sync hole on back of tach

[Stolat]

Hey everyone. I have a 93 330 sundancer with carbeurated 454's. My port side tach is off by about 100 rpm's at idle. At higher rpm's it is off by a little more. While doing some poking around I found what appears to be a hole on the back of both tachometers that read "sync". Is this hole a location where a tool can be inserted to match up both guages? If so what type of tool is used to make the adjustment. I tried getting a good visual but the spot is a little hard to get a good look. Any insight would be greatly appreciated. Thanks.

-Steve

 

[Audrey II]

I believe it's just a small flat head screw driver I did it once many years ago. You should use a dwell meter to make sure the you are adjusting them correctly. You can clip it on to the terminals right own the back of the tach. It helps to have a second person to tell you when the are set right so you don't have to kept claiming out from under the helm.

 

[Stolat]

Audrey,

What's a dwell meter?

 

[Bob J]

I believe you'll find that hole is to sync for either 4, 6 or 8 cylinder engines.

A dwell meter measures the dwell angle of the contact points in the distributor. A dwell meter is much more accurate than setting the points with feeler gauge.