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MG MGA - SU carb set up

Hi All,
I've decided to leave the Flat Earth society & convert the MGA to Neg. earth. Before I do that however, the cyl. head has been on & off several times in the last 2 years & the carbs are now all out of kilter. Does anyone know of a reliable fellow in the Birmingham area who balances, adjusts & sets them up please? I've got a colourtune kit but the last time I had them set up, the bloke used a Trumpet? type contraption. Also, I've just ordered an electronic ignition kit with leads, coil etc. The Dynamo is knackered, hence swapping to Neg. Earth. What size output Alternator would I need? I can fit everything but I'm that useless at electrics I'll have to get someone to connect them as I can't take a chance at blowing the car up. Any help or advice would be greatly appreciated.
Thanks,
Ray.
Ray Allden

Ray

I can't help you with knowledgeable people in the Birmingham area, but being the home of car making there should be plenty of experts!

I will start with the alternator. What engine do you have - 1500? The reason I ask is that the 1500 block is not tapped for the rear alternator brackets - the alternator being shorter, but I believe suitable brackets are available or you can fabricate one yourself. I used a standard MGB alternator that has proved entirely satisfactory over the last 15 years.

Wiring the alternator is not difficult. We all have to start somewhere! These two links may help:

http://mgaguru.com/mgtech/electric/ac101.htm

http://www.mossmotoring.com/generator-to-alternator-conversion/

Steve
Steve Gyles

The "trumpet" type device would have been used as an aid for balancing the carbs (airflow) on the throttle stop screw. The Colourtune is used as an aid to set the fuel/air mixture (with the jet adjusting nut).
N McG

There's a good chance that the rear bracket off a Mini will do the job. The (early?) A-series block was always tapped for a generator.

If you take your time adjusting the SU's is very doable, even for an amateur (like myself). When you Google adjusting SU carburettors you'll get numerous results.
I liked this one:
http://www.mg-tri-jag.net/tech16.htm
Willem van der Veer

Many thanks all. I've managed to find a guy who comes to your house & carries out a full engine tune with carbs. etc. Found that an early Renault Clio alternator has a large bracket holding on the alternator so I'll try to modify this & let you know. I couldn't find one at all that uses a "V" type pulley so I'll try to fit the dynamo one if poss. Many thanks for the link Steve, very helpful although I can blow a light bulb fitting it. I found the phone number of the guy who originally connected up the MGA after the rebuild. I've got a standard 1600 engine fitted, does that mean the standard MGB bracket fits with no mod's?
Thanks again.
Ray Allden

Ray

I think the 1600 block, like the 1500, only has two rear holes tapped for the generator bracket. The 1800 engine comes with both the generator bracket holes and the shorter alternator holes. You will probably need to fabricate a suitable bracket or, using the existing bracket, use some tubing as a big shim and a longer bolt - not an ideal engineering practice, but it works. I think the Moss link shows this proceedure.

Steve
Steve Gyles

I think the alternator bracket 12G1053 ( 1275 midget etc ? ) is the standard method for mounting an alternator.

Barney's mgaguru website as noted by Steve has all the info on changing the wiring.

Jim

J N Gibson

Ray, if you fit a lucas acr alternator I would go with either a 17 acr or an 18 acr.
The 17 acr gives 38 amps / the 18 acr gives 43 amps. This is double the amperage produced by a generator.
I bought a early mini Cooper rear alternator bracket from eBay, was
only a few pounds, fit s a B series engine perfectly.

Also if you follow mga guru s fitting instructions I would recommend that you opt to wire it up directly and not using the old control box to connect it. I connected the alternator output wire directly to the starter switch positive terminal.

It is easy to get a poor connection if you use the old control box screws connections as a connecter block and the alternator voltage output can then go far too high and cause damage.
Also the output wire from the alternator needs to be much thicker than the original wire in the mga wiring loom so as to cope with the higher amperage possible.

Be glad to expand on this if you wish

Colyn


c firth

Ray, if you fit a lucas acr alternator I would go with either a 17 acr or an 18 acr.
The 17 acr gives 38 amps / the 18 acr gives 43 amps. This is double the amperage produced by a generator.
I bought a early mini Cooper rear alternator bracket from eBay, was
only a few pounds, fit s a B series engine perfectly.

Also if follow mga guru s fitting instructions I would recommend that you opt to wire it up directly and not using the old control box to connect it. I connected the alternator output wire directly to the starter switch positive terminal.

It is easy to get a poor connection if you use the old control box and the alternator voltage output can then go far too high and cause damage.
Also the output wire from the alternator needs to be much thicker than the original wire in the mga wiring loom so as to cope with the higher amperage possible.

Be glad to expand on this if you wish

Colyn


c firth

Many thanks again all.
Thanks Colin, please see below. I did buy an ACR one.
Jim, I'll have a look on EBay & see if there's one going atm.
Steve, I went with your advice & bought an MGB alternator. They supplied a bracket for the modification from Generator to Alternator but, it is as you say, only 2 small bolt holes so I will probably have to use a longer bolt & spacer etc. I fitted an "Accuspark" distributor, coil, leads & plugs last night but ran out of time to test so I left the battery on charge & am going out in a few mins. to try to finish it off.
I'm going to have to get someone to wire it though, I really don't trust myself with wiring.
Going to the Heritage Show at Gaydon on the 6th. July so I want it all sorted by then.
Thanks again,
Ray.
Ray Allden

This thread was discussed between 17/06/2014 and 25/06/2014

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