MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGA - How big can you go ??

Hi,

I have a 1961 MGA with a 16GA block. Can it be safely bored out to accept MGB pistons ? The standard MGB pistons are 3.160 ". The original MGA pistons were 2.916.

Thanks,

D
DA MacFarlane

In a word, YES
Iain MacKintosh

be careful I think they changed the liners for 1622 blocks. I have seen this info somewhere before if you search the BBS archive you might find something.
If you go too big aside from the risk of going through, the engine runs hot too.
Better to insert 4 sleeves if you want 1800 plus.

Better to keep your existing engine number and toy with another block.
Cheers <MARK>
Mark Hester

The 1588 engine was derived from the earlier 1500 engine, but was recored to allow for the enlarged bore of the 1588.

The 1622 block was a further development that had the bore centres offset and cylinders 1&2, 3&4 siamesed. This provided for a far stiffer block and was perhaps the best of the 3 bearing B series engines. Development of this block (again with a recore) gave the early 1800 blocks.


If you increase the bore of a 1588 engine to take 1800 pistons, you will be removing 0.12" (about 1/8")from the thickness of the cylinder wall.

While Iain says it can be done, I think that perhaps you should carry out a bit more research before you go this route. It could be that you need to use liners, and that will add to the cost.

You are looking at enlarging the bore by a similar amount to that carried out for a 1800 to 2000 conversion, and I gather that these are not always successful without using a liner.

Perhaps some one else can expand on this.

Cheers
ian F

Ian Fraser

Hi,

In light of some of the concerns expressed in this thread, I am going with new liners and then have the cylinders bored out to standard MGA size pistons.

Thanks for your advice,

Duncan

DA MacFarlane

If you have a 16GA, the stock bore size was 2.968 and not 2.916. What size is your current bore? There are alternatives between the stock bore and the MGB bore size that may not require new liners. You can get 1600 pistons up to .060 over ie 3.028. You could also use 1622 pistons either 3.040 (.040 over) or 3.060 (.060 over)

Jeff Schultz

I looked into using 1622 pistons when I did a rebuild on my MGA 1600.

1622 pistons were cheaper than +60 1588 pistons but the gudgeon is bigger than that in the 1588 engine, and the gudgeon pin bores would have required bushing. Bushing was more expensive than the difference in piston price.

Sadly 1622 crank and rods are not directly interchangeable with 1588 parts.

Cheers
Ian F

Ian Fraser

This is a 1600cc block not a 1500 in which case it can be bored to take 3.160 pistons. 1500 blocks cannot be bored to this size
Iain MacKintosh

This thread was discussed between 27/02/2006 and 05/03/2006

MG MGA index

This thread is from the archive. The Live MG MGA BBS is active now.