Try adjusting the idle mixture screws. One at a time. Screw IN until rpm drops, then OUT until you have max rpm/smoothness. If nothing changes, then that indicates a blockage/malfunction with that side of the carb.
Every engine is different & all have a 'sweet spot'. It is quite possible to have a larger engine get better mileage than a smaller engine if the bigger engine is operating in it's most efficient range.
A trick that I have used in the past for carb heat insulation when you do not have room for a spacer or do not want to use a spacer:
- drill out the carb mounting holes to 7/16"
- use some insulation over mounting bolts/studs. Heat shrink, or some spark plug lead sheathing often works well
I have no experience with E fuel in our old cars, but I can tell you this: it has no place being in a metal carburetor.
I keep E10 in the shop for parts washing because it is cheaper.
A few years back I left some in a container overnight, very mild weather. Next morning there water drops in the...
He stated the dwell was 45*.
This could be so many thinks:
- water in fuel
- sediment blocking jets in carb
- cam lobes going flat
I am leaning towards electrical. It is also external. Check: plug wires & spark plugs [ or replace ]; inspect dist cap, rotor for carbon...
Do not delete the PCV. It keeps the engine clean internally. All carbs that use PCV are designed for the air flow they add. Make sure the PCV is not gunked up. It should rattle when you shake it. If blocked with gunk, it might let in excessive air & be contributing to the problem. Have you got...
I doubt 0.003" of wear is causing any problems. You have an adjustable air+fuel supply [ the mixture screws ] to compensate for variations. That is why it is adjustable.
I tuned my first carb in 1964 & I am still learning.....
I never use a vac gauge for idle adjustment, I tune by ear & feel...
Although it is hard to tell from the pic, I doubt that that amount of wear is causing the problem.
I have always found 4 bbl Holleys to have a lot of shaft clearance, even when new, compared to other brands, so 2 bbls probably the same.
Worn shafts [ if they are worn ] do not cause fuel to...
It is not ign.
If you can screw the idle mixture screw in until it seats & the engine does not stall or at least run very rough, then the engine is getting fuel at idle from somewhere else.
Check the PCV valve; it should rattle when you shake it. If that checks out, remove the carb & see how...
Ign coils rarely use the available secondary voltage. But the fools fall for the big numbers, such as 60kv must be better than 48kv, right, even though the spark plugs will only ever need 28kv to fire them.
Very unlikely that a coil rated with a 3kv higher sec voltage provided a 'better' spark...
Unfortunately, the term 'elec ign' covers a wide spectre of suspects. Same applies to ign coils.
There is nothing secret about ign coils. If you want the longest/best life/best spark from any coil , follow the instructions as to whether it needs a bal res.
I recently rebuilt a 455 Pontiac engine with the same problem. The top rings on 7 out of 8 cyls were broken, in pieces. The ring pieces were carboned up, obviously been running this way for a long time. Engine ran reasonably well, just had this oil problem.