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MG MGA - Pre engaged starter for early 3-synchro MGB engine

I am looking to buy a high torque pre-engaged starter motor to fit my MGA.
It is for a 5-bearing 18V engine which has the EARLY 3 SYNCHRO ENGINE BACKPLATE (WITH CRANK OIL SEAL) and matching smaller diameter flywheel. I plan on fitting this engine n the next few weeks.

Why? Well my inertia starter struggles at times to spin my outgoing tuned 3-bearing 1850cc engine, particularly when it is cold.

The pre-engaged starter subject is a bit of a minefield and I have seen quite a few ads for starter motors that apparently will fit this engine.

Some have solenoids on the top and some on the bottom and I wondered which one of these fits into the MGAs engine bay the best.

Is there a difference between a pre-engaged starter motor and a high torque motor? Or are these different names for the same thing?

There is also a big difference in the prices too, they range between £80 and £200.

I would appreciate any advice on this.

Thanks

Colyn
c firth

Colyn

This is mine in my 1800V high starter position. Works great.

http://www.mgaroadster.co.uk/hi_torque_starter_motor.htm

Mine is a high torque, having reduction gearing built in. The pre-engaged bit refers to the driving cog driving forward to engage the flywheel before any rotation takes place. So one of the many benefits is no more whirring and gnashing of teeth. The other benefits are explained in my link.

Steve
Steve Gyles

Thanks Steve,
I think you have the later 4 synchro MGB backplate on your 18V engine and I am (fairly) sure that it uses a different starter.

Colyn
c firth

Colyn

No. I used a 1600 back plate with hi starter. I certainly bought the MGA bell housing for my T9 gearbox. I milled out the plate to take the oil seal. I bought an MGA specified Hi-torque pre-engaged starter.

Steve
Steve Gyles

PS. I got my starter from Auto Electric Supplies. It is a Powerlite RAC410. With vat and delivery (£0) in 2010 it cost £168.30.

http://www.autoelectricsupplies.co.uk/

Steve
Steve Gyles

I will give autoelectrics a call thanks Steve, on their website they have three high torque starters listed to fit the various MGB backplates.

Hopefully they will tell me which of them I need, I think the main difference is in how many teeth are on the starter motor pinion.

Cheers

Colyn
c firth

Colyn,
Yes, I think it is 9 or 10 teeth on the Bendix.

Regards
Colin
Colin Manley

Hi Colyn.
I've just completed installing a late 18V engine into my MK II.
The engine is standard capacity, 1798, but the head has been worked and the block decked to bring the compression ratio to a carefully measured 9.8:1.
We used the 18V backplate which of course has a seal, and eccentrically enlarged the starter motor aperture in the backplate to use the original MGA starter motor in its original MGA location. The flywheel on the 18V engines is a larger diameter than the MGA flywheel, so the 18V flywheel was machined down to MGA size and fitted with an MGA ring gear.
My original MGA starter motor has no difficulty whatsoever spinning over my 18V engine, despite the larger capacity and high compression. Perhaps your starter therefore may need to be checked and refurbished rather than needing to be replaced altogether.
T Aczel

You may be right Tom, although I suspect that my occasionally sluggish starter is sometimes a little handicapped by the single 12v battery I have, which looks like it would be more suitable for Fiat Punto.

I may try it with the inertia starter to begin with to see how it copes.

But I would still like to find out which high-torque starter will fit my engine in case it doesn't.

Thanks

Colyn
Colyn Firth

Hi again Colyn.
I run a single battery too. In my case an "Odyssey" dry cell (gel) battery. I don't know if you have them in the UK. They're an American product. I have one in my MGA and one in my MGB. They're about 2/3rds the size and weight of a single conventional 6 volt lead acid battery. A bit pricier than a conventional lead acid battery but my last Odyssey only had to be replaced after 13 years. My neighbour's after 16 years. No trickle charger in either case, though I've now bought Cetek trickle chargers for both my MGs, as advised by my local Odyssey stockist.
Can't advise you regarding alternative starters except to say that I've heard mixed reports regarding the durability of some of the after market gear reduction starters. An eBay search will locate many offerings, but the quality of the shiny items shown is impossible to judge. I've heard of several that were fitted to various MGs that suffered premature failure. I suspect if you go onto the MGB section of The MG Experience, and do a search for "gear reduction starters" you'll find quite a few comments. A search in the MGA forums of the same site will likely give you a guide regarding which of such starter motors might suit an MGA application.
But even though they're lighter and more powerful and presumably draw less current, as I said, I've not sensed the need. After all, a conventional starter was also quite strong enough for the MK I MGB models, although ring gear wear is an undeniable problem with this earlier design of starter motor.
T Aczel

Colyn

I went down the pre-engaged starter route for similar reasons to yourself; occasional sluggishness and the whirring and gnashing of teeth - wearing the starter ring. When the standard starter was turning well it was absolutely no problem. My decision was based more around the crap starter switches we get nowadays rather than any other factor. With the pre-engaged system the starter switch only takes a maximum of I think 5amps to operate the solenoid. The main power feed bypasses the switch, although it uses one of the terminal posts for conveniently connecting to the battery cable, so there are no issues with high resistance in the switch arcing/burnout etc.

Steve
Steve Gyles

I have a Numbers of Original starter Switches on stock in case another one goes. But I have only needed one replacement in over 25 years of ownership.
dominic clancy

The crappy new replacement switches don't fail because of arcing. Failures are due to break down of sub-standard insulating parts between the pull shaft and contactor plate, making a dead short from battery to ground through the pull shaft. Original switches have a Phenolic grommet molded in the center of the contactor plate that will never fail. My original switch lasted 58 years and 445,000 miles before it succumbed to dirty contacts.
Barney Gaylord

This thread was discussed between 24/02/2016 and 26/02/2016

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