I set my Holley 94 three half turns both sides and still have heavy carbon build-up on plugs! Timing? hotter plug? Cooler plug?
Photos very necessary !!! Normally carboned up spark plugs need...smaller hole in the jets ! Plus, three and a half turns out on the mixture screws...sounds a bit excessive. Mike
Carb air mixture screws generally 1/2 to 3/4 of a turn out from a gentle bottom out in carb. Try running carb or carbs with no air filter to try and “lean” out the “fat” mixture —-start with a fresh set of plugs that are suggested for the engine you are running. Make sure spark plug wires are transferring full voltage—-check float level in carb or carbs for proper setting—-too high of a float level can contribute to a richer than normal mixture—-improper mixture can also result in too high fuel pressure. If you have a Flathead??—2 lbs of pressure is usually adequate. Overhead valve v8 generally require closer to 5-6 pounds fuel pressure. Flatheads Forever!!!
That's 1.5 turns, right? I saw that it had been read a 3.5 turns rather than three one-half turns. In any case, I really doubt that idle mixture is your issue, unless your engines spends most of its time idling. I'd look at the power valve first then jet sizes. Edit: I forgot the idle transfer circuit. If you have that much fuel setting now, how is the idle speed? It may be so high that the tranfer hole is opened dumping way to much fuel in. First thing I'd try is slow the idle down as much as possible, then lean out the settings. Then set the idle speed and revisit the needles. That should ***ure the the transfer hole is covered by the throttle blades at idle. Or look for a vacuum leak that is the cause of needing so much fuel.
Idle screws, full turn or 1 flat? 1 flat=½ turn. Timing needs to be 4-6 at idle, our gas is better than the old days so a degree or 2 extra is ok, but late is no good. Power valves are the wild card on 94s. There's a couple types, both fit, 1 is wrong. I'm not there yet but when I have a solid footing I plan to share. Seat them gently, go 2 flats to start, adjust them out til it speeds up, or in til it speeds up. They WILL NOT be the same. I've done 1 or 2 vintage engines where both sides were equal, and interestingly I find the p***enger side on most V8s and V12s takes a ¼ turn more. Manifolds are not 100% equal in mixture delivery. Clean the plugs again, and shoot for a color that's like coffee with cream under load and idle testing. Let us know too please, and yeah, pics help.
I might be wrong, but isn't the 94's float bowl referenced to the air horn (via a tube press-fitted into the air horn casting) rather than externally vented? This means that an air filter blockage does not effect mixture quality (same as a B-model Stromberg). A blocked air filter then robs power but does not change mixture quality. Amals and SUs on the other hand are externally vented, and the air filter makes a difference to the mixture quality. Cheers, Harv
Put about 10-12deg of initial as base, Start with one full turn on idle mix,start with 800-1,000 rpms & install a good $180 ish wbo2, use as a tool ,make it so easy , & you will see ,point where your @ & what adjustment needed ,, strap or weld on . A + ,~ & plug harness to O2 & drill a hole .. You can remove or hide, O2 average readings 9-13 Rich 13.5-14.5 good ish 15-20 Lean
Do a search on Holley 94 "economizer valve" (we just call it a power valve). If that thing is completely shot you can look down the carb at idle or barely off idle and see fuel drizzle out of the booster. If it isn't a vac gauge will tell you what you have at idle and while driving under light load. More cam can equal less vacuum, sometimes dual exhaust can even lower idle vacuum some but usually drops it at least a little faster in normal driving. Maybe an inch or 2, or a bit more. If it's weak (let's say it's a 6.5) and your cruise vac is like 8 it may drizz a bit even if not full open. Old PVs get sloppy exposed the ethanol gas and get all wonky. Daytona Carb (in FL, go figure) has good stuff and fast friendly service, been using them for a long time. Good luck. I really suspect this is your issue.
all you are going to change with the screws is idle mixture. Do you drive it or just let it idle? I know nothing about your engine so take what I am going to say here with a grain of salt. More often than not "carbon" buildup is not carbon at all. loose guides or worn cylinders can cause what most think is a carb problem. If it is a carb problem and is sooting up I am going to suggest that you either have your floats set too high, your chock is not coming open, clogged/restrictive air cleaners, or you need to rejet. Any or all of those will cause one to run fat.
If thats a True 28deg of initial, Do you have to get engine spinning with starter especially when @ run temp then flip power to ignition coil or Remove ground to Mag?
When the vacuum hits it goes up. A 46ish 59A has a crab with an adjustable vacuum gig on the side. Like a GM setting, you initially set at 4-6 then hook up vacuum. We may be onto something here. If the timing is set low running then it will be late, or retarded when vacuum actually drops under load. Worth a double check.
On the FordBarn, Jim Linder talked about timing and initial setting for stock, very mild, FH Ford V8. Might be worth doing some searches there, I don’t want to put something out that he didn’t say, but I was stunned about what he said.
That's idling at about 800rpm with the vacuum fully kicked in. So: static + RPM driven + vacuum. Frank
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