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MG MGB Technical - New pistons-which to buy?


Hello everyone,
I'm in the process of rebuilding the engine for my '72 MGB. I have everything at the machine shop and need to order parts soon. The shop said order 30 over pistons since they bored the cylinders. Can anyone recommend where to buy the new pistons and what brand to look for? I also need to get new cam bearings while the engine is still at the machine shop.

I'm also going to look into a Peter Burgess head for the car. Everything else should be fine with the engine. The shop also magnafluxed the crank. Any other recommendations?

Thanks in advance.
Dave
David Plantz

The shop bored the cylinders before they had the pistons at hand? This is something that you do after you have the pistons at the shop. They must each be measured so that each piston's clearance to the bore is correct. County brand pistons are good quality and reasonably priced. RAY
rjm RAY

David. As Ray notes, the pistons must be in hand before the cylinders are bored and honed to final size if one is to have a good fit. Both County and AE pistons for the MGB are made in India. One wonders how many manufacturing plants are making pistons for old, obsolete British engines? I suspect, but cannot confirm, that both brands are made in the same plant, on the same machines, and put into differently branded boxes.

On the cam bearings, Dura Bond and Federal Mogel both make precision fit bearings that do not require special reamers to be used after installation.

Les
Les Bengtson

I bought County pistons for my MGA. Each pison was identical to the others to .0002", when measured at the same respective points. So they are very consistent, but the shop should have had them in hand before boring and should have asked you for them. Ask them why they didn't. Maybe they have a good honing allowance.
Art Pearse

Hi dave,

Dont know if you can get them in the US but I have Mahle pistons in my engine recomended by the builder.

The other usual brands are Hepolite and JP which are high end and the others already mentioned.

Regards
A J Ogilvie

My experience of Hepolite has been disappointing, the boxed sets were never anywhere near in balance. JP tend to be a little heavy as do the Mahle ones. The County ones have always weighed within a couple of grammes per boxed set and if I buy say 5 sets I can balance the sets by mixing and matching to 1 gramme. At times Hepolite sold graded pistons....meaning they made a mistake on the ODs!!!!!! The ODs are spot on with little to no variation. I have had an occasional problem on inspection but less than I had with Hepolite when I used them. Any problems were sorted rather than being fobbed off....for instance no oil drilling in gudgeon pin hole in piston....dont need it says Hepolite!

We measure before we have the boring and honing done but this has always proven we could just bore to the usual size and have perfect clearances with the County pistons.

No I do not get paid by County and will happily moan about things if they are not correct.

Peter
P Burgess


Hi Guys,

I should have been more clear in my original post. The shop is waiting on me to order the pistons but they believe the cylinders will clean up at 30 over.

I read through some previous posts on here about compression ratios but am still a bit unsure of what would be best to do as far raising it. I would like an engine with good power but want something that will hold up as well.

Thanks again for all of the great advice.

Dave
David Plantz

Use the low compression pistons for regular gas or 87 octane, use premium or 93 octane for high cmpression pistons. Both will have the same engine life. Why go to Burgess, when there are great head shops here?
I have been working with a world class porting shop in New York, on a customers TD, & other cars.
Len Fanelli

Hi len

I tend to prefer being referred to as 'Peter Burgess' rather than 'Burgess' seems a tad friendlier to me, that is the way we run the business too :)

Peter
P Burgess

Sorry Peter. Len, with a L :)
Len Fanelli

Hi Len with an L, sorry about that I always seem to get lower case when I thought I had held the shift key with this latest 'pre-owned' laptop I am using!
I also seem to be getting more dyslexic with my typing!

Peter
P Burgess

David-
With a Peter Burgess Fast Road head you will have his combustion chamber modifications. The Unleaded fuel here in the USA is volatle stuff, but with his cylinder head you can safely go to a geometric compression ratio of 9.6:1.
Stephen Strange

This thread was discussed between 06/10/2010 and 10/10/2010

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