Cylinderheads

Cylinder Head

There is a very interesting and thorough discussion by Steve Cecchele at the turbo124 forum.

Ulix offers a snippet from Al Consentino.

Combustion chambers

Here are a few of the combustion chambers that Fiat tried over the years. It's not even close to complete, it's just what I happen to have photos and measurements of right now, so if you have more to contribute, please do. Some suggestions about how each one could be reworked would be nice... and pictures of reworked chambers even nicer...

US-spec 1300

Casting: 128AC0C000040/4 4315419 Width across combustion chamber (not counting cylinder recess): 78mm

This one came from a US-spec '74, and has the circular recess that lowered the compression of the US-spec 1300 for emissions reasons. The combustion chamber doesn't extend all the way to edge of the cylinder bore so the valves are significantly shrouded.

US-spec FI 1500

Casting: 138AE2A00 4430881 Width across combustion chamber (not counting cylinder recess): 86mm

This is a ten-bolt 1500 fuel-injected head. The exhaust valve is larger and the combustion chamber extends the full width of the cylinder bore so the valves are much less shrouded.

Late Euro-spec 1300

Casting: Width across combustion chamber: 86mm

From Steve Cecchele, this is a European 1300 head from 1978. It has the full-width combustion chamber and not much valve shrouding. Without the deep cylinder recess, it offers appreciably higher compression (9.2, as against the 8.5 of the US 1300).

Euro-spec 1100 (?)

Casting: 128A 4343497 Width across combustion chamber: 78mm

This head is occasionally sold in North America as a "Euro 1300", but comparison with the previous one suggests that it is more likely an 1100 head. Although it lacks the cylinder recess of the early US head, it has the same narrow combustion chamber and consequently the same valve shrouding problems.