Knebel
Senior Member
Hey,
I need some guidance on what could cause my 360 to shake pretty decent at idle. Its the same in gear or park and sort of new ish. The engine always had a little shake but not like that.
Two things, I am running efi and have tried to adjust the idle to the most stable solid vacuum and such but the motor has a pretty strong consistent shake. It does not appear like its dropping a cylinder or misfires, I can tell because the efi works like a saw tooth pattern at idle. I have the AFR set to 13.8:1 (leaner and it gets unstable). The timing is commanded at 18° at idle and I do have the option for "idle stability spark which I have currently turned off.
So if I set it to 13.5 afr at idle, the efi fluctuates between 13 and 14.2 to keep it there. At 13.8 the fluctuation is less. However, when it goes lean it starts stumbling for a sec and then goes back commands richer to 13 and stumbles again, its subtl but noticeable. This does not happen as the efi keeps the values closer together at 13.8.
Vacuum relatively stable. Around 7 in Gear and 9 to 10 in Park. Fluctuates maybe 0.5. I dont think this is the cause as thats always been around those numbers.
The motor mounts are rubber and are bouncing the engine quite decently... I have a feeling that I always had the wrong balancer on it maybe or something I was told that the previous owner installed a "cam" but I dont know the values and the engine runs otherwise pretty good and strong. I had some issues with adjusting the crank and it would kick back on the starter and looseened the flexplate bolts, i have tightened them back up but i need a little higher stall anyway... oh I run a CDI box too!
Anyway, what should I investigate, it feels like when you screw the idle way down and it just shakes along evenly. Or like when you lean out the carb idle screws and just leave it shaking. I normally have the idle set at 800rpm. 850 makes little difference. Same with 750 (makes the shake worse i think).
I'm a little clueless..
I need some guidance on what could cause my 360 to shake pretty decent at idle. Its the same in gear or park and sort of new ish. The engine always had a little shake but not like that.
Two things, I am running efi and have tried to adjust the idle to the most stable solid vacuum and such but the motor has a pretty strong consistent shake. It does not appear like its dropping a cylinder or misfires, I can tell because the efi works like a saw tooth pattern at idle. I have the AFR set to 13.8:1 (leaner and it gets unstable). The timing is commanded at 18° at idle and I do have the option for "idle stability spark which I have currently turned off.
So if I set it to 13.5 afr at idle, the efi fluctuates between 13 and 14.2 to keep it there. At 13.8 the fluctuation is less. However, when it goes lean it starts stumbling for a sec and then goes back commands richer to 13 and stumbles again, its subtl but noticeable. This does not happen as the efi keeps the values closer together at 13.8.
Vacuum relatively stable. Around 7 in Gear and 9 to 10 in Park. Fluctuates maybe 0.5. I dont think this is the cause as thats always been around those numbers.
The motor mounts are rubber and are bouncing the engine quite decently... I have a feeling that I always had the wrong balancer on it maybe or something I was told that the previous owner installed a "cam" but I dont know the values and the engine runs otherwise pretty good and strong. I had some issues with adjusting the crank and it would kick back on the starter and looseened the flexplate bolts, i have tightened them back up but i need a little higher stall anyway... oh I run a CDI box too!
Anyway, what should I investigate, it feels like when you screw the idle way down and it just shakes along evenly. Or like when you lean out the carb idle screws and just leave it shaking. I normally have the idle set at 800rpm. 850 makes little difference. Same with 750 (makes the shake worse i think).
I'm a little clueless..