Re: Effects of PVC Vacuum And Idle Speed
Yes you should run the PCV valve but with or without it unless you have a very big cam you should be able to get that thing to idle down. What carb are you running? What is your timing set at? Go back to the basic's of carb tuning, start with making sure you have at least 10 degrees of initial timing. Then close your sec throttle blades all the way and just take some tension off the screw so the blades don't bind. Set your Idle mixture screws to about 1 turn out. Now use the idle adjustment screw to close the pri throttle down or up with the engine running. You did say your floats are adjusted properly didn't you?
That should work if you have a Holley or maybe a Q-jet but if you have a Barry Grant it won't work... Mind you all this is doing is getting your idle back on the idle circuit of the carb. You may have other performance problems to tune out later. If you can't dial in your idle this way you may have an internal vacuum leak or some other issue. Once you have it idled down check your timing. At 1000 rpm you may have been on the timing curve, if so adjust the timing bac up to where it was. Idle should go up but this time just close the pri throttle blades a bit to bring the idle back down.
Let's assume this works and your idle is at 800 rpm. Try to lean out the idle mixture a touch Shoot for highest vacuum reading or best idle. Turn in one idle mixture screw just until the engine falters and then back it out until it's steady. Do the same with the other then adjust the idle if needed. Now shut off the engine and make both mixture screws the same. Most holleys I have tuned on a small block seem to like 3/4 turn but what ever you set your at split teh diff to ge them the same. Example is 1 is at 1 full turn and the other is 1/2 turn. make them both 3/4 turn...
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