High idle after warmup

Got my KZ-Gal back together after a valve/shim job and carb rebuild.

Sync process went well getting all 4 dialed in around 23, and she runs through low/mid range & high power bands wonderfully. (actually pulls better then she ever has)

She starts better then ever and plugs look a wonderful white/tan. I have new vacuum caps on her and new carb holders

When cold her idle is perfect. Once up to operating temps idle climbs to 2000 with idle screw backed off all the way. The throttle pulley is all the way against return stop. Idle/air is 1 3/4 out from slight seat.

Any and all suggestions appreciated for this fast idle.

Thanks

Hi Summerheat,
Here are two possibilities that come to mind:
-1) Air leak... at carb Holders, at Vacuum Caps, in Vacuum line to Petcock...
-2) One or more carb slides was set just a little too high during carb sync, is OK during Choke operation but is open just a little too much when hot.

Best of success.
Bill

What kind of carbs? My smoothbores will not idle below about 1800 with the Kerker and jetting set up I have...Russ

vm26's / Kerker meg with 2.0 baffle & pods / 120 mains and rest of carb internals stock.

Had normal idle before work and new parts. Looks like I will be testing for air leaks and getting my Morgan Carbtune back out.

With that set up, almost guaranteed new jets will be required... Assuming you haven't already done so....

OMR, I edited as I forgot to mention main jet change.... Are you thinking something else needed?

More info... been thinking ( yeap it's dangerous)

I bench synced these carbs with the wire method. Now if I did not have idle screw turned in any during this process would it cause my inability to lower idol? Or would my manometer sync take care of this.

or stated another way

Should I have had idol screw in enough to open carbs before closing down to wire thickness?

IMHO, that's exactly the type of question that should be asked at this point... good stuff!

Remember, the nano/gauge sync only gets the slides properly adjusted with respect to each other... right. Then each one is sucking in by the same amount.

Again IMHO, in other words, it prevents any one carb (and therefore its corresponding cylinder) from not pulling enough or pulling too much. This in turn puts less stress/imbalance on any one section of the crank shaft preventing harmful harmonics (stresses) being built up.

That's what makes a really well Sync’d engine feel soooooo smooth.

Best of success.
Bill