The Staff of Motorsport Marketing
The Staff of Motorsport Marketing Writer
2/27/20 8:17 a.m.

Story by Johan Dillen • Photography by Dirk de Jager

When the Twin Cam engine arrived in 1958, MG was finally able to deliver the power that MGA buyers had been craving for several model years. Fulfilling that promise proved difficult, however, as reliability problems cut short the caree…

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wspohn Dork
2/27/20 11:26 a.m.

Nice to see an article on my favourite car.

The factory did make a mistake by forcing Thornley to produce the model in numbers before it was properly sorted out. They never did solve the piston burning issue that plagued the engines until after production ended. Turned out to be simple - a vibration period that caused the float to jam and starve the engine. Solution - flex mount the carbs = no more problems.

Had they worked that out during production, chances are that the cars would have been very competitive with the Porsches and Alfas. There would likely have been a plus cost model of MGB with a version of the DOHC engine.  This was the only time since the 1930s that MG had cars running competitively in their displacement class, and not to put too fine a point on it, they blew it.

This is the special 1950 cc engine I created for racing - always thought that the angled Jag style cam covers gave a nicer appearance than the flat ones on the Fords and Alfas.


2/27/20 4:17 p.m.

An MGA did win it's class (and 23rd overall) at Sebring in 1957, but, it was a pushrod car, not a twin cam. 

It was driven by Canadian Ed Leavans, and  Alen Millar.  The car is alive and well, and I've been vintage racing it for the last 8 years or so at various events in Canada and the US

2/28/20 1:57 a.m.

Though I am a long time Twin Cam fan and owner ('59 RHD Roadster) the MGA's best finish at Sebring came in 1961 when the two 1600 Coupes entered came 14th and 16th OA in a 62 car field and 1st and 2nd in class. The first 13 places went to 9 Ferrari's, 3 Porsche RS61's and a Corvette. These were pushrod powered cars not Twin Cams though the engine blocks were 1622 castings under bored to 1588 and there were no water passages between the block and head so they could run without a head gasket. If you look closely at the engine bay of #43 you can see the external water passage between the rear of the block to the head. The drivers were instructed not to exceed 6800 rpm during the race. In 1962 Aaltonen's Tulip Rally car was powered by a 1622cc pushrod engine. Here are a few pics of the two team cars at Amelia Island in 2012 and some engine details. I own #43 driven by Sir John Whitmore and Peter Riley in '61.

bmw327 New Reader
2/28/20 12:10 p.m.

My grandfather owned a twincam from new and rallied it extensively. I still have the number plate from the 1961 1000 mile rally run by the MG Car Club in NY.  Dad had some 8mm movies of the car that aren't the best quality but they are digitized and well narrated.


wspohn Dork
2/29/20 12:09 p.m.
Sebring61 said:

These were pushrod powered cars not Twin Cams though the engine blocks were 1622 castings under bored to 1588 and there were no water passages between the block and head so they could run without a head gasket.

Thanks for posting that - I hadn't seen a pic of a dry decked block before. They started doing that prewar on the blown cars and apparently some poor apprentice was designated to do the final lapping in by sitting there rubbing the head against the block using a bunch of valve grinding abrasive.

3/4/20 2:48 p.m.

In February 1965 I was a 20 year-old who had been driving motorcycles since 16. I wanted a sportscar and saw a 1959 MGA for sale in London. It was a red coupe with a twin-cam engine. I bought it for 350 pounds on the "hire-purchase". It sat for a while because I failed my driving test. In the summer of 1965 I drove along with my friend's MG TF from London to the Yugoslav coast.

The MG TF preferred to cruise at around 65mph. This was very boring for me, so when a Porsche 911S Targa went by at around 100mph I decided to give chase on the Austrian autobahm. Never caught up to the 911 but travelled down the road at 100+ for several minutes. Then on a long downhill section I got the engine up to the 7000 redline, the speedometer was pegged at the 120mph limit.

I new this was not good, so pulled over to check the oil. I carried oil in a gallon can because it used oil at an alarming rate. I put at least 3 quarts in.

The car had 40k when I bought it and I drove it for another 20k in the nearly 2 years I owned it. I was young and it took all my money to keep it going. But as my first car it has great memories.

3/12/20 7:57 a.m.

I've been vintage racing my twin cam for nearly 20 years. The only catastrophic engine failure was about 15 years ago when an over stressed original  bottom end fastener failed and a connecting rod put a whole in the side of the block. 
In my opinion the twin cam version of the MGA is equivalent to the ZR1 upgrade of the basic Corvette. 
Today the basic push rod MGA's have been upgraded with MGB brakes, transmissions and engines so the advantage has disappeared. 

Many push rod MGA racers build highly stressed super high compression engines without reserve as replacement parts are available at a reasonable cost. Not so for the twin cam whose many parts are unavailable at any price. 

Safety Fast!

jenny_piu New Spammer
3/13/20 3:06 a.m.

What a cool post, and the first picture is awesome!

4/29/20 1:11 p.m.

Nice article on the Twin Cam. Do note that the 1500 B-series engine wasn't new for the MGA, MG first introduced the 1500 in 1953 for the ZA Magnette, which was in production in 1954, and was off and doing rally duty before the MGA was introduced in 1955. The original MGA used other parts from the Z as well, such as the transmission and drum brakes. ZB Production got the slightly upgraded 1500, and ran from 1956-1958. 

2/3/22 2:52 p.m.

My Twin-cam experience started wanting an MG with more power than my 1958 MGA. BMC in Berkely, CA. had a 1960 (old taillights, so it was probably a 1959 model) in Red with a Black interior. I liked the car, but the car did not my style of driving.  It seems I was always fouling the sparkplugs. I eventully changed to a different heat range on the plugs. The engine did rev, and was fun to drive. After having a problem with the cam chains, I gave up and decided the Twin-cam was not for me. I traded it in of a 1962 MG Miget.  

rdstr New Reader
9/23/22 8:15 p.m.

Owned a cammer coupe (YM31545) one of ~260 in late 60's. I'm told car is now back in the UK

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