5-10% throttle strange vibration

Grayson_Oldwood

Hello all

Im experiencing this strange issue where if im coasting down a hill in any gear and i need just a touch of throttle to maintain speed. Between 5-10% throttle travel there is a subtle but noticable vibration. Ive researched the issue and all i can come up with is a "lean tip-in" where the fuel mix is going wrong when carb makes the transition from the idle circuit to the mains.

Has anyone experienced this issue or have any advice? Could this be an issue where the jetting is incorrect? Or could this be a misadjusted fuel mix screw. Could a couple more degrees of timing fix it? I think im running 12° right now.

Its a 2.2 carb fake weber and pacesetter headers. Thanks in advance for any help or ideas.

Axel-Breaker-Earl

That vibration could actually be your Center Bearing Support on the driveshaft. Slide under the truck and see if you have any play in that Support Bearing..........unless you have a short bed Auto Trans truck.......those trucks have a one piece driveshaft and therefore do not have a Center Bearing Support built into the driveshaft.