[Koenraad]

... My solution is to use a 1600, which will fit under the hood without too much tweaking, but bore and stroke it out to 1779cc. I am using a 1750 head as well. At the same time, I have installed 1 mm oversize valves in the head,...

Is the 1750 head not the same as the 1600 head (intake valves are both 41 mm)?

Maybe it's too late but the LDS-trick could be a nice option, "install" 10 mm spark plugs in stead of 14 mm, this would make it possible to install bigger valves.

If bigger valves are really a bonus for a fast street car is an other discussion (at a certain moment Alfa Romeo reduced the inlet valve size of their 1600-engine for better drivability).

 

[Koenraad]

... The better flow thing might just be an "old wives' tale", but I figure the chambers might be shaped better for matching up to my 80 mm bore.

I checked Jim K. famous book... just before the inlet valves both heads can be enlarged to 37 (between valve and valve seat) and 39 mm (1) (valve seat). Just before the valve guide a 1600 head can or should (2) be enlarged to 34 mm, the 1750 head to 36 mm.

Jim K. advises to enlarge the intake manifold to 37 mm for the 1600 head and 40 mm for the 1750 head.

On the exhaust side, there are no differences.

(1): For a 2000 head this dimension is (only) 39,5 mm.
(2): The numbers indicated by Jim K. can be read in two ways: as in "should" (for ideal performance) or as in "this is the maximum possible", that's not clear to me.

 

[Koenraad]

Thanks, Koenraad for the port dimensions. I was not aware of this book and will be interested to see how my port dimensions compare. Interesting that the dimensions are different for the 1600 and 1750, but I wonder whether that is due to casting differences or just an adjustment for larger displacement?

It was Domenico Chirico, a long time Alfa engineer, who said in his book that the 1750 engine uses the same head as the 1600, so casting wise, I think they are the same.

The combustion chamber will probably have a trimmed edge to adapt the bigger bore.