21-11-2018, 02:19 PM
I have fitted late Ruby high comp cylinder heads to several 'unknown' Austin 7 engines and in most cases the results were far from satisfactory, ie rough running, loss of power. The reason has always been that the 14mm plugs of the late head oil up, causing the engine to run on three cylinders.
The late head is very prone to plug oiling, so unless you have an engine with good bores and piston rings, I would stick with the early head. These are much more kind on an old unrebuilt engine and an engine running on four cylinders will always be better than one running on three. Also kinder to the crankshaft if the engine is an unknown quantity.
If you have a nice rebuilt engine fit a later high comp head or a Ricardo aluminium head. Best bet is to get your engine running sweetly on its low comp head and assess its overall condition.
The late head is very prone to plug oiling, so unless you have an engine with good bores and piston rings, I would stick with the early head. These are much more kind on an old unrebuilt engine and an engine running on four cylinders will always be better than one running on three. Also kinder to the crankshaft if the engine is an unknown quantity.
If you have a nice rebuilt engine fit a later high comp head or a Ricardo aluminium head. Best bet is to get your engine running sweetly on its low comp head and assess its overall condition.