How does cam timing affect vacuum?
How does cam timing affect vacuum?
Re: Cam advance or retard for vacuum Advancing the cam will generally increase vacuum, since it causes the intake valve to close sooner as the compression stroke begins rather than the beginning of the compression stroke reverting into the intake.
Does advancing a cam increase vacuum?
Generally speaking, advancing the cam, through closing the intake valve sooner, should increase engine vacuum (and low rpm torque at the expense of high rpm torque.)
How can I increase my engine vacuum?
Hold engine speed steady at 2,500 rpm for 15 seconds, then rapidly release the throttle. Vacuum should momentarily increase a couple of inches.
How does idle speed work on a Camaro?
Idle speed screw is 1-2 turns in from when it touches the stop. Air fuel mixture screws are 1-1/4 turn out from seated. Transfer slot has the proper ~0.020 little square exposed. So timing looks pretty good (as good as I can get it), but I still have a huge rpm drop from 1,000rpm in park to 600rpm in gear.
What makes the RPM drop at low idle?
Check the timing both in and out of gear. If the timing is falling way back in gear, that’s most of your problem. Usual culprit is a centrifugal and/or vacuum advance kicking in at idle. As soon as you throw it in gear it drops back, making the RPM drop worse than it would ordinarily be. Also check for vacuum leaks.
Why does my car idle when in gear?
Replaced the carb no vacuum leaks, it idles fine it park, put it in gear and it seems like it wants to die, sometimes it does sometimes it doesnt. My car has an automatic transmission. Hi there. It is common for an engine idle to decrease when in gear, as the application of the flywheel and transmission creates an additional drag on the motor.
When do you notice your car idling low?
When you notice your car idling low, suspect three common sources of trouble: Faulty or clogged idle air control valve
What’s the best idle timing for a camshaft?
Try running about 21 or 22 degrees of initial timing. It will help with two things. It will stabilize your idle AFR by giving the fuel more time to burn and raise your idle rpms by 100 – 200 rpm.
Why does idle RPM drop from Park to in gear?
A large drop from Unloaded to In-gear idle setting can otherwise usually be attributed to either a vacuum leak or a convertor that’s to ‘tight’ for the engine set-up I agree with John. I also believe the initial 22° timing is too much, more like 12°. Tune carb with a vacuum gauge at a lower curb idle.
What should the idle RPM be on a Camaro?
Tune carb with a vacuum gauge at a lower curb idle. Stock cam should give about 18 inches at unloaded idle and a drop of about 150-200 rpm loaded. I agree with John. I also believe the initial 22° timing is too much, more like 12°. Tune carb with a vacuum gauge at a lower curb idle.
What should the ignition timing be at idle?
Increase the ignition timing at idle to 25°-30° BTDC. If your camshaft is really that big, it will like the high initial timing. If you push it out to the 25°-30° range, disconnect the vacuum advance and test drive. Vacuum advance will typically advance 14°-15° if still stock.
