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MG MGB GT V8 Factory Originals Technical - Carb or FI with the Chevy 3.1?
|I know this topic has debated before, but I can go one of two ways with the 91 Camaro donor car I bought. I can go the carb route and pull the drivetrain and leave the wiring, etc. intact and sell the roller to some kid wanting to do a V8 swap, or I can remove everthing and try to make the FI system work.|
If I go the carb route I'll need a 2 barrel manifold, carb and distributor from an early s-10, etc. Simple and something I feel very competent to do. And the parted Camaro will be worth more if the wiring is unmolested.
The FI route will probably make more power and give better mileage, but I'm picturing a nightmare. And to make matters worse, the car runs rough at low RPMs so I'm looking at spending money just to get the Camaro running right before I pull the drivetrain.
I know there are special wiring harnesses that can be bought to make the FI work, but I'm on a tight budget right now. I'm thinking the wisest thing on my budget is to buy the conversion kit and search the boneyards for a 2 barrel manifold and distributor. I happen to have a rebuilt Weber DGV. Will this carb work ok?
I've read the archives a lot and I know everyone has an opinion, and I welcome them.
|Terry, since you are on a budget then I'd recommend going to the S10 carb and distributor. I've integraged the computer from a Camaro into my midget and based on what you say about your experience level that sounds like the best way to go. If you are tempted to go with the FI remember that you'll have to install a high pressure fuel pump along with a fuel return line to the tank, an O2 sensor in the exhaust, and figure out how to bypass those inputs that aren't used in the MG such as AC pressure. You'll also have to use the speed sensor from the transmission, so you'll have to figure out some type of drive for the speedometer, or do without. Either way, don't forget to modify the tach to read correctly with a 6, which I still haven't figured out how to do. There's a lot of information on changing them to V8 usage, but I haven't found anything yet on the components needed for a 6.|
|I went the carb route. I bought a new manifold and a 390 holley carb. Not cheap, but it runs great.|
I have over 30,000 miles of the car if 2 years.
I, too, felt more comfortable with the carb than the FI. I even had the wiring and still went with the carb.
I think the DGV will work with the S-10 manifold. It is certainly enough to run the 3.1.
I chose the carb partially because I was also using the auto trans and felt I had enough unknowns to play with.
I used an eletroic speedo from Classic Instrument and also one of their tachs.
|Thanks Bill, you've been a great help so far and I'm barely into this. Maybe if the Camaro was running properly the FI swap may be a good idea, but as is the carb route is looking better all the time.|
|I'd definitely go the FI route.|
Better running, mileage and starting.
Should be no big deal to get the existing engine tuned before you rip it out - maybe a dud sensor or some such.
Yes, it IS more fussing with wiring to shorten leads etc., but the results are much better. One touch of the starter and it starts - always!
If you need advice on the mods necessary to run the FI in your car - tank, return pipe, pumps etc., you can get it all here.
|Bill, I agree heartily with the drivability side with the FI, it's one of the reasons I chose to keep it for the Midget even if it meant a lot of modifications to the car. My advice for Terry is mostly based on his budget concerns. I don't remember when GM changed the ECM style from the ones with seperate chips to the newer style that can be flashed, but at least the early style can be 'coded' by the average guy with a jumper, the later style need a special code tool. Either way I'd advise Terry to get the Camaro coded to find out what's wrong before I take it apart, a lot easier to find out now than later. |
Terry, I don't think the Weber will work, as I remember is't a two barrel with one primary and one secondary. You'd really need at least a standard two barrel if not the small Holly four barrel to get the best performance.
|Steve: what did you do about the pulley system, and what did you use for the tranny mount?|
I am All for FI and usually give a big long speach about how you regret and all that...
BUT because the fellows above have already done this, I will ask you to make Sure that you read those posts of theirs very well. I agree- FI is the way to go.
That said and playing Devils advocate, there are a few issues to bring up AND use some of your explinations:
You have the highest manifold (RWD 85-92 2.8/3.1L)which needs lots more work to fit below the sheetmetal. I don't care for that manifold for too many reasons that if you dealt with it, you would agree its a bit difficult.
Wiring to strip out of the parts car would be a bit much making your car possibly worth more to a kid thus getting about $100-200 of your investment back.
This is VERY IMPORTANT. This advise is for you and others in your EXACT position. Because you are Really on a very Tight Budget and you are not planning on purchasing a $$ lower manifold, $$$ upper manifold, $$$ carburetor and $$$$$$ fancy new distributor and ignition system- but plan on sticking to a 1982-1984 S10 carb, manifold and stock distributor/ignition system, it would be okay to go carburetted.
-Going with the big carb/igniion system is VERY expensive!
I keep these in stock as often as possible- a good stock manifold, carb and distributor system that have been tested BUT because you are on such a tight budget, you need to pull one from a U-pick-it yard and test/clean/repair it yourself. From some yards, you can get these for as little as $75 for everything which is less then I can offer them for untested.
Would you regret not having FI? Only if you drive someones conversion with FI! If you vow to never drive a FI version, you will probably be happy. Just make sure to keep all the FI stuff so if you ever decide to go that direction, you have the parts.
|BMC Brian McCullough|
|Brian: if my FI system is the worst to work with, wouldn't it make sense to sell this setup and later down the road when I have move money and might decide to do an FI to buy a more desirable unit?|
Most of the parts can be used but the manifold is too tall. This can be trimmed down and the motor mounts trimmed up a bit with lots of trimming, it will fit. As for BHP, reliability and so on, its a fine setup for the 3.1L
A second choice is to alter a 3.4L UIM and use it with the stock lower (LIM) for your motor. That and your stock injector rail.
The SFI system complete is not really an option.
It is almost always true on any given build year for the GM 60 degree V6 that you can almost always backdate these motors but you can never update them- A 3.4L Camaro can be backdated with the MPFI, TBI or any carb. A 3.1L can be backdated to TBI or carb. A carb motor is rarely ever updated except for way back when- say the rare race motor in the early 1980's. Okay, a little off topic.
Another choice is going with TBI from a 85-92 S10 2.8L and using the 4.3L injectors. The computer and wiring from one of those S10s can also be used, as well as the automatics and so on.
If you plan to build lots more power in the future, the current 3.1L motor you have with a carb is a perfect step and when you can afford it, get a 3.4L with the much easier to fit SFI system. You can build a 3.4L which has the same crankshaft as the 3.1L with 3.03mm larger bore, add a few go fast items, give it a porting and get quite a bit more power at the same very reliable level of use.
|BMC Brian McCullough|
|I bought the whole package, engine and tranny fron the wrecked car. I used the stock pulley set up that was on the engine. The trans mount is the MG cross member, modified slightly with a stock 700R4 mount and relocated toward the back of the car slightly. I did have to put a bulge on the passengers side of the tunnel. The bulge dos not show under the carpet. I also had to cut out the driveshaft loop at the back.|
My AC compressor, alt , and carb stuck up through the hood, so I put a scoop on to cover them. YOu can see my car at Britishv8.org I have changed wheel since the picture was taken, but it will show the scoop.
This thread was discussed between 16/04/2007 and 18/04/2007
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