....rivets that hold the valve to the shaft..?

The only ones I've seen have the valve welded to the shaft.

If you grind the weld smooth with a die grinder then you can tap the shaft out and clean it. Start by tapping back and forth to loosen it up. Make sure you note the position of the valve so you can weld it back right. Digital photos work great.


"It's just a phase. He'll grow out of it." Mama, 1964

1956 Chevy 1/2-ton 3100
1953 Chevy 6100 "The Yard dog"
1954 GMC Suburban Now with a new proud owner.