Weber Question

May 4, 2008
Point Judith Area, RI
Just did valve adjustment - all are within spec...

Getting a SOLID, 21 in Hg of vacuum at idle.

Weber 38

However, truck idles fine (750RPM) at initial startup. As soon as truck reaches operating temp, idle does not go below 1000/900RPM. I am thinking that it is a choke related issue - already checked that electric choke is getting voltage - it is.

Maybe manually cycling the choke?

I'm very very happy with how she's running right now - and really happy with the vac. numbers.

Maybe I'm just stupid!
Oct 14, 2007
Sounds like it's working properly.

Set the idle after it is fully warmed up to like 750 rpm.

To use the electric choke on cold mornings, turn the ignition on to power the choke, press in the pedal a few times to set the choke, then crank it over. With choke set it'll idle at like 1500 rpm until you "release" it with the pedal (quick press) after a few minutes of warmup. I do this every morning.

It'll probably idle a little low after chock release (like 550) until it fully warms up then it'll return to the 750.

hope that helps


Mar 18, 2008
Lehi, Porter Rockwell's home town
Setting the idle speed should be done on a hot engine. Then adjust the choke to compensate for cold operation. All of this assumes that your idle mixture is correct and there are no vacuum leaks. If it gets fairly cold where you are, I highly reccomend a fluid heat riser if you don't already have one. It is virtually impossible to get a carb right to work in very cold weather as the venturi effect causes an even greater drop in temperature and the fuel drop out rate goes through the roof.
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