tachometer

[cls]

Can someone help with this.I just tuned up this 74 mercruiser plugs points cap,roter new blaster coil and plug wires.It now starts and runs great. the problem is now my tachometer duz not work.The resistor wire from the distutor was replaced with ballast resister with variable resistance 0.75-1.50 could this be the problem thank you

 

[Don S]

Re: tachometer

Moving this to the Mercruiser forum, it's not a Volvo.

The tach hooks to the negative terminal of the coil, the resistor is on the positive terminal. Check your wiring to make sure it's hooked up correctly.

 

[cls]

Re: tachometer

Moving this to the Mercruiser forum, it's not a Volvo.

The tach hooks to the negative terminal of the coil, the resistor is on the positive terminal. Check your wiring to make sure it's hooked up correctly.

Thanks for responding Don. Yes i know it duz. The original wire from the distrutor I believe was a resister type in very bad condition and i cant buy one
So I wired a ballast resistor between the negative side of the coil and distbutor.All other wires a in the orginal stock location the tac worked before Iam missing somthing thanks again

 

[Maclin]

Re: tachometer

The resistor should be inline with the power to the POSITIVE terminal on the coil, replacing the resistor wire that was inline. The wiring should be a straight shot from the key switch Ignition terminal thru the ballast resistor then to the positive terminal on the coil.

I know you already have a ballast resitor to wire in, but I am pretty sure you can buy the resistor wire still from a Mercruiser shop, and older 1960's or so Ford automotive ignitions used it. You could also replace the coil for one with internal resistance and just run straight wire from switch to coil. A good parts store should be able to find a universal 12v coil with internal resistance compatible with your stuff.

 

[Don S]

Re: tachometer

So I wired a ballast resistor between the negative side of the coil and distbutor.

There is your problem. You put the ballast resistor in the wrong place. Assuming the wire from the coil to the distributor is the one that was bad, that is not the resistor wire. Between the coil and the distributor is just regular wire.
What 74 Mercruiser engine do you have? They made more than one type engine and ignition system.

 

[cls]

Re: tachometer

Thanks guy's Don your right took the ballast resister off tachometer work's .thanks again :facepalm: