I'm not sure exactly which vehicle you have so I'll try to be genera yet as specific as possible to help you determine the problem. I'm assuming here its a Gas Fuel engine.
1.) if its a carburetor type engine, You may need to adjust the RPM to increase or lower the Idle. Its commonly called the Ideal screw and adjust the air fuel ratio to stabilize the engine fuel mixture to increase the RPM.. its found on the Carburetor.
2.) ts fuel injected you will need to adjust the throttle body position to archive the same effect.
if it has a distributor , you can turn the distributor as well to adjust the RPM.
rough idling is usually caused by Mounts, since you changed yours the next most likely issue is the RPM itself or idling speed / rpm. If its to low you ill have that issue.
other possible cause is the distributor points (if any).. bad plugs, bad plug wires.. but those cause other issues while driving as well.
Well I don't want to assume you know this so: new mounts will generally transmit more NVH (Noise Vibration Harshness) through the crossmember/chassis and into the cabin than sloppy old ones. New motor mounts will reduce slop and harsh knocking during transitions between on-throttle and off-throttle but most likely would also magnify any engine vibrations that were already present. Simply put, mounts don't vibrate...they transmit vibrations. To what degree is dependent on how stiff the mount material is.
Answers & Comments
I'm not sure exactly which vehicle you have so I'll try to be genera yet as specific as possible to help you determine the problem. I'm assuming here its a Gas Fuel engine.
1.) if its a carburetor type engine, You may need to adjust the RPM to increase or lower the Idle. Its commonly called the Ideal screw and adjust the air fuel ratio to stabilize the engine fuel mixture to increase the RPM.. its found on the Carburetor.
2.) ts fuel injected you will need to adjust the throttle body position to archive the same effect.
if it has a distributor , you can turn the distributor as well to adjust the RPM.
rough idling is usually caused by Mounts, since you changed yours the next most likely issue is the RPM itself or idling speed / rpm. If its to low you ill have that issue.
other possible cause is the distributor points (if any).. bad plugs, bad plug wires.. but those cause other issues while driving as well.
Well I don't want to assume you know this so: new mounts will generally transmit more NVH (Noise Vibration Harshness) through the crossmember/chassis and into the cabin than sloppy old ones. New motor mounts will reduce slop and harsh knocking during transitions between on-throttle and off-throttle but most likely would also magnify any engine vibrations that were already present. Simply put, mounts don't vibrate...they transmit vibrations. To what degree is dependent on how stiff the mount material is.