Jet-A-Vator carb grid.

[Isaac Zackary]

Originally Posted by freebeard

My Superbeetle needed a 34PICT and I couldn't [at the time] find the one I had laying around. My VW shop ordered the 32PICT and adapter instead. They said it was a more tunable/maintainable/known. ¯\_(ツ)_/¯

If I understand correctly, the 32-1 and -2's were more popular because they were less complex because emissions were less strict. The "-[number[" represents the amount of complexity made to the carb for emissions reasons. Also back then people were throwing "009" mechanical/RPM advance universal distributors on their VW's that worked well with an over-rich carb, but not a lean one. The 34-3's and -4's were designed to run leaner and were known to not work well with the 009 mechanical advance replacement distributors unless they were jetted richer. But going for richer and less advance is not best for fuel mileage for obvious reasons.

[Isaac Zackary]

Well I'm giving up the Jet-A-Vator for the moment. It just seems to take too much power from driving the car. I need to climb up 2,000ft then drop down 4,000ft then come back along that same route twice a week and the restriction seems a bit much.

The car isn't quite yet road worthy but the smaller idle jet did make an improvement in the AFR. Went from about 10:1 to 13:1 (7,700ft high altitude effect). I still need to go smaller, both on the idle and the main jet. The carb has two other jets I might mess with, an air correction jet and an auxiliary jet, as well as three high speed power orifices, two of which can easily be canceled out as need be.

I'll keep an eye out for a used dual throat carb. I just have my doubts about them since the carb I have has so many more fuel circuits that can be tinkered with to get more exact AFR's across the board. And I don't know if the main venturi will actually be smaller than the tiny carb I already have.

A couple of other mods I haven't mentioned here yet. The engine CR has been upped from 7.3:1 to 9.5:1. The cam has been reground to a specific custom cam profile for fuel mileage that is also designed to run a 9.5:1 CR without pinging. I also machined the heads to create a quench or squish area around the edges that will help speed up combustion and increase "mechanical octane". The piston tops, combustion chambers and exhaust ports also have ceramic heat reflecting coatings. And the sparkplugs are a protruding type that put the spark just a tad closer to the center of the combustion chamber.

[Isaac Zackary]

So far I'm getting 34.9mpg on average with both city and highway driving mixed.

However I got my 55mpg diesel running again so I'm driving that now.