The Stovebolt Site Forums The Shop Area Engine Shop distributor one tooth off - does it matter?

I've probably at least got some attention from the subject block with this one.....hmmmm....of course it matters as one tooth counts for quite a few degrees in error.


Suppose I was told I may have installed my distributor "one tooth off"....Is there any reason why I couldn't just loosen the collar near the base, and rotate the unit to compensate for the error. After all, we're close enough so that the vehicle runs. All I need to do is turn it until it runs the best, right? (then use a ligh for fine tuning, of course). that's a whole lot easier than pulling the distributor and "guessing" which way to re-install it on the helical gear - much less guess how much to rotate the oil pump receptor tang so that things will fit together. This is for a 235 engine. Arguments or comments ?

dublenaught,

You are right...as long as you have plenty of room to rotate the distributor, the tooth fairy doesn't give a hoot!

The problem is that external things sometimes complicate matters. If you twist it too much, the vacuum advance might be a bear to connect, or you might have plug wires that ends up stretched to the max. Other than these concerns, ' one tooth off' is only relative to where the distributor comfortably fits.

If push comes to shove on the rotation limits of the distributor, you can pull the plug wires and parade them in the direction needed, and presto, your one tooth off has vaporized.

Pulling the distributor, flopping a tooth and reinstalling it is VERY straightforward..no black magic involved, so don't freak yourself out. Good luck!

Stuart

Don't forget that you always have the option of moving the wires around one stop either way.

If it's the 6-cylinder distributor you're working with, the vacuum advance doesn't even comer into play- - - -just loosen the clamp around the distributor housing and put the dizzy anywhere it needs to be. The advance will stay right where it belongs unless you try to move it by unbolting the advance me4chanism from the block.

Just be sure when the points-open part of the cam lines up, that the distributor rotor is under the proper plug wire terminal. I think there might be a situation possible where the spark has to jump either forward or back some distance to hit the right plug wire. That will cause a miss, or a crossfire to the wrong wire as the speed increases and the centrifugal advance operates.
Jerry

yes, the advance doesn't move if I slacken the collar; and yes, I agree that it may become impractical to rotate the dist too far one way or the other. Interesting about swithching the plug wires. I had never thought of this approach. As for lining up the cam when the points break, how do I tell anything about the cam since I cannot see it?

It's called "static timing", done with the engine stopped, and the flywheel ball aligned with the pointer. Either put the truck in high gear, and carefully roll it forward until the ball and pointer comes together, or try turning the engine with the fan if the belt is tight enough. Be sure you're on the compression stroke of #1 cylinder, by either having only the #1 plug installed, or watching the valve action. Once you're sure you're on the #1 compression stroke and the ball/pointer aligns, remove the cap so you can see the points, turn the distributor housing clockwise until they close, and turn back counterclockwise until they just barely open. A test light attached from the coil (-) terminal to ground helps find the exact break point. With the ignition turned on, the light will go out with the points closed, and come on the instant the points break.

With the engine static timed, it will start, and be within a couple of degrees of the final timing point. While you've got the cap off, compare the rotor position to the corresponding plug wire terminal in the cap, and install the #1 wire to the cap tower nearest the rotor tip.
Jerry

Edit: By "cam" I mean the distributor cam, the thing that makes the points open & close. Nearly 50 years of tinkering with these things makes me think everybody jumps to the same conclusions I do when describing a procedure! Sorry!
Jerry

dublenaught,

Are you positive the marks on your timing gears line up? I would check that first, then position the distributor where it should be. You can be off a tooth on your timing gears and still be able to hit your mark with a timing light, but the engine will run like crap once you go off idle.