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Thank you Sir. As this is my first turbo, I still have lots to learn, and I appreciate your input.

This forum is such a wealth of information. Thanks to all those who went before me. Much appreciated.

My next question... there have been many references to drilling small holes in the throttle blades to help with air flow at low/idle speeds. But I've not yet found "where" these holes might be drilled... closer to the progression holes? Top, or bottom of the throttle blade? Can someone give me a hint? Or does it even matter, as long as you do it somewhere?

I'm not familiar with the DCOE, but back when I raced V8s with Holley carbs it would be necessary with low vacuum at idle.
Basically the butterflys would have to be opened far enough at idle that the transfer slots would be exposed and dump fuel before idle to cruise transfer.
Drilling the holes would allow the butterfly to still cover the transfer slots at idle.

Size of the holes determined experimentally a little at a time until the butterflys were where they should be to cover the transition slots.
Placement wasnt crucial.

Do you have bigger idle jets handy ? In the past I have drilled the jet out by hand with some number drills.

It's the lean idle you're trying to fix right ?

You can also have 2 different size idles in the if you want.

Thanks guys, but im finding im fat all over. I have some smaller mains, but im still waiting on smaller idles. It spits black soot out the exhaust at "idle", but is still rich (11.5 - 12) on the idle circuit at above idle speeds but below 2k rpm. I think it goes lean at idle, because the fuel is falling out of suspension at idle.

It's getting happier. I'm down to 135 mains (in both barrels) and the mixture screws are 1/2 turn from fully seated, so far my boost levels are minimal for tuning purposes, but the engine is starting to wake up.

Thanks again guys

Ah , I thought you said it was lean at idle.

panel wrote: ↑Sat Sep 20, 2025 12:36 pm Ah , I thought you said it was lean at idle.

It was APPEARING lean at idle, just watching the afr, but I am believing that the fuel is dropping out and causing it to show up as lean on the afr

I've given more thought to drilling holes in the butterflies. The local hardware store had some 1/16" drill bits. 0.0625" by old math... maybe larger than an ideal starting point, but is there any advantages to drilling 1 butterfly a little larger than 2 of them ideal or a little large? Is it close enough i should just drill them both?

Again, not a DCOE guy but I did look it up.

Before you go drilling holes, at idle how does your throttle plate (butterfly) position compare to this:

If drilling holes doesn't work do you have a back-up plan to fill the holes back up ?

Alexander_Monday wrote: ↑Sun Sep 21, 2025 11:39 am Again, not a DCOE guy but I did look it up.

Before you go drilling holes, at idle how does your throttle plate (butterfly) position compare to this:

I understand that my throttle plates should NOT expose my progression ports at idle. I'll know that for sure, once I remove the carburetor. I'm still trying to keep it close to the 1/2 turn after contact with the arm... we'll see once the carb comes off.

Thank you Sir

panel wrote: ↑Sun Sep 21, 2025 11:58 am If drilling holes doesn't work do you have a back-up plan to fill the holes back up ?

Well, I'm not a welder, but I believe I could solder them closed again. Baring that, I could have new replacements standing by... they're available, right?

Start smaller, work your way up.
Some carbs have air bypass screws... if present try that first.

Assuming you have vacuum balance test ports at least, don't underestimate a small fixed vacuum leak to each hole.

You can probably buy a set of metric drills in small sizes for a few bucks.
I mostly buy cobalts these days but if you only use them on brass HSS should last ~forever.