Timing issue / yellow sparks by water pump / fly wheel

[Joe L.]

Re: Timing issue / yellow sparks by water pump / fly wheel

I wanted to close out this post. The sparking issue noted above was due to a missing harmonic balancer bolt and the balancer had walked forward and started to rub on the water pump pulley. Once reparied the dwell and timing could be set and the car is running fine. I want to thank everyone for their posts and Central New Jersey NCRS Chapter President for putting me in touch with Howard and Patick Welch who fixed the harmonic balancer for me quickly.

Richard------


A couple of things: I do not understand how the harmonic balancer "walking forward" due to a lack of a center bolt could cause the timing problem you had. The balancer is KEYED to the crankshaft snout and even if it moved forward, it could not rotate.

Second, even if the balancer center bolt is missing, there should be enough interference fit between the balancer and the crankshaft to prevent the balancer from moving forward. In fact, this interference fit is necessary for the balancer to function properly, aside from the issue of its retention to the crankshaft. So, if a balancer moves forward on the crankshaft, more needs to be done than simply pressing it back in position and installing the bolt.

[Stuart F.]

Re: Timing issue / yellow sparks by water pump / fly wheel

FWIW, when I recently went to bar my L-76 (327/340hp) over to do a valve adjustment, I too found my center bolt loose. My engine is still untouched @ 44k miles, so it's been that way since the day I took delivery in 63 or gradually loosened over the years. I have not had any issues with it.

Stu Fox

[Richard K.]

Re: Timing issue / yellow sparks by water pump / fly wheel

Joe - I do not believe the timing issue and harmonic balancer issue are related. I was having trouble with the timing, (I think I did not have the distributor tightend down properly and it moved) after I had just tuned it up. When I went to reset the timing is when I saw the sparks and did not want to run the engine in that condition.

The harmonic balancer did not move / spin out of postion since the keyway was still in place. I can say for certainty the back of the water pump pulley was rubbing against the front of the harmonic balancer. Now with the bolt in place there if clearly more clearance between the two. I will keep on an eye on it and make sure it does not start to move again.