Well, completed the swap of my "skimmed to the valve seats" head with a near stock unit (thanks to Alfa Parts, San Francisco for sourcing a great 1300 head and factory sodium filled exhaust valves), and a bunch of nettlesome issues simply went away! I've lost a bit of power with lower compression, but the driveability is worth the exchange.
To give you an idea of how close the tolerances were, there were places on the 1400cc wiseco pistons in the shape of each valve, where no carbon formed at all. No nicks present on the surface, but there was no room for error to be sure. Talk about tight squish areas.
The new head was chamferred for clearance of the pistons at the edges, and at the advice of my engine guru, Tom Turner in JAX, we retarded the intake slightly, and similarly advanced the exhaust... to provide a bit of further comfort with the domed, higher compression, wiseco pistons. A bit more clearance with a bit more overlap.
I'm interested in racers impressions about this technique, as I remember this effective increase in overlap as a method of motor set up for road racing. Probably not better for emissions, but possibly a means of increasing gas flow?
It's great to be driving the little Nuova Super around with a smooth idle, better gas mileage, and a more melodic exhaust note.
To give you an idea of how close the tolerances were, there were places on the 1400cc wiseco pistons in the shape of each valve, where no carbon formed at all. No nicks present on the surface, but there was no room for error to be sure. Talk about tight squish areas.
The new head was chamferred for clearance of the pistons at the edges, and at the advice of my engine guru, Tom Turner in JAX, we retarded the intake slightly, and similarly advanced the exhaust... to provide a bit of further comfort with the domed, higher compression, wiseco pistons. A bit more clearance with a bit more overlap.
I'm interested in racers impressions about this technique, as I remember this effective increase in overlap as a method of motor set up for road racing. Probably not better for emissions, but possibly a means of increasing gas flow?
It's great to be driving the little Nuova Super around with a smooth idle, better gas mileage, and a more melodic exhaust note.