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craigdskilling
08-31-2010, 06:51 PM
How do you now if your rpm gauge is set to the proper calibration.And if not how can you do this.
Tidbart
09-01-2010, 07:17 AM
Depending on the ignition type... Standard ignition, take an external tach and then compare to your gauge. MPI, hook up a scan tool and then compare.

Check the back of the tach and make sure the switch is set to the correct cylinder setting.

B
craigdskilling
09-01-2010, 07:40 PM
I am running a msd.Is that what you mean.I have the original gauges from my85,18 classic.I don't recall seeing that but i will take a look.
mrfixxall
09-01-2010, 08:44 PM
I am running a msd.Is that what you mean.I have the original gauges from my85,18 classic.I don't recall seeing that but i will take a look.

look at the back of the tach,their should be a plug in it,remove it and look inside the hole,their should be a 4,6,8, cylinder setting..running msd you need to remove the tach wire off the coil and install it on the side of the msd box,theirs a blade terminal on the side of it and the wire goes their.
craigdskilling
09-02-2010, 09:12 AM
The 4, 6, 8, meaning engine size.I can do that test with the ears on to see the tack move right.But to get the true rpm it will have to be under load correct.
Tidbart
09-02-2010, 11:55 AM
The 4, 6, 8, meaning engine size.I can do that test with the ears on to see the tack move right.But to get the true rpm it will have to be under load correct.

4,6,8 is the number of cylinders. The same tach can be used on different size motors. Depending on the type of gauge, there will be some kind of switch on the back of the tach. Most likely it is correct. I really don't see someone changing it. Why would they?

Yes, you can do the test on the hose. Just don't go too high on the rpms while on the hose. If you want higher rpms, put it in the water. Rpms are not related to being under load for what you are doing.

So, make sure the gauge is hooked up correctly, as fixx said, on the MSD box. Check the gauge switch on the back, set for 8. Hook up an external tach and compare the readings.
craigdskilling
09-02-2010, 03:06 PM
THanks guys will let you now in a few days.