67 BB Harmonic Balancer

[Joseph K.]

Re: 67 BB Harmonic Balancer

Derick,
I agree with Joe the balancer is either not in all the way or it is the wrong one. I went through this before but I had the complete opposite. The balancer went in to far. It turned out to be the length of the snout that goes in to the timing chamber.

[Wayne M.]

Re: 67 BB Harmonic Balancer

Dereck --- here's two pics and some measurements to help you to compare. This is a 396 2-bolt 3855961 block I have, with the '6223' forged crank. Dimensions should be the same for your 427, probably with crank '7115'.

Crank balancer bolt and thick washer. Bolt alone, 19_1/2 turns to bottom in the crank with threads still exposed at the bolt head. Add the thick washer and it compresses against the nose in 18_3/4 turns.

7" dia. balancer hub length, 55 millimeters [mm] (@ 25.4 per inch) measured internally from thick washer contact surface to inboard end of hub that contacts the crank sprocket.

Length of crank 'nose' from face of sprocket to front face (with bolt hole) is 52 mm.

[Dereck S.]

Re: 67 BB Harmonic Balancer

Mystery solved,
I pulled the balancer off and found that the end of the crank had flowed/plowed material on the ID of the balancer snout bore. This stopped the balancer from properly being seated on the timing chain sprocket. I measured (using a digital mic) the length of the balancer from washer seating face to snout end and measured 55.4mm. I also measured the length of the crank end to the face of the timing chain sprocket face. This measured 52.3mm. Both these dimensions agree with what Wayne provided. Attached are two images. One shows the dig mark on the balancer bore ID. The other shows untouched paint overspry on the end face of the balancer that should have some evidence of contact (fretting) with the timing chain sprocket. This suggests that the balancer was not properly seated. Now that I know that I have the correct parts I plan on blending the burr on the end of the crank and blending the flowed metal and ridge on the balancer bore. I can't thank you guys enough for all the help and critical information you provided to help me resolve this issue.
Dereck

[Joe L.]

Re: 67 BB Harmonic Balancer

Mystery solved,
I pulled the balancer off and found that the end of the crank had flowed/plowed material on the ID of the balancer snout bore. This stopped the balancer from properly being seated on the timing chain sprocket. I measured (using a digital mic) the length of the balancer from washer seating face to snout end and measured 55.4mm. I also measured the length of the crank end to the face of the timing chain sprocket face. This measured 52.3mm. Both these dimensions agree with what Wayne provided. Attached are two images. One shows the dig mark on the balancer bore ID. The other shows untouched paint overspry on the end face of the balancer that should have some evidence of contact (fretting) with the timing chain sprocket. This suggests that the balancer was not properly seated. Now that I know that I have the correct parts I plan on blending the burr on the end of the crank and blending the flowed metal and ridge on the balancer bore. I can't thank you guys enough for all the help and critical information you provided to help me resolve this issue.
Dereck

Dereck----


Thanks for the feedback; it's very helpful. What you found is exactly what I most expected and described in my second post in this thread. Your solution to it is the correct one, too. Dress the crank so that ALL of the "expanded diameter" due to the "ding" is removed. Also, lightly dress the scored area in the balancer snout with fine grit sand paper or crocus cloth.