89 mid cabin tachometer flutter

[mrrudely]

So a couple of months ago I changed the port engine distributor to a HEI from AAA marine.
All went well runs perfectly.
Did the same to the starboard engine last week.
Engine runs perfectly.
Problem is that the port engine tachometer now has a flutter when the starboard engine is running. (both engines running)
Starboard tach is fine, shut down starboard engine, port tach is fine.
Both engines had two wires to the positive of the old coils, port engine has a third wire.
Third wire connected or not no difference.

Anyone?

[prowlersfish]

Do you have a synchronizer? If so disconnect it and see what happens

[mrrudely]

no synchronizer

[prowlersfish]

I have been thinking about this and have not come up with anything. I keep thinking synchronizer. And you don't have one. I Had a lot of issues with the Flashing light ones crossing over. The only other thing I can think of that could be shared electrically is the batteries Make sure the switches are not on all.

I am assuming the engines are holding steady even though the tach(s) are not?

[mrrudely]

prowlersfish

thanks for giving this some thought
the engines hold steady and there are no battery switches
I was at the boat yesterday and verified my original observations at the dock
however when we went out past the breakwater we found both tachometers were fluctuating erratictally

I am thinking of installing tachometer filters which seem to be common on HEI installations

[BobCT]

Mike,

For what it's worth, I installed the exact same distributors and on my 454's and the tachs worked fine. Off topic, I put together a new spare parts "kit" (Ignition module, etc.) for these distributors but sold the engines. $75 shipped and it's yours.

I also have a full set of Int'l gauges if you or anyone else is looking (but I don't think your tachs are bad).


Bob

[prowlersfish]

prowlersfish

thanks for giving this some thought
the engines hold steady and there are no battery switches
I was at the boat yesterday and verified my original observations at the dock
however when we went out past the breakwater we found both tachometers were fluctuating erratictally

I am thinking of installing tachometer filters which seem to be common on HEI installations

Sounds like a good idea let us know.