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MG MGB Technical - Distributorless ignition anybody?

Check this out.

Nah,,waste of time and money. Why bother anyway its far from original.
Iain MacKintosh

Why not? For those of us trying to improve on the originals to keep our daily drivers running as long as possible this is one way of elliminating one component that wears and requires regular parts and maintenance.

this looks like a fun winter project, I have two Bs to mess with, I may try it on one of them.
The Wiz

Parts are readily avaliable and the cost to build one doesn't look bad either. For those of us with worn dizzy springs and bushings this would make a reliable replacement with a potential for a boost in performance and fuel economy.
I am in the process of building a turbocharged B and need a way to retard ignition timing under boost, and as a plus this thing will do a rev limiter and another RPM related accessory function.


Megasquirt is what you need.

I just installed this for fuel injection on my B, and will be doing the ignition next. For ignition it can be controlled with manifold pressure and RPM from a table. You can simulate most any curves. What is nice about this is that you can start small and use it to keep adding more capability. The support is outstanding.

It is relatively cheap, and will handle ignition and/or fuel from a table. It is best to do one at a time. You could use it for ignition control as a start, and later as it suits you add fuel injection.

Megasquirt has been mentioned on this board before and I suspect there are a few people using it besides myself.

The web site is a bit intimitating at first, but you'll get over it in no time. What you want is the Megasquirt I Ver 3.0 with Megasquirt Extra firmware installed (MSI v3 & MsnS-E)


werner haussmann

Very intertesting Werner. I've been following the Megasquirt stuff on and off but have to confess I didn't quite get past the intimidation stage on the website. Are you still using the distributor as the trigger? What's your verdict on the benefits?
Steve Postins

I have done a good bit of investigating on the Megasquirt. I don't want to mess with the fuel injection aspect. Between the rising rate regulator, swirl pot, high pressure pump, and return line and the problems associated with injecting the siamesed ports I decided not to inject my car. My intake tract for the turbo is built to accept a HIF6. I have no concern about the fuel aspect.

I am planning to run this DIS setup, I just wanted to share my findings with anybody else who may be interested.
I'll be sure to provide pictures to everybody when it runs.


At this point I have the Megasquirt for fuel installed, running but not yet completely tuned. It is relatively easy to operate with the provided software. I'm running it with a TBI (throttle body injection).

Once I have the fuel tuned I'll resize the throttle body (smaller) and then I'll add the ignition using the Crane optical trigger to feed the Megasquirt. I likely will not get to it for another month.

As I've indicated in previous threads, moving to Fuel injection does not provide significantly more power, but it does provide better tune. With the controlled ignition, I'll also be able to simulate port vacuum which I've never been able to do with the HIF carbs I had.

I expect a better running car and mostly learn an awfull lot about EFI.

The difference between this setup and my two previous conversions with a Bosch setup is that this setup does not require an air flow meter and therefore will look a bit simpler and more tidy. It uses MAP (manifold absolute pressure) The down side is that any change in the head or significant wear in the valves will require a retune.

werner haussmann

Werner, I am very interested to hear how your setup runs once it is tuned. Are you using a crossflow head or the reverse flow? I have heard the reverse flow heads have problems with running 2 cylinders lean when they are injected. I think it was 1 and 4 that ran lean due to the valve timing.

The account I heard about was using port injection and not a throttle body. I dont' expect the TBI setup to cause the problems of a MPFI setup.
Moss had been working on a TBI setup at one point and TWM Induction had DCOE throttle bodies.

There was a line of comments on this board several years ago, re a conversion of The MGB induction system to fuel injection by adapating a Volvo throttle body system. 1/ it was a lot of work 2/ Driveability was better, but there was no increase in power. A tuned individual port injection system isn't feasible because of the siamese intake ports.

There are reports of several people using after market injection kits with the five intake port alloy head.

The injection system advantage is that you can get a better power curve than with a carbureted system. Particularly with a hi duration cam. The max output for a pair of webers isn't supposed to be much different than the tuned injection system. The driveablility is supposed to be better with the injection system.

Getting it set up to provide the driveability etc is the hard part.

Barry Parkinson

I am using a Throttle body injection. As a result I have not had any problems with the siamese port head. The engine is standard all around. A five intake port head would allow multiport injection and the advantages of a dry intake manifold.

Earlier this year someone was going to try to do that with a Bosch Jetronic system.
The Bosch system is much easier to set up. The MegaSquirt system allows full control of fuel and ignition, but is harder to set up. Ideally is best set up with a dyno.

Using port injection with the siamese port head is possible, but requires custom software. I am not ready for that. Possibly sometime in the future Megasquirt might support that???

I am aware of the Moss setup, but they keep delaying it. I don't know if they will ever release it. I've done two Bosch setups (also TBI). The Bosch setup is relatively easy to implement since it is already 'tuned' and you can use the donor car wiring harness. The Megasquirt is a bit harder and requires building a harness. Throttle body, fuel deliver etc is the same for both.

Once I get the Megasquirt with ignition ocmplete, I'll write it up. The Bosch setup for a '74 has a picture here and has been published in the past. Note; the throttle body is a 1.75" that is too large for this engine. Throttle body sizing is not the same since there is no venturi.

werner haussmann

sorry that is 'four intake ports' in the first paragraph
werner haussmann


I know two chaps that have fully working EDIS up and running in their B's. They can plug a laptop in and change the ignition map, even on the go. All in the parts cost about the same as a new dizzy (at least in the UK) so it is an ecomomical option and will prevent issues in the future with dizzy shaft or spring wear that normal EI does not get around. They use the system in Robert's first post. They use a throttle position sensor. One is on a 65B with Weber carbs and the other is on an 80B with HIF carbs. Both are fast road engines. I believe that they are having photos taken and being interviewed this week by someone from MG Enthusiasts magazine with a view to an upcoming article on the subject. There were quite a few teething problems, particularly with interference IIRC.

If anyone wants more info drop me an email and I'll pass it on.

I D Cameron

If you want to run injection on a B engine it would be worth looking at the midget project written up on the Emerald web site.

They deal with the issue of siamies pot heads, where the induction intervals have to be considered so as to ensure even mixture. What they do about a swirl pot may be of interest also.
David Witham

This thread was discussed between 12/11/2005 and 14/11/2005

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