Throttle shaft to baseplate sealing & clearances

[Justa1time]

Good Afternoon,

Today's topic Holley 3310-6 secondary throttle shaft sealing methods and clearance.

Holley offers two ribbon thickness for this application.
.015"
.020"

I have the .015" now and the overall clearance is .009"- Seems a bit excessive. Holes are as close as they can be to round.

Mcmaster Carr offers a teflon sealing material in .017" in a sheet that I may order & try.

Tossed around the idea of a brass sheet in .017" and make a spiral cut seal instead of straight like the factory seals.

Or ream this hole & bush then hone to fit. ( but then what to do with the machined steps in the throttle shaft from the factory?

What is the best solution? I am open to ideas and also wanting to know what everyone looks for in throttle shaft to baseplate clearances.

Thank you,

Bryan

[VMC]

(To preface: I rebuild & restore carburetors for a living)

In all honesty you're chasing a problem that doesn't exist.

Holley vacuum secondary shafts are designed to be a loose fit in the base in comparison to the primary side. As long as someone hasn't reamed out the secondary shaft bore and it isn't otherwise damaged, just make sure the secondary shaft is straight and assemble it using the .015" strips. As long as the blades are properly aligned and the shaft operates smoothly once the blade screws are tightened down, it's good to go.

[Justa1time]

Vmc,

Thank you for your input. I will keep the factory .015" seals on the secondary.

[jsgarage]

VMC, when I was fiddling with carbs (the last century), the worn throttle shaft bores seemed to be egg-shaped. So either I add external teflon o-rings held in place by a washer & a light spring, or I bushed them with copper.