Reversing Holley "reverse-idle", and...

[Walking-Tall]

The idle feed restrictions are probably hiding, vertically, in the idle (outer) wells, about 1/4" below the brass cup plugs up top... a bit below the upper angle ~0.120" holes...

Silver stickers (or remnants of) around the mixture screws, indicating "reverse-idle"?...

Primary idle air bleeds for regular idle will be in the neighborhood of 0.070"... "reverse-idle", smaller. Have I seen Holley assemble and sell a mish-mash of the two, regular and reverse parts together, and fixed 'em? Yes.

Are you able to gauge what size the primary idle air bleeds (outer) are?

Are the mixture screw tips short and stubby ("reverse-idle"), or long sharp-tipped (regular idle)? How big are the small holes (~0.102" ("reverse-idle") or 0.063" (regular idle)) in the metering block that the mixture screw tips go into?...

Sometimes if the engine is wild enough or the idle circuit is too rich or very touchy to adjust, some will drill those "auxiliary air bleed" holes to lean the idle circuit some and to make the mixture screws less sensitive...

I'd suggest to block the "auxiliary air bleed" holes. Your combination obviously doesn't need them at 1-3/4 turns out with the mixture screws...

If the original or a replacement rating power valve is in there, I'd suggest that you take that silly 2.5"Hg power valve out, throw it away, and put at least a 6.5"Hg power valve into it. The brown vacuum secondary spring is a bit stiff (slow, maybe not fully opening) too. Purple one works good in most cases.

If you're up for it, I'd also suggest removing the idle well cup plugs...

Procedure for ^ : http://carb-rebuilds-plus.boards.net...-plugs-holders

... drilling out those probable hidden idle feed restrictions, and installing 0.026" (stock/mild camshaft?) primary idle feed restrictions, submerged in the down-low position...

Honestly, (and for increased "fun" (or terror, LOL!) for your water-skiers, lol) Windsor would really like a 750 on it

[Walking-Tall]

Additionally...

Where are the holes that are drilled out into the primary throttle bores, through the #9/#18 or the #8/#17 passages?...



...........

[CC1991]

Hey Mike, thanks heaps for the info - much appreciated! Ok, so the primary idle air bleeds are definitely not 0.070", they're closer to 0.050". No indication of a sticker around the idle screws, but the screws themselves look like every other picture of holley idle screws I can see online, and the hole they go into is definitely smaller than 0.102". I'll need to pull the carb and take it to work, I've got pin gauges there I can use to get proper measurements of this stuff.

Broadly speaking though, it does appear that the main body may have been set up for reverse idle, but the metering block is normal.

The "auxiliary" air bleed holes are present in both sets of holes (#9, 18, 8, 17), but they're at different heights. From memory, I think it's the 8 and 17 ports (to transfer slot) that are drilled straight across from the metering block face of the main body, whilst the 9 and 18 passages are drilled from the primary bore side into the curb idle passage, right near the bottom of the body before it meet the throttle plate, pretty much bang on where you showed them getting plugged in your first post on this thread.

The engine is nothing fancy, as far as I'm aware it's exactly as it left the Correct Craft factory with whatever cam PCM put in their marine engines. I do think however that the carb has been messed with at some point in its life. The list number does seem to match up with a marine application, but I don't know why it has those aux air bleeds drilled in.

It does have a 6.5 power valve, and always has as long as I've owned it. The factory specs for that list does say 2.5 power valve, but I agree that seems awfully low for a marine engine that spends its life under moderate to heavy load.

I'll pull the carb again soon and try getting some proper measurements and plug up the aux bleeds, see how it responds! I'll also try to find those hidden IFRs - didn't know they can also be found in the vertical well, I thought they were visible at either top or bottom of the well!

Thanks for sharing your knowledge and experience!

[Walking-Tall]

Quite welcome. How'd you make out?