Bewy said

[1] Piss off the Holley & refit the AVS
[2] Because engine A runs on pump gas, it does not mean that engine B will too.
[3] The 455 Olds has the longest stroke of all the big blocks.
[4] What does that mean? Here is a quote from the Sig Erson cam catalog. Note: this quote is ONLY in the Mopar 440 section, no others. "...beware of too much duration.."

The short stroke of the 440 does not tolerate cam duration very well. Not surprised that it likes 25* init/idle timing & in fact it will probably idle better with 35-40*. You get this by using about 10-20* static & add the rest of the timing by using an adjustable vac adv unit [ Allen Key fully CW ] connected to a MANIFOLD vacuum source to add the remaining timing. Tee-ing into the brake booster fitting is OK for this.
Example, highest idle speed is achieved with 32* idle timing. You could use, say, 15* initial & add 17* via the VA unit. Most adj VA units have a 30* range, so you would have to fabricate a stop to limit the travel of the actuator.
Until you get the idle timing dialled in, you will never get the best performance that the engine/cam/carb are capable of...

Eye watering gas smell. The dist mods ^ need to be done BEFORE touching the carb. Hook up the PCV as the factory had it. Drill a 3/32" hole in each sec throttle blade [ NOT the pri blades ]. With timing sorted as above, get the engine idling correctly. Remove carb & check transfer slot showing below pri blades. Should be 0.040" or less, less preferred. If more than 040, enlarge the holes in 1/64" increments until the gaps is 020-040". It would be a good idea to enlarge the Idle Feed Restriction 0.002".

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HSDemon said

I ran a 440 Charger as my daily driver for years, it had a Comp Cams 230 degree duration cam @.050 and I had no issues with the Holley 750 4779 DP that I was running, ran 2 different 4 barrel Holleys with no issues and no need to drill anything. Ran a factory cast iron 6 pack intake with the factory Holleys with no need to drill anything and no issues. Ran 18 degrees of static timing and had another 18 in the distributor all in by 2200 RPM's, but this was a 9:1 engine, which the OP's is not, vacuum advance was disconnected. OP already tried to get more air in with an air bypass and nothing changed, so drilling holes on the throttle blades will not make a difference. An additional 6 degrees of cam timing is not going to make a difference. If you put a TON of initial advance, and then add another ton of vacuum advance connected to manifold vacuum on an engine with 200 PSI of cranking compression, you will have a so much detonation off idle that you will have a high probability of damaging pistons and piston rings. I have no idea why Erson would put such a statement on their website, as there are so many variables to timing depending on what specific compression you have, gearing, car weight etc... Any engine that you advance the timing on at idle will idle better. You want something to idle really good, just lock out your distributor advance and put the initial timing at 36-38 degrees, idles like a kitten purring, but it will kill your starters trying to start it on the street when the engine is hot. On my old Road Runner 10.80 bracket car we locked out the distributor advance and just ran it at 38 degrees, idled great at 1200 RPM's even with the 650 lift solid lifter cam, tunnel ram and 2 Holleys. The OP needs to be really careful tailoring how fast of an advance he using.

Also 100% disagree in getting rid of a 750 Holley on a 440 with a 236 cam at .050 and putting a 600 CFM AVS. This makes no sense, the Holley carbs are way more tolerant of big cams and modifications and are way more tunable for high HP big cam engines than an AVS, not to mention that a 600 CFM carb on a modified 440 is woefully small and will kill a ton of power.

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