How to set the motor RPM

[sf38a1]

Ok I give How can you set the the motor at the 650 RPM, I have a dewll/tack meter 12v . I can hook it up to a 12v battery,to operate it but where do i hook up the the green lead that goes to the coil to get RPMs. I have used the timming light to set the timming,with a 12v battery and hooking up to #1 plug wire. that works fine but the tach got me confused

[vacca rabite]

I think that you need a 24 volt tach.

If you put a 12v tach on the negative coil terminal, you are probably going to fry it.

Zach

[sf38a1]

how would it hookup ? any Ideas ?

[Binford]

Brute4c posted this in another thread not long ago:

Originally Posted by brute4c

If you do have something that need to connect to the coil, you can take the lid off the ignitor and verify which wire is which...coil negative is the place to hook up a dwell tach for example. On the outside of the ignitor housing is a large hex plug, pretty much facing rear, that you need to remove. Run your test wire in through that opening and up to the top of the coil and then hook it to the verified correct terminal.

Hope that helps....

[sf38a1]

Yea that helps, thanks. I forgot about that plug. I have to get this motor set. thanks

[randyscycle]

An inductive tach like a Fluke meter, or similar type of multimeter would probably be your best bet here. Then there is no worry about any connections physically. It also will work regardless of the voltage.

I generally sort of do the idle adjustment by ear, as I have never been able to get much of anything carbureted to idle that low even in perfect mechanical condition.

[Barrman]

There are also digital tachometers that hook up like timing lights to a spark plug wire.

My Gasser M35 is supposed to idle at 450 rpm. I don't like the way it feels about to die all the time that low. So, I turned on all my lights and ran it down to 450, using a digital tach hooked to a spark plug wire, just to make sure it would charge. Turned it off with all the stuff still on just to fire it back up again and make sure the charging system worked that low. It did.

But, like I wrote, I don't like it that low. So, starting from so low, I gently and slowly turned it just a hair at a time until the fender I was leaning against felt smooth. Then I walked around to the exhaust and listened, got inside and listened/felt. It took me a while, but I now have it at a speed that doesn't have the truck shacking, no weird harmonics in the cab and the exhaust sounds even and smooth. Then I set the idle air mixture screws to the highest vacuum for each and went through the entire idle speed adjustment thing again by feel and sound.

I will be doing all this on my 396 in another week or so as soon as we get to the FE. I imagine my vacuum gauge will get used a lot that week.

[Binford]

Won't you need to do it yet again at 8,000 feet of Buena Vista altitude? If so, I'd wait and do it once you arrive!

[Barrman]

That is what I was writting about. BV.

[Binford]

Oh. I read that.