Re: [T3] Carb Problems

[Steven Ayres <comwest@att.net>]

<x-flowed>StevenC=> Fuel would just pour our of the main tube

It would take an awful lot of fuel pressure to open a properly 
functioning float valve. There's been a lot of trouble in recent years 
with new valves, which are frequently put in as a matter of course when 
it's not really necessary. Did you try putting in some old OEM valves?

=>  I'm sure one of the manuals said 3PSI was correct.

The Haynes manual (the only carb manual left in print) is an outlier on 
this at 3.5psi, and the carb-version Bentley does not specify, oddly 
enough. Elfrink (p. 85) says 4.5psi, and VW's Without Guesswork ('71 
version, p. 37) says 5. The most nuanced book I have is the Australian 
Scientific Publications manual (No. 47, '71), which lists 4.3 for 1500s 
and 5 for 1600s. Elfrink specs the late spring length at 33.5mm, and 
asserts that these pumps are marked VW2 on the upper case. In the real 
world, I tested 3psi on my car and found it inadequate for long pulls, 
where 5psi works.

=> Maybe the carbs themselves are leaking through the shafts or between 
the manifold?

Shaft wear and subsequent leakage is a common problem. A good test is to 
spray WD-40 or carb cleaner on the shaft ends while the engine is 
idling. If you hear any change, you've got a leak. The remedy is to 
rebush the butterflies, which is a simple and relatively cheap machinist 
job. Manifold leaks happen (more often with dual-port heads), but it's 
relatively easy to get this right when you're putting it all together.

=> a procedure I downloaded from a list member's site

That's probably the best one.

Steven Ayres, Prescott AZ
'66 KG1600

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