Weber guys

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Apr 3, 2007
Newport, NC
I recently picked up a 1975 FJ40 that the previous owner had put on a Weber 34/34. It idles real low. With the help of some other guys help here I have done this so far.
Replaced distributor cap, plugs, plug wires, rotor and condensor
Aligned dizzy properly by pulling and setting up initial timing
So anyway it starts right up but idles way too low, I have to turn in the idle screw all the way in to get about 520. If it is only about a turn or so from the bottom it idles at like 200. When I give it some hand throttle it seems pretty smooth, no backfire, just a nice accel. Another weird thing is I can turn in the mixture screw all the way in and this is where I have my highest rpm's. My question is this low idle caused by vacuum leaks? I have shot carb cleaner around the base of the carb and engine never picked up rpm so looks like no leak there. Are maybe the jets too large? Any insight in what to look for is greatly appreciated.
Forgot to mention the low idle condition existed prior to changing dist cap, plugs, wires, points, rotor and condensor.
You need to get a vacuum reading @ idle to aid in the diagnostic procedure.....
grant5127, where should I take the vacuum reading and what should I expect? Also, the weber was new when he put it on and he never really used it after that.
Cool site brian, I can get a vacuum gauge from work, out of town right now. To measure do I just remove the vacuum port hose that goes to the distributor and measure there?
take it at the fitting(should be the vac line to the brake booster) in the intake manifold right below the carb.

To measure do I just remove the vacuum port hose that goes to the distributor and measure there?

that is just the vac advance/retard, not enough vacuum there. and it's probably ported, so there is no vac there at idle anyway.

you want the vac fitting that goes to the brake booster, or at very least the pvc fitting.
Weber guys

Just go to
You should be able to find the help you need.
When setting the idle mixture be careful and follow the instructions to the letter. This is the best Weber information you will find.

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