car ~ your decision. You will also need the appropriate fuel pressure regulator to get fuel pressure down to carbed pressure also.
Drifting
Joined: Jun 2018
Posts: 1,678
Likes: 229
From: Michigan
This isn't the crappy CFI that was sitting on a crappy motor or a long runner TPI design. There is literally no benefit here other than you don't have to learn something new.
More Emissions
More Maintenance
Worse Gas Mileage
Less Power
Lower Value of the Car
A lot of work
Why not just sell and buy a C3 if you wan't to be old school?
More Emissions
More Maintenance
Worse Gas Mileage
Less Power
Lower Value of the Car
A lot of work
Why not just sell and buy a C3 if you wan't to be old school?
Last edited by KyleF; May 20, 2019 at 12:44 PM.
Race Director
Joined: Oct 2008
Posts: 19,220
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From: Long Island
I did the math , for half the cost of "fixing the injection I did a carb. It must be 10 years now. No issues with the carb, fuel system. Car runs as good if not better than with the computer.
Also if I break down , I can walk into Auto Zone and for $300 put a new carb on it and drive home. How much is an Map sensor....
When I was out injured for a very long time, after a bad accident - the only cars that ran with no issues were the carb cars.. The 2 computer cars threw codes..
Almost all carbs made after 2000 are ok with the AL in the fuel, check before you buy.
Build the car as you want, but most important drive it and enjoy it. I do....
My truck only went , 37 years and 480,000 miles on it's carburetor before I replaced it. Cost me $400 for the carb and manifold - I upgraded to a 4 barrel. I did the cap and rotor at the same time - $35.00.
It still runs great.
Also if I break down , I can walk into Auto Zone and for $300 put a new carb on it and drive home. How much is an Map sensor....
When I was out injured for a very long time, after a bad accident - the only cars that ran with no issues were the carb cars.. The 2 computer cars threw codes..
Almost all carbs made after 2000 are ok with the AL in the fuel, check before you buy.
Build the car as you want, but most important drive it and enjoy it. I do....
My truck only went , 37 years and 480,000 miles on it's carburetor before I replaced it. Cost me $400 for the carb and manifold - I upgraded to a 4 barrel. I did the cap and rotor at the same time - $35.00.
It still runs great.
Last edited by BLUE1972; May 20, 2019 at 01:05 PM.
Le Mans Master
Joined: Apr 2000
Posts: 5,713
Likes: 105
From: Manassas VA
I agree
With that intake I linked above, he can do the same thing with the LT1, Intake, carb, and HEI distributor will eliminate the OPTI, and all of the fuel injection. Dont know for sure, but all of your guages should continue to work as is. The Tach may require some different wiring..... He then would have the LT1 higher lift cam, higher compression, and better flowing heads.vs a SBC swap.
Last edited by 93 ragtop; May 20, 2019 at 03:05 PM.
Burning Brakes
Joined: Sep 2016
Posts: 1,133
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From: Ohio
I can walk into Auto Zone and for $300 put a new carb on it and drive home. How much is an Map sensor....
Carburetors have their upsides. Easy to maintain and fix. Thats about it. They're typically worse at everything else.
Le Mans Master
Joined: Apr 2000
Posts: 5,713
Likes: 105
From: Manassas VA
Joe, I would agree to keep the factory system is probably the best way to go, if, you are keeping the engine stock or close to stock..... (keep in mind the OP has a 92)
But, if he is modifying the motor, ie stroker, etc. Something that is going to require, injectors, bigger throttle body, etc. IMO there is little to like about the 85-95 OBD1 systems.
It is getting harder to find someone who is capable and willing to tune them. And its expensive when you do.
If it is a toy that he occasionally drives, and he wants to make a hotrod out of it, There is some advantages to a intake, carb and hei dist. For $1,000.00 or so.....
Again this is just my opinion, But on a modified motor, I can see advantages to a carb conversion, or something like a holley HP self tuning system, or even a LS swap . But I see little advantage in keeping a OBD1 system on a modified motor, these days....
Oh, one other comment that has been made, "The value of the C4 will be hurt with this mod" Again, my opinion, but most C4 vettes are hard pressed to sell for more then $5,000.00 and probably never will bring much more. As a whole, these are not collector cars, Modify it, make it into what you want and enjoy it!!
Drifting
Joined: Jun 2018
Posts: 1,678
Likes: 229
From: Michigan
Oh, one other comment that has been made, "The value of the C4 will be hurt with this mod" Again, my opinion, but most C4 vettes are hard pressed to sell for more then $5,000.00 and probably never will bring much more. As a whole, these are not collector cars, Modify it, make it into what you want and enjoy it!!
Your opinion doesn't reflect the general market when you go to sell a car. Ripping the injection system off and replacing it with anything is going to scare a lot of buyers away.
It pigeon holes the car to only attract a certain type of buyer.
As far as carb running for year and miles... the ability to run and drive is a low bench mark. You are not quantifying how it did on gas mileage, emissions, or if it really made full power as there was nothing there to monitor the performance.
Intermediate
Joined: Mar 2019
Posts: 44
Likes: 15
From: Seattle suburbia... for now
C4 values/prices are all over the place. A C4 in excellent condition will bring above $10K... well above. I guess there are two types of owners here, folks who want to maintain their C4 and upgrade it in a way that keeps or increases value, and folks who want to hotrod a C4 for the lowest cost and care less about originality. I'm in the former camp, because I see these cars as a piece of history that we can hand to others instead of a simple thing that we can thrash and trash and then discard. Not saying I'm right, or better... but the more thrashers and trashers, the more valuable will be the C4s that are maintained. I'm seeing 2nd gen F bodiy Firebirds (especially Formulas and Trans Ams) go for north of $30K in very good or better condition... even restored ones. I think that within a decade my C4 will double in value, and will probably rise to the mid-$50K range in the next two to three decades. I'll likely put 50K miles on it in the next 20 years (put 44K on it the first 14 years), and likely rebuild/restore it to as-new condition if needed.
Again, if I were buying an under-$5K C4 that was thrashed, then I might consider going carbed if the engine and electronics were trashed... or actually I'd avoid that car and buy something decent that worked. YMMV.
Again, if I were buying an under-$5K C4 that was thrashed, then I might consider going carbed if the engine and electronics were trashed... or actually I'd avoid that car and buy something decent that worked. YMMV.
Thread Starter
Intermediate
Joined: Jul 2018
Posts: 48
Likes: 5
From: Central Maine
Well,that 's a lot more responses than i expected.
It was just a question to see if any people have done such a conversion and how they went about it.
My '92 is all original,has about 135k miles on it and it's very well maintained.
Right now it backfires and stumbles from idle but then it accelerates fine.Last summer the code for the EGR came on twice so i hope that's what causing the problem i'm having.
Ordered a new valve and solenoid today,will see if that is all for now.
If i had a bad motor and tranny doing such a swap might make sense but it's not something i'm contemplating,financialy it would cost a ton of money.
I do like the simplicity of the earlier times but we can still work on the C4s without having to take em to a dealer and i do like the idea of getting 25mpg when i drive 200 miles down the coast.
It was just a question to see if any people have done such a conversion and how they went about it.
My '92 is all original,has about 135k miles on it and it's very well maintained.
Right now it backfires and stumbles from idle but then it accelerates fine.Last summer the code for the EGR came on twice so i hope that's what causing the problem i'm having.
Ordered a new valve and solenoid today,will see if that is all for now.
If i had a bad motor and tranny doing such a swap might make sense but it's not something i'm contemplating,financialy it would cost a ton of money.
I do like the simplicity of the earlier times but we can still work on the C4s without having to take em to a dealer and i do like the idea of getting 25mpg when i drive 200 miles down the coast.
Race Director
Joined: Oct 2008
Posts: 19,220
Likes: 1,671
From: Long Island
The car runs great , little maintenance. As far as power - it's great. No bog and no flat spots. Starts on the first hit of the key.
I'm getting better gas mileage (26) than the factory setup, but then again I now have a 6 speed.
I get 25mpg with my 71 and 5 speed.
I needed a map sensor, Mass air flow , cold start injector, IAC, injectors and other crap. It would have cost over $1200. in parts for me to do it. Yes I can do fuel injection, but also remember this is a OB1 computer...
The carb was $275 ( factory re-manufactured) , manifold $125 and the new HELI Distributor was $99. The fuel pressure regulator was $65. All on sale at a local speed shop. That was it, good to go.. Took less than a day.
It's now as reliable as my 67, 71 and 72. almost forgot my 1980 truck... turn the key and go
I'm getting better gas mileage (26) than the factory setup, but then again I now have a 6 speed.
I get 25mpg with my 71 and 5 speed.
I needed a map sensor, Mass air flow , cold start injector, IAC, injectors and other crap. It would have cost over $1200. in parts for me to do it. Yes I can do fuel injection, but also remember this is a OB1 computer...
The carb was $275 ( factory re-manufactured) , manifold $125 and the new HELI Distributor was $99. The fuel pressure regulator was $65. All on sale at a local speed shop. That was it, good to go.. Took less than a day.
It's now as reliable as my 67, 71 and 72. almost forgot my 1980 truck... turn the key and go
Last edited by BLUE1972; May 20, 2019 at 09:49 PM.
Race Director
Joined: Oct 2008
Posts: 19,220
Likes: 1,671
From: Long Island
I should have said IAC or MAFS. , after you figure out what it was... my bad..
Most people think a 1000 CFM carburetor will make them faster, if they chose the proper size and type for the street - their cars would run better - like a 600 CFM on a SBC 350.