I'm still tuning my Holley 6210-3 and wondering: should any of the secondary idle transfer slot be showing, or should it be totally blocked at idle? Last time I had the carb off, I left a little square showing. Now, it's idling a little fast, and won't respond to turning the idle screw CCW any farther. A friend said it's because of the secondary slot being cracked.
Everything else is good.

Thanks a lot! :D

I believe you have a spread-bore double pumper with a secondary fuel block that has no adjustments (versus a 4 corner idle). I have always run those with the secondary blades almost closed. Having them open too much will cause the symptoms you just described. Those secondary bores are huge, so it doesn't take much of an opening to introduce massive amounts of airflow past the throttle blades.

(In the case of a square bore 4 corner idle, you'd have the transfer slots just slightly exposed so that they look like tiny 'squares'.)

I believe you have a spread-bore double pumper with a secondary fuel block that has no adjustments (versus a 4 corner idle).

Exactly. So I should leave just a hair of the slot exposed, or is it OK to close it off altogether?

Thanks, Matt! :thumbsup:

The way I was taught for NON-4 corner idle Holleys is to seat the secondary throttle blades in their bores by backing out the set screw stop, and then, bringing the screw to zero clearance, and adding 18th turn past fully seated. The transfer slots would then be set correctly.

Opening the secondaries to make the idle quality better is a crutch, and not the way it should be done. that doesn't get the real problem of the primaries being disadvantaged fixed right.

Regards,

Milton

Opening the secondaries to make the idle quality better is a crutch, and not the way it should be done. that doesn't get the real problem of the primaries being disadvantaged fixed right.
Regards,
Milton

My idle quality is fine, just a little high. When we rebuilt the carb recently, in my ignorance, I assumed that the secondary transfer slot should be square, same as the primary slot. So, I adjusted it. My friend said that's why it's idling a little fast, that the secondary slot shouldn't be open that much, hence my question. Should the (secondary) slot be showing at all?

I've been EFI'ing my engines lately, but I seem to remember the secondary slot is not as far open when the blades are correct, than the fronts end up open. I think only .020 or so, as compared to the front wanting to be .040.

I also was taught that th4e secondary idle transfer slots really don't do anything for idle quality at all, they are there as the "off idle" fuel delivery for the secondaries and don't contribute to the idle process. With the secondary slots, they are there ti get the secondaries going from closed, before the main jet circuit stats, much like the primaries do, but without the added fuel screws and idle bypass holes under the throttle blades.

Having the secondary blades in the right place works just like the primaries do, and will cause problems, same as the primaries can, when they aren't correctly addressed.

I didn't explain that very well, don't really know how to make it easier to understand. Hope it helps, though.

Regards,

Milton

Thanks, Milton. I appreciate your time. :beers: I guess I'll keep fiddling with it until I get it right; it's pretty close now after a LOT of fiddling. :D

They are really quite simple, until they get "fixed" for problems they never really have.

Hang in there, you'll get it dialed, just use good old common sense, think about what you want to do, and it'll come around for you.

Regards,

Milton

Thanks. :D:thumbsup: