I haven’t posted in quite a while. I have a d150 with a 225 from a 73 dart. I’m currently running a Holley 1945 that I rebuilt awhile back. I was having some issues with running rich, to the point of eyes burning. Took the carb apart and the nos float was falling apart. I’m guessing from today’s gas. Also the return spring for the accelerator pump was bound. I got a spring from mikes carburetor, put back together and runs great with one small problem. Then I pump the gas the accelerator pump arm moves so slowly that it takes awhile to get started since it’s not really putting any fuel into the intake. Any insight into this? The accelerator pump diaphragm was still very pliable.

I have noticed that some accelerator pump pistons (the plastic part) have poor, or no clearance to the bore.

I have long suspected that something in modern fuel swells some of them, and not others.

I have done nothing to verify this, but I have pistons that I have set aside after finding they dragged on the piston wall (or plain didn't fit) that fit just fine in the same carb body after sitting around a few years (in air, not fuel).

My initial presupposition was that they mere mismatched to the carb they were in when I had found them (ala parts store rebuild inattention to detail).

Maybe I should mic all the ones I have loose, label, soak in gas, re-mic, and report findings.

This does make sense since the old spring was bound. Maybe I’ll try a new accelerator pump diaphram. Thank you.