Hello David,
I won't be able to help you with the proportioning valve but it should have nothing to do with air in the lines. The first thing I need to ask is did you bleed the master cylinder? If this is not done or not correctly you will have to bleed the brakes several times to get the air out. The lines also should not be an issue for air, are you determining it's air because they brake pedal gets hard after pumping it?
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69 393W Sportsroof deluxe
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