Adjusting Volvo Tachometer Reading

[Sunspot Baby]

I recently installed Balmar alternators and regulators on my two Volvo B2003 engines. I noticed I had to run at higher indicated RPM to get the same speed through the water.

Pat (Never Monday on this forum) checked RPM with a strobe and verified that tachometer indicated RPM is about 500 higher than actual.

I have searched threads but cannot find information on adjusting tachs and neither forum or tech data with Balmars addresses the issue.

Anyone know if they can be adjusted without changing pulley size?

George

[GordMay]

What make & model tachometer?

[Sunspot Baby]

They are Volvo branded tachs. One is 1994 vintage (OEM) with mechanical hour meter, the second vintage 2002 with digital hour meter. Both exhibit the same issue.

Sorry, I don't know who actually manufactures the tach, I doubt it is Volvo. I am not at the boat right now and will have to pull the instrument panels and look at the back to get model number.

Since they have the same symptom, I thought there might be a common cure.

George

[Paul L]

They are VDO tachs. The newer one can probably be adjusted via the directions here:
VDO Installation and Troubleshooting Guides - egauges.com
The older one I think has an analog adjustment on the back, but not sure.

Paul L

[Sunspot Baby]

Thanks. I'll pull the tachs and take a look at the back.
George