Vehicle:
- 1978 FJ40
- original 2f rebuilt about 3 years ago
- DUI dizzy
- Sniper EFI
- original 4-speed
- fresh u joints
Issue:
My truck has a “rumble” that’s most pronounced around 2000 rpm in 3rd gear. It vibrates a little in every gear around 2000 rpm, but it’s worst in 3rd. It subsides the minute I let off the accelerator and comes back when in step on it again. It feels like it’s the motor, but it’s hard to tell with all the other noise in the truck.
Things I’ve played around with:
- fresh u joints (one was stiff), no difference
- timing: When I retard the timing it seems to get better, but it’s way retarded right now at about 2 deg BTDC and I live at 6k feet. I disabled vacuum advance as an experiment with no noticeable difference. The motor runs just fine - silky smooth even at idle and higher RPMs without a load.
So I’m looking for thoughts from the more experienced folks. Is it normal? Any tricks to diagnosing the issue? Any smoking guns in my description of the issue?
- 1978 FJ40
- original 2f rebuilt about 3 years ago
- DUI dizzy
- Sniper EFI
- original 4-speed
- fresh u joints
Issue:
My truck has a “rumble” that’s most pronounced around 2000 rpm in 3rd gear. It vibrates a little in every gear around 2000 rpm, but it’s worst in 3rd. It subsides the minute I let off the accelerator and comes back when in step on it again. It feels like it’s the motor, but it’s hard to tell with all the other noise in the truck.
Things I’ve played around with:
- fresh u joints (one was stiff), no difference
- timing: When I retard the timing it seems to get better, but it’s way retarded right now at about 2 deg BTDC and I live at 6k feet. I disabled vacuum advance as an experiment with no noticeable difference. The motor runs just fine - silky smooth even at idle and higher RPMs without a load.
So I’m looking for thoughts from the more experienced folks. Is it normal? Any tricks to diagnosing the issue? Any smoking guns in my description of the issue?