Hello Ivor--------The most obvious difference / benefit is just how much lighter the Aluminium barrel is.....ie}-- much less weight to lug around and better economy...............Your engine will warm up quicker (and therefore cool down quicker ).......Make sure you get a "quality assured" one such as our hosts offer.............I bought a "Cheapie" one some time back which had a casting inclusion in the pushrod tunnel..This showed itself as a nast black, oily weep through the fins, but only when up to running temp................We inserted an Aluminium top-hat type of sleeve which cured it completely....No cost for me but Mr. Average Owner would have to reach into his purse to pay for that sort of thing...so not really a cheapie in the end..........
If you decide to get an Ally one then you'll be going back to Standard bore I assume and will want a matching piston to that size.....Remember to gap those rings accordingly as well-------TIM, what's the ring gap for an Alloy barrel ??..............and don't forget that the liner protrusion "lip" might be different than the old barrell so do a clearance check for that new Head gasket you'll also be fitting .............Finally, I'd recommend that you fit a steel insert in place of the plain threaded hole found between the two pushrod tunnels as the Aluminium can be quite soft compared to the cast iron previously used and there's a real chance you'll strip the thread, so now's the time to do it........
