Holley Carb Question...
Thread Starter
Burning Brakes
Joined: Aug 2005
Posts: 1,164
Likes: 1
From: Europe, France
Holley Carb Question...
I've got a Holley 600 CFM Double Pumper #0-4776.
When I adjust the idle speed screw 1 turn and a half from having the primary plates seated in the bores, the transfer slots are just exposed 0,020" under the plates. This make them look like a "square". It is just what is said in most manuals and forums, so I assume it to be correct.
Things are a little different on the secondary side :
If a adjust the secondary idle screw ( under the carb ) about 1 turn in from having the secondary plates seated in the bores ( Holley recommandation for initial adjustement of secondary butterflys ), the transfer slots on the secondaries are still far away over the plates. In that position, the secondary transfer slots are absolutely invisible from under the carb. It would need 3 or 4 more screw turns just to see them.
I would like to know if it is normal or not and how to correct it if necessary...
When I adjust the idle speed screw 1 turn and a half from having the primary plates seated in the bores, the transfer slots are just exposed 0,020" under the plates. This make them look like a "square". It is just what is said in most manuals and forums, so I assume it to be correct.
Things are a little different on the secondary side :
If a adjust the secondary idle screw ( under the carb ) about 1 turn in from having the secondary plates seated in the bores ( Holley recommandation for initial adjustement of secondary butterflys ), the transfer slots on the secondaries are still far away over the plates. In that position, the secondary transfer slots are absolutely invisible from under the carb. It would need 3 or 4 more screw turns just to see them.
I would like to know if it is normal or not and how to correct it if necessary...
Tech Contributor
Joined: Aug 1999
Posts: 14,376
Likes: 6,375
From: At my Bar drinking and wrenching in Lafayette Colorado
That's correct. On a Holley, the secondary transfer slots are higher in the bores than the primary slots, so they cannot be set to .020". A good initial starting point to use is to set the primary side to .020" and then look up through the bottom of the carb with the carb held up against a light: Adjust the secondary side so that you get the same "light gap" around the throttle blades as the primary side. This way, you will obtain equal airflow at idle through all 4 corners of the carb. On most mild engines, this initial setting will give you an idle speed that is just a tad high - adjust primary and secondary idle speeds equally from this point to obtain the desired idle speed.
