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MG MGA - 1600 High Compression Pistons +20

Anyone know where I can get a reasonably prices set of 1600 high compression pistons from in +20 oversize ?

Moss now only sell low compression at a very reasonable 120 per set but alas won't source high compression pistons.

Preferably in UK.

Thanks in advance

Mark Hester

I have used Jahn's pistons in
Anaheim California. They made a set for my 1938 VA tourer. They had very fair prices.


Buy some standard 1622 MGA pistons and have your rods reamed slightly to take the wrist pins. But that will actually give you about 0.030" over size. And they are flat top, so good compression. You should be able to find some standards as they aren't usually in great demand.
Bill Spohn

I bought a set of 40 oversize flat top 1622 pistons and rings from NOS (new Old Stock Locators) through their eBay site about 18 months ago. (I believe they may be the same company as Scarborough Faire).
They proved to be both excellent, and very reasonably priced.
T Aczel

Try asking Chriis Betson
dominic clancy

Good advice Bill. If I had known, I would have got the block bored
From standard to +30 rather than the +20 I now have.

I can't believe we can't buy these Pistons readily.

I emailed Mahle Pistons who now own Hepolite but they can only supply low compression.
The standard Pistons were high compression.

I tend to avoid flat tops, as the squish patern is poor for our cylinder heads, they are ok if you have a small dish machined back into them though but this all costs.

Anyone know a manufacturer that is still making them?

Australian JP Pistons lists several part numbers for the 1600 engine but not the compression ratio.

Mark Hester

Hi Mark,

I would suggest getting forged pistons from Venolia in California. I get a set for my 1622 MGA and also for my 3 bearing engine in my Magnette. They do them with 2 compression rings and 1 oil ring, made to order and abt 250-300 a set. They are good to deal with and good quality pistons. I'd avoid the County 5 ring pistons, which are pretty much the only cast pistons available in the UK now. The pistons from Adelaide don't get a very good wrap either.

I'll text you the contact details. They take about 2 weeks to make them and if you get them shipped to Australia there is no duty or GST/VAT. it was actually Bill Spohn who sold me on them.

Rgds David.
David JM

Thanks David.
Very impressive web site for Venolia:

I purchased Arias pistons for my 1924cc twin cam engine.

I'm looking for a cheap off the shelf option, as this is only a temporary engine which has lost it's engine number tag.

I've asked:


B&G list loads of pistons but alas you can't determine their compression ratio via their web site.

Your right, no need for 5 ring pistons with modern ring technology.


Mark Hester

I wonder if all the MGA MK 2 owners are aware that they've been going through life with an 'inferior squish pattern'? Must keep them up at nights worrying!

(I don't think it matters, is what I am saying, Mark) ;-)

You may find that reboring to the 1622 size is cheaper than sourcing new pistons from another source. I would NEVER have a bock bored unless I could hand the machinist the pistons that were going to be used in the block.
Bill Spohn

I wonder if all the MGA MK 2 owners are aware that they've been going through life with an 'inferior squish pattern'? Must keep them up at nights worrying!

(I don't think it matters).

Thanks Bill for saying exactly what I'd been thinking too.
Getting decent compression (with flat top "poor squish pattern" pistons) certainly brought my previously sluggish MGA engine to life.
I just couldn't figure out, after years of MGB ownership, why my MGA felt so insipid. I even ran the car on a rolling road dyno (54 miserable HP, and that's AFTER re calibrating the distributor). Finally after swapping out my (standard for the Australian market 1622 Mk II cars) low compression dish topped pistons for flat top ("poor squish") pistons, my car, finally, literally "lit up". It now spins out, and just GOES, just like these cars should. It even SOUNDS much crisper. It still won't match the torque an additional 200cc (12%) an 1800 engine can provide. But I'm now, finally, very content. The car has become fun to drive.
T Aczel

Having a 1622 supercharged engine with flat top pistons I can only agree with Mr Aczel!

dominic clancy

This thread was discussed between 30/10/2014 and 05/11/2014

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