I recently installed new tachs in my Fountain with twin 502 EFI,s. Both tachs read the same at idle. About 300 rpm. At wot they go just above 3000. I know Both engines are running correctly. Top speed is still mid 70's. I think the switches on the back of the tachs were set correctly but now I'm not sure. I think they had two positions, 4cyl and 6cyl. They are set for 4cyl . I thought that was correct for a v8.
Thanks for any help.

Jerry.

They should have 3 positions - 4, 6, and 8 cyl. I think you just did not see the 8 cyl position.

This should cure it for you.

Hmm... If you set it on four cyl instead of 8, one would think that it would show too many rpms...........maybe I dont understand how it works. Are they maybe set for two stroke 6 cyl .

I fixed mine last week.. there are 3 settings.
You will know if it's on the wrong setting cause it will be WAY out of whack.

I used the adjuster screw and my RPM multimeter to dial it in as close as possible down to 10rpm's..

I should have it out next weekend. I hope I can see the back of the tachs well enough to see the switches . I hope I dont have to pull the panel. The steering column is a pain and it seems I have to take it appart to get the panel out far enough to see anything.

Thanks.

I was scared as hell to pull mine.. came out no problem.. wiring was clean.. very simple.. just look behind the gauge.. very straightforward.. make sure you bring a real small flat head to turn the adjusting dial.

M