How to adjust secondary throttle PLATE opening?

[fussfeld]

How/where to adjust secondary throttle PLATES, not the air doors/flaps, but throttle plate openings?

This is not the carb in question, this one seems well-adjusted.  It's an original 83 1/2 ton truck carb:



The one on my engine, i'm not getting practically ANY secondary openings when the primaries are at WOT----i might be getting 1-5% opening on the secondaries, if that.   Yes, i made sure the choke is fully open and the lockout tang is out of the way.

Yes, i did read all 3 books and still not clear/maybe i've got poor reading comprehension......?

[tayto]

can you rotate them open by hand when not engaged by the lockout?

[fussfeld]

can you rotate them open by hand when not engaged by the lockout?

Yes.

[Cliff Ruggles]

You are looking at the WRONG place to adjust how far the secondary throttle plates will open. 

Those parts only need to be "adjusted" so that a small gap exists between them so the link doesn't hold the secondaries open when they close.

Look at how the mechanism operates and you will notice that when the primary shaft reaches a certain point it has a bent piece of linkage that engages with a the bottom of the piece your link is in.  You need to bend that piece toward the rear of the baseplate to move the link further resulting in the throttle plates opening further.  The baseplate will need to be removed to do this and you will need a pretty stiff pair of needle nose pliers.

I would make a positive stop for the secondaries first, then start bending a little at a time until you get full opening against your stop.  It's not complicated or finicky, just look at the players involved and you will quickly see where the parts engage and what needs to be adjusted to get the plates fully open at WOT........Cliff