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MG MGA - Drilling out engine block water holes

Cooling is probably the last topic anyone will want to pick up again.... but before I reinstall my head I wanted to ask if anyone has had experience with drilling out the water holes at the back of the block? Here is a link to the page on the topic from Barney's site, .

I am running a stock engine and head. Like many others I have had cooling issues in the past, but some of the problem was likely related to the cam sprocket out of alignment by two to three teeth. I have since replaced the sprockets, tensioner and timing chain.

Any thoughts, yey or ney would be appreciated.

jjb Backman

I wouldn't advise too much tinkering with size of the water holes unless you have a real good idea what you're doing. Comparing holes in block and head with holes in the head gasket, some locations are blank and some holes are smaller than others. This is an intentional arrangement by the factory to maintain as well as possible near equal temperature around the combustion chambers for all cylinders. If you start changing hole sizes or locations you could end up with hot and cool spots, one or two fouled spark plugs at the same time as a burned exhaust valve in a different cylinder. It is for similar reason that the thermostat should have the appropriate temperature rating (for a street car with near stock engine).
Barney Gaylord

This thread was discussed on 14/01/2011

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