RenoHuskerDu
Senior Member
I've been battling tach issues for a month. I finally found and installed a NOS tach that works, cable drive. It required a little IAO (improvise, adapt, overcome) to get installed as the clip on the back was somewhat different. But it runs.
Then it stopped. We took it out and shortened the cable a 64th, thinking it had stretched over time and was pushing on the tach too hard. That worked for a while, then I noticed revs going up on the tach but not on the motor. 3000 rpm just off idle. I pulled the dash again before that NOS tach blew up, and experimented.
It seems the angle of attack of the cable on the back of the tach has an effect. I put in spacers to adjust that.
Still it occasionally stops. So last night I ran a bunch of silicone lube down the cable. The cable seems to be too long and take bends that aren't necessary. We found an older cable going thru the firewall, which was simply cut off (!). The truck has a huge extended life air filter in the way. Now I wonder if somebody added that and used a longer cable to go around it.
Does the tach cable drive in the IP have a friction drive, or is it positive? I'm pretty sure now that when my tach stops, the cable stops spinning. It's noisy as heck too in there.
1984 Cumming 855 Big Cam in an IH S2500 dump.
Then it stopped. We took it out and shortened the cable a 64th, thinking it had stretched over time and was pushing on the tach too hard. That worked for a while, then I noticed revs going up on the tach but not on the motor. 3000 rpm just off idle. I pulled the dash again before that NOS tach blew up, and experimented.
It seems the angle of attack of the cable on the back of the tach has an effect. I put in spacers to adjust that.
Still it occasionally stops. So last night I ran a bunch of silicone lube down the cable. The cable seems to be too long and take bends that aren't necessary. We found an older cable going thru the firewall, which was simply cut off (!). The truck has a huge extended life air filter in the way. Now I wonder if somebody added that and used a longer cable to go around it.
Does the tach cable drive in the IP have a friction drive, or is it positive? I'm pretty sure now that when my tach stops, the cable stops spinning. It's noisy as heck too in there.
1984 Cumming 855 Big Cam in an IH S2500 dump.
