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MG MGA - MGB Rebuilt or Remanufactured Engine Recommendatio

The engine of my daily drive 1957 MGA is finally on its last legs, and rather than rebuilding the motor, I’ve decided to replace with an 1800 MGB engine and 5 speed gearbox, and if funds permit a supercharger.

I’m keen to get a good quality and fast (though not race grade) replacement engine, and I’m looking for recommendations and any advice I can get.

Living in Australia I have the added challenge of shipping costs and logistics if the best option is to bring one in from overseas, so any suggestions in this area would also be greatly received.

Thanks in advance for your help
J Dawson

Not sure how much in shipping you want to get into but I would recommend both Peter Burgess in the UK and also British Automotive in Novato, Ca. British Auto used to provide the tranny tunnel required for the conversion as well.

Good Luck,

Bayard
Bayard DeNoie

Would you be looking for a 3 main or 5 main , engine....
As long as you're looking, I would go with a 5 main...
I don't know why you think you would need a 5 speed...A 4-speed, with or without O.D., is suitable for most driving styles...and the standard 4-speeds are cheap, and plentiful....Syncro on all 4 gears, and capable of reaching 90 mph (140 km), with no problem.
You might also consider getting a good used engine, and rebuild it yourself....Very easy engine to work on IMHO)
Edward
Edward Wesson 60MGA

Thanks Bayard, will check-out Peter and British Automotive
Cheers John
J Dawson

Thanks for your comments Edward. I might have confused things by saying 5 speed, I was actually meaning the MGB 4 speed with OD.

I do a lot of city driving during the week and the existing MGA 4 speed box is fine, however on the weekend we want to do more touring, at the moment I can't keep up with traffic on the freeways and the poor car sounds like it is reving it guts out. Was thinking the 4 speed with OD would allow for leisurely cruising at 120KM for a hour or so, and the supercharger would give me some serious acceleration ;-)

Cheers John
J Dawson

John,
Gearbox combinations where extensively discussed in the recent thread "rebuild on '58 MGA coupe".
The 5 brg 18V engine is the strongest but also the most difficult to adapt. Suggest you get yourself a copy of Peter Burgess' book
http://www.pitstop.net.au/products/how-to-power-tune-mgb-4-cylinder-engines/
Also have a look at MGAguru page
http://www.mgaguru.com/mgtech/power/pp201.htm
http://www.mgaguru.com/mgtech/power/pp201a.htm
Mike
Mike Ellsmore

Hi john
Couple of points worth considering,
The overdrive gearbox won't fit the mga without some tricky chassis modifications to suit the rear of the o-d box. Some cutting, fabrication and welding. Fitting a 5-speed box would be much easier.
( Also, to the best of my knowledge, all mga 4-speed boxes have no synchro on 1st gear)

Even if you have your engine
performance tuned, it will still rev the same as it does now at the same road speeds. It will just get to those road speeds much quicker.
I would fit a 5-speed and keep your std 4.3 diff, this gives you slightly
better ratios on the 4 lower gears with an overdriven 5th gear for cruising. With the added bonus of synchro on 1st gear for driving in traffic.

The other option is to keep the standard 4-speed box and swap the 4.3 diff for a 3.9. This will make the engine rev less at motorway speeds but will reduce your cars acceleration a little, which may not suit you for town driving.

The mgb engine, even slightly tuned will feel great in your mga, a lot more torque available. It would be easier to find a 5 bearing engine than a 3 bearing which are quite rare. The general opinion is that the 5- bearing crank is stronger than the 3 bearing which may suit your plan to fit a supercharger. You will also need some different cylinder head work done specifically for either a s/c or carb induction.

You are looking at some serious investment here though John, here in the UK you would be looking at something like £5k to £6 ( plus labour charge)

If you do all this to your mga, can beg a drive in it?

Cheers
Colyn


c firth

I do a fair number of MGB 1868 stage 2 + 5 speed Ford type 9 MGA conversions - the whole job works out at £4000 including fitting - it is a very straightforward conversion that takes less than a day.
Chris at Octarine Services

Chris,
Do they bore an 1800 3 main to 1868s too?
or is that just for the 5 mains? Just wondering.

Ive got a 1800 3 Main with 3.9 gears and I think its a great set up that way...but if you do a lot of long highway travel get the 5 speed.
Steven Devine

Just to be clear, my reference to a 4-speed, was for the MGB fully synchoed 4-speed...Not the MGA gearbox....

I can't imagine that speeds up to 120 kmh+, would require anything else, as the engine will be running in the 3000+ rpm range, where it is really "happy"....
I do not think that these 4-cylinder power plants were ever intended to run efficiently at the lower rpm range, like a 6 or 8 cylinder motor.
I have nothing against the O.D. trannys, except they are expensive, and more difficult to find in good working order...(not to mention , more expensive to service).
Any 5 speed, will be more expensive, and more difficult to adapt....and based on your use, a waste of effort....
In addition, you will always be chasing parts, as service is required, since the power plant and the tranny were never intended to be mated.....
There is something to be said for convenience and ease of ordering parts, especially where you live....
I don't think that , for the most part, your gas mileage will benefit that much from the 5-speed....especially in traffic situations....(where you will always be in the first four gears anyway). Just my 2cents.....
Edward
Edward Wesson 60MGA

Steven, yes 3 main and 5 main 1800 engines can be bored out to 1868cc or even 1950cc.
Chris at Octarine Services

I checked with Doug Jackson's site from British Automotive and he no longer provides the services you seek - so I would stick with Chis at Octarine or Peter Burgess. I am very pleased with the 18v, 4 synchro conversion.
Bayard DeNoie

Following on from Colyn's & Edward's comments I thought I would mention my experience with the Ford Type 9 5-speed option.Mine cost me £50 ($75) from a scrap yard 14 years ago and has never been touched since other than installation of Hi-Gear's later short throw gear stick and a right angle speedo drive adaptor - my choice, not a servicing necessity, so expensive it need not be. The mating of the 1800 to the Type 9 has also never been an issue in the 14 years, just one new clutch release bearing and operating arm bush in that time, probably due to my engineering ineptitude rather than 'mating' issues.

What rev bands you operate the engine is surely down to choice. If you want 3000+ revs all the time just select a gear to suit. I spend a lot of time around town in 3rd and 4th to get that 3000+ response.

With a 4.3 diff this is what you get with a Type 9 5=speed box in 5th on the highway cruise:

40mph = 1880-1900rpm
50mph = 2350-2400rpm
60mph = 2820-2900rpm
70mph = 3300-3350rpm
80mph = 3750-3850rpm
90mph = 4230-4350rpm
100mph = 4700-4800rpm

Since doing those figures some 7 years ago I have fitted a 3.9 diff. As Colyn states it affects acceleration a little, but those lower gears in the Type 9 are quite long and you can hold in each much longer than the MGA box, certainly in first and second. I don't do so much motorway cruising these days so may well go back to the 4.3 at some point.

Finally, I would concur with Chris at Octarine about the ease of fitting the combination. He does it professionally, but even I was able to remove my 1500 engine and gearbox and fit the Type 9 + 1800 as a one-off in three relatively relaxed days, single handed, working it out as I went along.

Steve
Steve Gyles

More in your part of the world, and Dave has LOADS of MGA knowledge and has an 1800 in his car

http://www.classiccarclinic.com.au

Dominic Clancy

This thread was discussed between 08/03/2014 and 10/03/2014

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