Post by steelypan on Mar 17, 2023 13:36:24 GMT -6
Taking a shot in the dark here, not sure if this forum is still very active or not.
BLUF: I have a 1986 I'm working on. What could possibly cause wear/damage to the grooves on the intake camshaft that engage the tachometer drive gear? Loss of timing, engine spinning backwards? Everything else under the valve cover looks pretty good. I'll try to post a picture of what I'm talking about.
Long Form: I'm doing some restoration work on a 1986 LTD. Purchased with the understanding that the tachometer wasn't working, among many other things. I figured it'd be a simple seized cable or at worst an electrical issue inside the gauge. Tested the cable and gauge with a drill, everything working.
At that point it's oh dear, must be an issue with the mechanical system in the valve cover that spins the cable itself. I have discovered that there are grooves on the intake camshaft that engage a drive gear for the tachometer, which then spins the cable going to the gauge. These grooves on my cam are pretty badly worn and won't engage this drive gear. I'm considering swapping the cams and replacing this drive gear, as I'd like a functioning tachometer and I'm concerned about friction between these parts if left in current state.
Before I do that, I want to be sure that this same issue won't happen again. I'm trying to brainstorm what could have caused this. I think it's a fair assumption that the little drive gear somehow seized and misaligned, but why? Could loss of timing or manually spinning the engine the wrong way cause something like this?
If there's a systemic issue with my cams I'll be rather disappointed, although I'm leaning towards the belief that this was somehow a freak occurrence. I'll try to attach a picture of the issue I'm seeing. Any input would be nice, I've always enjoyed shop talk.
BLUF: I have a 1986 I'm working on. What could possibly cause wear/damage to the grooves on the intake camshaft that engage the tachometer drive gear? Loss of timing, engine spinning backwards? Everything else under the valve cover looks pretty good. I'll try to post a picture of what I'm talking about.
Long Form: I'm doing some restoration work on a 1986 LTD. Purchased with the understanding that the tachometer wasn't working, among many other things. I figured it'd be a simple seized cable or at worst an electrical issue inside the gauge. Tested the cable and gauge with a drill, everything working.
At that point it's oh dear, must be an issue with the mechanical system in the valve cover that spins the cable itself. I have discovered that there are grooves on the intake camshaft that engage a drive gear for the tachometer, which then spins the cable going to the gauge. These grooves on my cam are pretty badly worn and won't engage this drive gear. I'm considering swapping the cams and replacing this drive gear, as I'd like a functioning tachometer and I'm concerned about friction between these parts if left in current state.
Before I do that, I want to be sure that this same issue won't happen again. I'm trying to brainstorm what could have caused this. I think it's a fair assumption that the little drive gear somehow seized and misaligned, but why? Could loss of timing or manually spinning the engine the wrong way cause something like this?
If there's a systemic issue with my cams I'll be rather disappointed, although I'm leaning towards the belief that this was somehow a freak occurrence. I'll try to attach a picture of the issue I'm seeing. Any input would be nice, I've always enjoyed shop talk.