Thread: Position of H.E.I. cap in relation to firewall

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Here is a bit of weird information.---My distributor gear has 13 teeth on it. That means that if you are out one tooth on the mesh with the cam gear, then the distibutor shaft will be 360/13=27.7 degrees out of positon, rotationally. There are 8 terminal lugs on a V8, so there is a terminal lug every360/8=45 degees. So----if you are out of mesh by 1 gear tooth then your cap will be out of position by 27.7/45=0.61, or about 1/2 the distance between 2 terminals. So----it seems to me that you could be out of mesh by one tooth and still be able to adjust the distributor body enough to make the engine run.---this gets into pretty strange science, and I am sure that the engine would run, but not well, and you would never be able to line up the timing marks on the harmonic balancer with the timing pointer. I beleive that is what happened to me. I finally pulled the distributor and re-timed it with number one piston on top dead center (as well as I was able to establish)., and now the engine runs o.k. and the timing mark on the harmonic balancer does line up with the position where it should based on a 305 pointer, not the 350 pointer which I was sold (I was told they were all the same).

dont forget that the distributor turns 1/2 crank speed so
10 deg of crank rotation is 5 deg of distributor rotation!

I have the same issue. Was wondering if you ever got it solved.

Thanks.

[QUOTE]and now the engine runs o.k. and the timing mark on the harmonic balancer does line up with the position where it should based on a 305 pointer, not the 350 pointer which I was sold (I was told they were all the same).

Yes---as I said in the original post, I pulled the distributor and turned the rotor shaft by one tooth to position the cap where it should set in relationship to the firewall, found top dead center on compression stroke on number 1 cylinder, and scribed a new timing mark on my harmonic balancer.

Sorry, missed that earlier statement.

So actually your timing was off because of the balancer mark. Unfortunately mine does read TDC properly. Looks like I have other issues.