Ok i have Holly's hp 500 carbs, i believe. Does some body know where on the carb metering block where the idle holes are? maybe a pic. I need to shut them down a little so i can get the air bleeds or mixture srcews to work. i'm tad rich at idle. A little lean up top.

When rich en up the carbs by 20 a cross the board. I lose my idle and goes too fat for for the idle srcews to work. They idle great at the standard hp jetting, and run strong, just lean on cly 1,7,2,8,
I was told by making a v shape out of like 30 thousands wire and put in the holes it will shut down the flow some what.

Ok holly gods let me have it!!!!!!!!!!!!

If you idle mixture screws have no effect you need to do three things.

1 Turn the idel mixture screws all the way in then back them back out 1.5 turns each.

2. turn the idle speed screw down so the primary throttle plates are less open and the engine won't idle.

3. Then go to the secondary throttle plates and open find the screw that limits the closing of the secondary throttle plates. You need adjust this screw so the secondary throttle plates are open at rest enough to idle.

Once you have this condition, the idle mix screws should be responsive and you should be able to kill engine by turning them full in. If you can, then begin normal adjustment.

I would also consider the power valves in your troubleshooting.

BT

Agreed. The secondary idle stop screw is located on the under side of the throttle plate, carb must be off to set. If this adjustment is not right it is very hard to make engine idle properly. This adjustment allows the engine air to idle without pulling all thru the primarys and pulling fuel with it, also helps with transfer from idle to part throttle. Thus the name transfer slot. Normal setting would be to make the transfer slot appear to be square. Hope this helps. Info on this is avaliable in the Merc shop manuals.