[Healeys] Longbridge head modifications

[Andy Thorp]

Since it is a bit quiet, here's something I've been playing with over the (southern hemisphere) winter. I was always interested in just how "bad" the Longbridge gallery head was given that it is pretty much the same layout as the later ones with two carbs and a log manifold channeling air through a series of abrupt 90 degree bends. The biggest improvement in the later head is the bigger valves, and when these are fitted to the gallery head with chambers and ports relieved accordingly, the air flow rises to above the stock 3000 setup. The exhaust is a little different though- the 3000 exhaust valve is too big and reduces flow due to bore/block shrouding. Hoping for 125hp from an otherwise stock Longbridge engine this summer once it is all back together.

Andy.
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