Optical difference between HPMX gen I & II?

[Alstrup]

As header.
Can annyone tell the difference by looking at them? I was never much into these carbs in the first place, so i do not remember the optical differences, if there are any.

Thanks
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https://www.thesamba.com/vw/forum/viewtopic.php?t=435993

[DeathBySnuSnu]

My first gens had the enrichment pistons and springs with the blank off plate.

The newer ones I have seen (not owned) do not have any of the enrichment circuit or block off plate at all....never cast in or machined.

I think that is where gen 2 came in.....at the die re-tool.
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[[email protected]]

Gen 1, and 2 aren’t much different. It wasn’t till the 3rd gen did they start the solid enrichment circuit with the 4 progression holes. Then the 4th gen had the idle jet vent tubes.

[bugguy1967]

Yes. Gen I and II both had plates. Gen I had some faulty screw-in pieces that could be remedied by swapping with Weber parts. Gen II fixed those issues. Gen III eliminated the enrichment circiut with a cast-in boss. I've had good luck with Gen IIIs. Gen IV has jet doctors and another progression port. I've used one set. They're just as good.
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"A petrol engine can start readily, run smoothly and give every appearance of being in good order, without necessarily being in good tune." - Colin Campbell, "The Sportscar Engine"