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fuel injection for 1275?

Posted by 59traveller 
59traveller Avatar
Alex Wilds
Columbia, SC, USA   usa

I have seen a photo of fuel injectors on a 1275 in Vizard's book, and know that some Coopers were so fitted. I reckon injectors from later cars can be adapted. Sure, I like simple SU's and a dizzy just fine, but I am curious. Has anyone ever fitted injectors to a spridget? Is it a crazy thing to do, wildly expensive with zero gain?


59 Traveller
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John-Peter Smit
Toronto, Canada   can

a few folk have gone with mega squirt and love it! the guy in the motorcycle shop down the street wants me to through a goldwing injection system on my 1500
Billy Aintsayin'
south, USA   usa

VE tables have got to be the same unless it'll self tune.
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Kerr Avatar
Norm Kerr
Ann Arbor, Mi, USA   usa

the mini MPI system used from '96 ~ 2000, on the A+ engine works pretty well, but requires that pretty much everything be changed in order to adopt it (from the crank, on up). It was developed by BMW, right after they bought the company.

the mini SPI system used from '91 ~ '96 is more of a throttle body added to a "familiar" A series (though, still an A+, but not as much, mechanically, was changed).

The downside of the SPI is that it is not very sophisticated, or use as many "modern" parts, so, electronically it can be a real bear to troubleshoot. The MPI uses some modern car diagnostics and parts. Both systems are quite complex, and stray electrical issues can really cause heartache. The support for both of these systems is improving, but for years, folks with SPI would ditch that for an SU when hard to find electrical sensors started acting up.


Those are the two "factory" options. Custom injection abounds with choices, all of which boil down to just how deep do you want to go? To get full advantage, you would like to develop a custom cam, intake, timing profile and so on.

Popular Classics did an article in the '90s where they simply put a throttle body from a Ford Escort (or Contour) onto an MGB and it worked very well for them. In that case, they really just went for the "better fuel atomization" and left it at that (no real engine modifications).

Norm
mjamgb Avatar
michael anderson
NORTHERN NEVADA, USA   usa

If you install a plenum or TB style injector with Lambda feedback (o2 sensor) it can make life much much easier and you can "tune with a dial" the power/economy (within limits). The MegaSquirt system coupled with MegaJolt (ignition) will offer the greatest "bang" for the buck.

Doing the injection and mapping the fuel (with feedback loop) is not too awful and can be done nearly all bolt-on, but the MegaJolt will require some fiddling with spark timing methods... all the parts are available in the aftermarket since lots of racers use various forms of these systems alreacy (where sanctioned).

I have this kind of thing in mind as well, but it isn't on the "short list" by any means!!!
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jeffnoll Avatar
Jeff Noll
Western MA, USA   usa

One of the things I like most about my Midget is the feeling that you are in a sense connected to the entire car. Push the peddle down and you know you are yanking on a cable that at some point basically just opens a valve more. Turn the steering wheel and you know you are directly turning the car, same with brakes.

Sure, you can go buy a Porsche and zoom around the corners at 3 times the speed, but are YOU really doing it? Not so much. I like my carb and all the other mechanics despite their short comings. Anyone wanna trade my 911 Turbo for a chrome bumper midget tongue sticking out smiley
Robert Kirk
Davenport, Iowa, USA   usa

To carry on the theme from Jeff. I was rather taken aback when my diesel mechanic inmfomed me the "fuel" pedal was just a sensor tied to the computer. Never thought about it but being electronically injected a cable would pull/push nada....

Of course there are really few "thrills" missed in driving a 3/4 ton diesel Suburban, unless you are trying to top Loveland Pass outside Denver and the Turbo sensor takes a dive...couldn't even accelerate going down hill what little of that I met....



Regards,
Robert Kirk
kirkbrit@yahoo.com
563 323 1017
Moss distributor UK importer
Beat or match any retail/delivered quote

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NOHOME Avatar
P P
O, Ontario, Canada   can
1967 MG MGB GT "Maggie (GT From Hell)"

Go buy a set of thorttle bodies from a snowmobile or big motorcycle. Read up on megasquirt injection and off you go. From what I understand, it becomes a hobby unto itself once you get into it.

The downside is a car that starts immediately, iddles rock steady angets better performance andmileage.


I mean, where is the "charm" in that?
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59traveller Avatar
Alex Wilds
Columbia, SC, USA   usa

Thanks, folks for the very good info and ideas. My car, a 59 Morris with all spridget running gear, is even more primitive than most of yours, like mechanical clutch linkage, and I love it because of its spartan qualities. But as my one and only daily driver I am thinking a little bit about the environment, economy, and reliability. I do not want to fool with the distributor, just to find the cleanest, most efficient way to get gas into the engine. I will check out some of the options, perhaps simply because I am running out of stuff to fix on it.
Walt Beermann
Aurora CO, USA   usa

I am rebuilding a 1972 MGB and I am planning to convert to fuel injectors. I have bought and disasembled throttle bodies from a GSXR 600. I have already fabricated the spacers and linkeage to control both throttle bodies. That was the easy part, now I need some help on what vacumm hoses are used and conected where. I have read pros and cons on venting the engine breather pipe through the throttle bodies to burn up the gases, but this will leave an oilly film behind. Do the holes left after removing the chocks just get pluged? There are small vent outlets on the the throttle bodies, where do these get plug into, the top of the intake manafold. I am building my own fuel rail which has a regulator on the exit side. I need help on all the hose conections. Will get to the ECU later. Reading all about the Megasquirt. This is a learning experiance on this project for me, but very interesting. Need help.

Your MGB friend,
Walt
nimblemotorsports Avatar
Jack Murray
Sacramento, California, USA   usa
1971 MG 1100 "MGeo"

In reply to a post by 59traveller I have seen a photo of fuel injectors on a 1275 in Vizard's book, and know that some Coopers were so fitted. I reckon injectors from later cars can be adapted. Sure, I like simple SU's and a dizzy just fine, but I am curious. Has anyone ever fitted injectors to a spridget? Is it a crazy thing to do, wildly expensive with zero gain?


59 Traveller

you can certainly adapt some throttle-body-injected setups without too much complexity,
but then why not just ditch the 1275 for a complete newer EFI engine?
And get a 5-speed trans too.
mjamgb Avatar
michael anderson
NORTHERN NEVADA, USA   usa

Jack, Jack, Jack... That is entirely off base and out of the question. If you will review Peter's post, I think he puts it quite succinctly.

You really need to run it through a 10-foot convoluted rubber tube for proper noise reduction, too!

winking smiley
Walt Beermann
Aurora CO, USA   usa

Walter Beermann [ PM ]
Walt Beermann
Aurora CO, USA Posted: January 02, 2011 06:20PM
Registered: 23 days ago
Posts: 1


I am rebuilding a 1972 MGB and I am planning to convert to fuel injectors. I have bought and disasembled throttle bodies from a GSXR 600. I have already fabricated the spacers and linkeage to control both throttle bodies. That was the easy part, now I need some help on what vacumm hoses are used and conected where. I have read pros and cons on venting the engine breather pipe through the throttle bodies to burn up the gases, but this will leave an oilly film behind. Do the holes left after removing the chocks just get pluged? There are small vent outlets on the the throttle bodies, where do these get plug into, the top of the intake manafold. I am building my own fuel rail which has a regulator on the exit side. I need help on all the hose conections. Will get to the ECU later. Reading all about the Megasquirt. This is a learning experiance on this project for me, but very interesting. Need help.

Your MGB friend,
Walt
mjamgb Avatar
michael anderson
NORTHERN NEVADA, USA   usa

What I know specifically about GSXR throttle bodies you could fit in a thimble and have room left over for your finger.

However, that rarely stops me from rendering opinions winking smiley

I would indeed vent the crankcase. My initial thought would be to do it to the cross-over tube between the intake runners a'la early MGB and use the "mushroom" style PCV valve.

If by "chocks" you are referring to the air injection ports, then by all means plug them. I used 1/2" long allen head grub screws.

The vent outlets have me a bit puzzled. If they are fuel return lines then they should certainly be plumbed into your existing return line. If they are a source of atmosphereic pressure air for some inner working of the TB, then they should have access to filtered air, just like the throats.

You may or may not have a source of ported vacuum for your distributor. If not, you can have your distributor re-curved to take advantage of manifold vacuum and put another tap in the intake next to your PCV. Mr Jeff Schlemmer is the recognized authority on MG dizzies.

No other vacuum is necessary so any other vacuum ports should be plugged.
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