L98 TPI to Carb
 

Who has switched over from TPI to a Carb and did it make a difference?
Were you able to pick up RPM's with the switch, I know I will lose mpg's but I put less than 500 miles on my vette last year. I also am not picking up on the fuel injection.:willy: Just looking for some input :cheers:

Difference in what ?
Read
http://forums.corvetteforum.com/sear...rchid=10180086

I guess I would question what issues you have with the fuel injection? And what you mean by more r.p.m. There will be issues with hood clearance to the carb given that the car was not designed to have a carb sitting on the top of the engine. Not saying it can be done, just curious why?

Lets face it the C4 is not cutting edge technology, its main appeal is its roadster like ride qualities. I grew up driving carbed cars, and that is what I like, same thing with a manual transmission. If you want to be chauffeured around by a robot, go ahead, but don't cry when the machines take over and you can't do anything for yourself.

It was when it first came out 25 years ago , just like the C6 is now.
Still using your 8 track?

If you carb it, you should get higher rpms just like the 350s of old. The TPI is whats holding the L98 from achieving that (along with a restrictive exhaust). Im not sure what the horsepower increase will be with a carb on the L98, but there is a engine Im thinking about getting called the ZZ4 that is rated at 355hp with a carb,but with the tpi that I have now will only be about 265hp, so you can see there is a great difference in hp between TPI and carb. Higher power can be achievied with TPI but the cost is much greater.I personally won"t go to carb, because thats not how the car was built originally,but if power is what you want, it can be gotten cheaper and easier with a carb..WW

Switching to a carb is not cheap,Intake,carb,air cleaner,FPR,Dizzy,TV cable bracket :cheers:

:iagree:Nothing is cheap nowadays but a lot of this can be bought used on ebay an other sites fairly inexpensively. Just go to ebay an do a seach on 350 intakes or carbs and see if you don't come up with hundreds of items...WW

Not sure how you equate a carb with higher engine speed? The L98 was designed to make h.p./torge in an era when fuel and emission were the still the controlling factor in engine development. As some one already eluded, even the LS9 which makes in excess of 600 h.p. does not run at what would be considered high engine speeds.
I agree that a better intake manifold would increase both the engine operating speed as well as some of the usable horsepower, but for the sacrifice of the lower end torque.
Trying a larger throttlebody and a les restrictive manifold might surprise you. There are numerous articles that you can find on the Web that show improvements in h.p. by increaseing the intake flow and decreasing the exhaust back pressure.

Nothing comes up. :crazy:

Maybe a dumb question, but why would the distributor need switched out?

I hate fuel injection :crazy: I grew up with carbs and understand them. It's just that simple for me....I've seen it done so I don't think unless I get crazy with a high rise intake and spacers it should fit under the hood. :thumbs:

you're starting w/the wrong Vette.......should have bought an older model equipped w/a carb. if that's what you like.....

This one basically fell in my lap....I took it in as a trade on a snowmobile....But if it was a case of buying what I really wanted, it would have been a split window big block.

Be very careful with the transmission TV cable. Carb swaps require dedicated, specific brackets, and careful TV linkage tweakings to allow the trans to remain alive. If the tv is wrong, trans will eat itself up quickly.

:thumbs:

I understand; maybe sell it and buy something else?

Thanks for the tip....I work in a prototype shop, so I think if I switch over the brackets and cables will be hand made...we did all the prototype cables for the Dodge Challengers.

63
 

So when are you buying the 63?:lol:

Happy to help. Most carb swap guys do not realize it is a throttle valve cable, and not a kickdown cable like the old turbo 350's.

Not a big deal to get them set up properly, but overlooked often.
If I can help, let me know.

I like the car... I don't see many Gold 85's or any other years for that matter. I already have put on a ported and polished plenium with bigger runners and a set of Hooker ceramic headers and stainless steel magnaflows...not to mention the ZR1 wheels and recovering the seats. I like being able to work on the car myself and I can't work on the fuel injection....My grandfather worked at holley for 40 years and he told me that the reason they came up with EFI is so you can't work on it.

When they fall into the 30 grand range:D

Your Pro Mod/Top sportsman in the avatar?

only 1400+ gold ones were produced according my stat sheet...

No. It belongs to a friend of mine. Andy Jensen, of Jensen Engine Technologies.

He (actually his turbo combination) was recently tossed out of pro mod when he set the 1/8 mile recored at something like 3.96.

My Buddy runs the old Mike Janis Cobalt. :cool:

I hope you really don't believe what you just said? If you understand fuel delivery in any way you would understand how unbelievable that statement was.

Let's see....carb rebuild by me about 30 bucks:D New fuel injectors $250 is on the lower side and it will take all day...now lets talk about the computer.:willy: I have delt with fuel injection one other time and I hate it :( It's a huge pain in the a$$... If fuel injection is so easy why is it that Harold Martin(The man that has all the patents for EFI at GM) can't make it work on his racecar?

I swapped out my EFI setup for a Holley 750 & Performer intake, and the RPMs pick up a lot better, especially 3k-5500, but because it's not an RPM intake it falls off after 5800. Don't know what your gears are, but I have 700-R4 w/3.07s and torque is plentiful all over the powerband. I'm considering a port match & portwork on the intake this year.

The main difference between the EFI and carb is drivability - it starts rough until it warms up, may be in part for the cam, but I know most carbs have trouble in the cold. I lost about 6MPG on average, down to 14 in city and 17-18 on highway. It really depends on how many RPMs you're hitting, I cruise around at over 2500 in the city so that may be why it's so low for me. :P

If you don't like EFI, and you like tinkering with carbs, I'd go for it if you're sure that's what you want. I haven't had any problems since the swap last year, and parts for the whole setup were ~$500. It's a lot cheaper to maintain a carb than all those damn sensors with the fuel injection..

tpi
 

I like my tpi. :cool:

Corvette Mike

Your cruise rpm at 70 mph should be approx 2000 rpm. Did you get your lock up converter wired properly?
If not your trans will be running 20 degrees or more hotter at cruise speeds.

I carbed my 84 for a couple of years and went back to fuel injection (superam). Car ran well with a Holley double pumper. Main problem was fuel perculation after shutdown. The hood seals so well that after shutdown, the engine compartment was so hot that fuel would perculate out of the carb into the venturis. I had to cut these ducts in the hood to allow for engine cooling.


http://i539.photobucket.com/albums/f...ch11-16-08.jpg

If the carb is easier for you and more affordable, then that is the way should definately go. Sorry to hear that he can't make the fuel injection work. I can tell you that I have raced a fuel injection C4 for years and along with many others, have seemed to make it work just fine.

http://www.autoimagery.com/store/cgi...ch=witherspoon

I had the same issue on mine so I had to remove the hood seal to let the heat out.

I can't even get the back bolt on the drivers side bottom of the runner out:( I have tried swivels, extensions and I don't see how to get at it without removing the wipermotor. I by no way am saying one is better than the other and would like to make the TPI work but :willy:
http://forums.corvetteforum.com/c4-t...take-swap.html

I'm not down the street, but I am local as you can see. If there is anything that I can offer, let me know.

Use a ball socket 6mm allen on a 1/4"" 6mm socket. I cut one and made my own.

6mm allen will work on a 40 torx bit?:o

Did any of you have carb/air cleaner to hood clearance issues?

You have a PM

Joe

http://forums.corvetteforum.com/c4-t...highlight=carb

http://forums.corvetteforum.com/c4-t...highlight=carb

http://forums.corvetteforum.com/c4-t...highlight=carb

http://forums.corvetteforum.com/c4-t...e-to-carb.html

Because the spark advance on the TPI one is controlled by the ECM

I never thought about that. Learn something new everyday :thumbs:

Weiand Stealth intake,will work and a few others.

book
 

Here is a good book to help anyone understand fuel inj.

http://i524.photobucket.com/albums/c...emikel/007.jpg

From my personal experience with carb and EFI I think they both have their pros and cons.

EFI is great because of the gas mileage and ease of tuning without taking anything apart like the carb, I know this is more easily achieved with newer EFI systems. The carb is simple yet effective, period. Out of all the cars i've owned my '77 Chevy C10 was the most reliable, never once did it refuse to start unlike EVERY single newer car i've owned.

IMO the early EFI systems like the TPI are garbage next to a carb in terms of reliability and power. If I didnt have so much invested in the TPI I would switch no question. However, I would rather transplant an LS1 or something of that nature instead. More efficient than any previous system.

I think this is an OBD-1 problem, OBD-2 reports exactly what is wrong, spark plug 3 misfire, compared to misfire. All OBD-1 tells you is something is wrong in a circuit, making troubleshooting hard compared to the latter. My TPI is throwing a bunch of timing into the mix and causing pings when hot, but doesn't report a problem, mystery problems. I am putting a normal HEI back in my car, but finding no room for the vacuum advance for adjustment. My injectors are so clogged I have to run 49 PSI of fuel pressure to make it idle bad, lol... I have new injectors for it, but haven't installed them. My car is down to 12 MPG.

Sometime back I saw a thread on a guy that took a carb and mounted on top of a TPI plenum .... was a 3rd gen f-body board I believe. Not sure if it was photochopped or what but was funny to look at. whether it ran I do not know, I believe he got it off ebay, but hey yout the best of both worlds like that, long runners and a carb without electronic hassles hahaha

Sounds like a Chrysler long ram

http://www.300f.com/ram01.jpg

Where do I get one?

I got mine at Barnes & Noble.

a 'must have'

Well, nothing wrong with EFI and nothing wrong a carb either. Folks go ballistic if you want to put a carb on something. They are easy and they are cheap (all things considered). Yes, you might spend a few bucks getting there but when its done, ez pz.
So back to the original issue, you will flow more with a new intake and carbs. The nature of TPI is it wasn't meant to breathe at high rpm. It was built for low end grunt. Can you get EFI that will breathe at higher RPM? sure but get out the check book and learn how to program. For most of us, carbs are in fact easier and ultimately cheaper as we can do it ourselves. Having said that, EFI is efficient, takes no warm up, has good reliability (when newer) and makes good power. Dont pick on a guy if he likes carbs. Especially since they are better looking (the carbs I mean).

I bought my car with the intent of putting a carbureted motor in it. I like the look and the suspension of the C4 much better than the C3. I have built and owned many early muscle cars and I have wanted to build a carbureted C4 for a long time but emissions in the big city always held me back. I moved out of the big city and now its “go time “.

If you're going to go backwards in technology, why stop at a carburetor? Why not just go all the way back to a horse and buggy?

Sure, if you go through all the hood hacking hassle of putting on a good intake and carburetor, you will pick up horsepower, but it will be at the expense of low speed torque which is one of the things that makes a C4 fun to drive.

I've messed with carburetors for over 40 years, and quite proficient with them if I might say so myself, but I wouldn't rip the L98 TPI off my Vette for all the corn in Iowa.

All that said, it's your car and you have the right to do with it as you please.

My $0.02,
Doc

no hood hacking...Victor JR with the right air cleaner base fits under the stock hood.

Going from carbs to fuel injection takes some study. Excellent book recommedation. I respectfully submit some 6 to 8 circuit carbs are not simple at all. They may operate on simple physics (pressure differential) however after you add circuits for air conditioning, secondary throttle plates, acceleration, transmission functions, timing, etc etc. Not so simple. If you can fix carbs, you can fix fuel injection. I grew up helping my Dad at his automotive garage and saw the range from 2 barrel carbs from 1950 to the 70's in trying to make them meet emissions standards. After you read a couple chapters in various books, you'll be on the internet helping people solve various problems.

Trust me. Spend a few hours reading a few chapters per night, and you'll be a expert in two fields.

Enjoy your car.

dlmeyers

:iagree: There are many agruments for FI and for carb, but don't make the the choice based on not wanting to learn FI.

Just curious if you have no smog laws that dictate what you can/can't have on your cars and yet complain TPI cant run at high RPM why not just buy a single plane EFI manifold/miniram and so on? Carb's suck in my opinion hell I'de take CFI over a carb any day.

whats so hard to understand about and maintain fuel injection? The ecm diagnoses most any problem associated with it.

ditch the TPI, buy a single plane efi manifold, buy an elbow and mount your throttle body to it. That should get you the higher RPM's and the lowend torque of port injection. Probably cost you not much more then using a dinosaur carb.

Yes, carburetors are easily understood with a little reading. Once you understand the basic subsystems of a carburetor, you can dissect and figure out ANY carburetor.

For me carbs are a mystery.....computers on the other hand I feel at home....laptop,cable,software... easy....plus if you want you can have different tunes in your chip and switch at will.

hello, just wondering if you are still willing to talk about swapping to a carb from tpi, I am having trouble with tpi fuel delivery and am thinking about a swap to carb.... thanks

Should start a new post about carb swap if you can't find what you need through SEARCH.
Have a look ;
every aspect of carb swapping has been covered over last 10 years.

FWIW
http://forums.corvetteforum.com/foru...s-or-more.html
Not supposed to bring back up any threads that has been dead for more than 45 days;
this one is 2 1/2 years old

If anyone is interested, on the thirdgen home page there is a tech articles link on the left side of the page, go to that and there are two conversion tpi to carb articles, one very detailed with pics (it is a link to offsite) and the other more basic for a more skilled and experienced mechanic / installer. I looked here but couldnt find anything as good as these two articles, maybe someone who is looking for info on doing the conversion will like these two articles.