IDLE AFR QUESTION

[GTO Geoff]

Cat herder,

All Holleys have/had TSRs. The TSR: also called the idle down channel. It could be a removal jet, or just a drilling in the casting. The sizing of it will depend on a few factors, one of which is the T slot itself. The T slot is shorter [ & richer ] on a performance carb versus an emissions carb.

[Right hand drive]

[rgalajda]

[CDN]

RHD TKSfor that explanation good stuff thats what I was trying to understand

Thanks guys my question was theoretical to just better understand the impact of those two on cruise simple answer was all I wanted but RHD made it more clear to me

[cat herder]

I prefer a TSR around .120", seems to give good results when IFR/IAB is right. /s

[rgalajda]

[CDN]

FWIW I have found the Holley aftermarket HP carbs have a .128 tslot supply orfice in main body with long duration cams you still need IFR arond .033-.035 so you typically restrict the t slot to about .080 to get lean cruise esp if you have a baseplatewith short slot
Small cam yes you can just reduce IFR / bleeds to get lean cruise

[cat herder]

[cat herder]

Wait, are you TSR Guys falling into the chasing-a-specific-number trap? On the wideband? You see a number you don't like and then go trying to make the number be something you like better? Or is the TSR fixing an actual driveability symptom that can't be fixed with normal IFR/IAB changes?

[GTO Geoff]

I don't have a wideband, nor have I used one.................... & I have done just fine for over 50 yrs.