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MG MGA - MGB engine in an MGA?

I am now working on a 1957 1500 MGA which I haven't ever driven, as I got it in non-running condition. I have heard lots about putting MGB 1800 engines in these cars for improved performance. Doubtless the bigger engine would be more powerful, but I wonder how much the 1800 engine would add to the ease and comfort of the daily, mostly low-to-moderate speed driving that I plan. I am willing to make the switch, but I don't know if it would be worthwhile. Your opinions would be greatly appreciated. By the way, I have a 1966 MGB so I am familiar with the way its 1800 engine drives.
M.E. Whalen

M.E.

It added to my daily drive comfort and regular motorway excursions. But I did it in parallel with fitting a 5-speed box.

I can't speak for everyone, but I believe most do the dual modification to combine the extra power with better suited gearing for today's roads.

Steve
Steve Gyles

Simplest (i.e. cheapest) approach is to use a 3 bearing B engine (using the MGA backplate and starter motor) straight onto the A gearbox, especially if you're not going to 'give it some beans' as I believe you chaps say over there!
My A has run like this since 1976 (I think that's when I did the swap - old age and all that).
Regards
Andy
A S Duff

Nothing is simple I swapped to a 1800 B engine at he same time as fitting a 5 speed box and a supercharger I swapped to the B engine as I did not want to ruin the 1600 unit.

In retrospect I would say that the 1600 unit is fine but use a 5 speep box which transforms the whole driving expereiance

I ran the standard engine and gearbox for a couple of years belive me the standard 4 speed box is absolutly shocking, It spoild what is a great car. I know we should be restoring these cars as thy were ment to be but the gearbox was out of the same parts bin as the rest of the vehicals at the time designed to get saloons rolling and with atop speed of 80 Mph.

P.s. I have Kept everthing to put it back to standard but I dought it will ever be put back. Maybe if in the future if the only way to sell one is as standard then it may be put back a MG intended.


Hope this don't confuse you even more

David
David swaine

If you do decide to go with a 1800 “B” engine, then by all means go with an early “B” 3.9 “pumpkin.” A five-speed would be great as well if you can justify the expense..
David werblow

I'm in the middle of putting an 18V (5 main bearing) engine with a Sierra full synchro 5 speed in my '61 roadster. To make my install easier I had a custom alloy 3 main bearing 1800cc back plate and lightened alloy fly wheel fitted (same dimensions as 1600 MGA)this way the stock transmission cover can be fitted. Everything is bolt on so it is reversible,(if a future owner decides to bring it back to factory correct.
photos of the progress here http://picasaweb.google.com/chrisvelardi/MGARebuild#
Chris Velardi

Wow Chris that is a-lotta-hard-work!!

I have done 4 similar restorations but when you see it all presented like that, you realise just how many aspects are involved.

Well done, very comprehensive and professional.

Barry
BM Gannon

Chris,
During the year I am been seeing your photo work several times, this is remarcable not to mention all the labor that you are invested in this restoration.
Congratulations!!
R Garcia

Just to balance the arguement I like my MGA with the standard gearbox and the 1600CC engine. It drives just fine as it is not my fastest sports car. I helped it drive better with a simple gearing upgrade of the 3.9 MGB diff. This makes high mileage european touring a lot easier.

For power I use my turbo charged midget! :-)
Robert (Bob) Midget Turbo

By far the easiest conversion is a 3 main MGB into an MGA.

Arguably also the best.
Bill Spohn

My car has a 5-main MGB engine that was installed by a previous owner. When I restored it, I decided to eschew the expense of locating an original 1500 engine and rebuilt the 1800. A couple years ago, my differential disintegrated and I put in a 3.9 gearset to bring RPMs down a bit. It's a very good combination, but I wouldn't have made the mod if the PO hadn't got me most of the way there. I'm keeping the original gearbox, because that's an important part of the driver interface with the car, and I want a gar that drives like an MGA. It's just an MGA with a little extra horsepower.
David Breneman

My previous mga was a standard 1600 mkII and it drove well, I loved it and wouldnt have changed anything on it.
My present car is a 1600MkI and is fitted with a 3 bearing mgb engine which has been over bored and has a modified cylnder head with a fast road cam. It has an amazing amount of low down torque and this makes it a really easy lazy driver with gear change points becoming less important than the in the 1600 mkII.

It also has a 5 speed sierra gearbox which is really superb to use. Having synchro on 1st gear makes 1st gear a much more useable gear than it was in the old 4 speed especially on tight ascending corners and the overdriven 5th compensates well for the slightly lower ratio 4.3 diff.

The gearshift is remarkable with scarcely any movement needed on the gearlever and feels absolutely perfect for the car, like the original but better.

So on balance, whilst I loved my previous car, the new one is better, it is torquey on the twisty minor roads and perfect on the motorways also.

I would certainly recommend this set up, but whatever you decide, dont worry, its an mga, you will love it!
Cheers
Colyn
colyn firth

I will also add to what seems to be a current theme here. My 61 came with a 1500, MGA gearbox and an MGB 3.9 diff. I changed to the 1800 3 main and just love the difference it made. It transformed a OK sunday driver into a great little car with enough umph to climb hills without having to downshift to second. It accelerates quickly and handles highway speeds just fine. Because most of my trips are in town or on secondary roads I don't really need a 5 speed. That being said I may look to change that at some point in time.

Kris
Kris Sorensen

Another vote in favour of the 1800 and 5 speed combination. Mine is an early 5 main bearing engine mated to a Sierra gearbox and the standard 4.3 rear end. It's a great combination and really makes the MGA so much more enjoyable to drive.
Andy Bounsall

Here's another vote for an MGA 1600 engine with 3.9 gears in the rear end. Goes far and fine. Marvin
Marvin Stuart

I installed a 1974 MGB engine and overdrive into my MKII. Ported polished heads, mild cam, pertronix distrib, five-core radiator. Also have the 3.9 pumpkin. It is probably the best of both MGA and MGB: handling, power, fun. But there are subtle trade-offs: the B setup is more powerful and refined...perhaps never "meant" for the A experience, which by nature is more like a go-cart. But the thrill of instantly hitting 90 on the freeway, darting in and out of traffic, then tackling the twisty mountain roads at 60 in third gear overdrive...woo-hoo! I believe this setup is better than a supercharger.

I prefer the notchy "british feel" of the OD tranny to the smooth neutral feel of the Sierra 5-speed. Plus I LOVE flicking a dashboard switch to downshift instead of moving my hand to the shift lever. Old school.


Jim P

> "...the thrill of instantly hitting 90..."

That made me smile. We ARE talking 4 cylinder MGs here, right?
Andy Bounsall

Andy

He didn't actually say MPH!! However, I agree with Jim. In that configuration the MGA is lively and accelerates very quickly for a 1950s car to that sort of speed. Better that many modern medium spec cars. I put it up to 100mph last week - 4250 RPM.

Steve

Steve
Steve Gyles

When I bought my restored Mk2 Coupe early in 2008 my intention was to fit an MGB engine (probably 1840cc Oselli fast Road as fitted to my MGB) with a 5 speed gearbox However I found the original 1622 rebuilt engine performed so well that I decided only to fit the Sierra gearbox. I have been well satisfied as the performance is now fine for our roads and I can cruise happily at 70-75 mph on motorways at under 3500 revs (4.1 rear axle) I have since done 5000 delightful miles and find I use the car more than our regular driver !!
Paul
P D Camp

I guess I'll be the infidel at the gates here, and ask: If you want an MGA, why change the MGA driving experience? The MGA transmission is one of the best ever made, and with the addition of synchro in first gear (as fitted in later MGBs) is probably the finest transmission ever fitted in a light car. (The only thing that the stock MGA transmission lacks by today's standards is synchro in first gear.) It's a feakin' work of art. Why give that precision up for a pickup truck transmission? I just don't get it. Don't hate me for asking this...
David Breneman

This thread was discussed between 02/10/2009 and 07/10/2009

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