Join Date: Sep 2000
Location: Washington, Michigan USA
Cross-rams were over-the-counter dealer parts only - never installed in production. Your 750 should work fine, probably just needs a good cleaning and a rebuild kit, and the floats set properly (don't buy anything but the correct Holley kit - the parts store "generic" kits are junk). The original 4053 carb was a 780, way too big for the street, but they had to build production Z's with them so they were SCCA-legal for Trans-Am racing. Truth be told, 302's run much better on the street with a 600; better metering and booster signal due to higher venturi air velocity, better driveability and throttle response. Jeg's sells a 600 Holley #0-80145 for $260 that's physically and visually identical to the original 780 (4150, dual-feed, center-hung floats, vacuum secondaries) except it has an electric choke. Had one on my Z for a while when Jerry MacNeish was rebuilding my 4053, worked great, straight bolt-on including the stock fuel lines, jetting was fine right out of the box.
'69 Z28 Fathom Green