valve float, shimming springs? (1 Viewer)

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what happens to the motor when you pump the brakes?
 
If it's like an MGB's carb,
It's not - only adjustment screw is for idle mixture.

If your only symptom is an anomalous vacuum guage reading, then throw the guage away and just drive the truck.

12 deg BTDC is not an exotic timing setting for 7,000 ft - the OEM HAC set the timing at 13 BTDC for 4,000 ft and above. Although with 9+:1 compression you could possibly still have some knock - if you do set it back, if not leave it alone.
 
what happens to the motor when you pump the brakes?

nothin. solved that one a while back trying to "richen" the mixture too. good guess though, when i swapped boosters, i noticed smoother running.

i will have to try going over the manifold with starter fluid. i have done that in the past with no findings, but i havent done it lately.

i may back off the timing a couple of degrees and see what happens. i am still wondering about jetting though. if it runs lean at cruise, that would be most likely jets that are too small, wouldnt it? of course then i have a hard time wrapping my brain around that one because my jets are set for sea level and i am going between 4500 and 7000 feet on a regular basis and things 'should' be plenty rich at 7000 feet...
 
Eh.. pretty easy with performance mods to have it run lean with seal level jetting.

Should run better with a bit more fuel if it is lean at cruise...
 
generally speaking, it is lean under cruise. it runs lean most of the time above ~2000 RPM.

WOT, i can see it go toward rich with accel pump squirt, but as i hold, it slowly ticks back to lean.

need larger jets?
Assuming everything else (manifold, gaskets, HAC) is working correctly, then the pri. main jet needs increased.
 
sounds like another good lead. i assume i would need to disassemble the carb to find out what size jets i have to start, then i need to find a good source for larger jets.

oh great master of the venturi, jim?
 

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