67 BB Harmonic Balancer

[Dereck S.]

Trying to determine if the harmonic balancer on my 67 427/400 (no A/C, PS or other accessories) is correct for the car. Measurements of the mass ring are 7" OD x 1 3/8" thick. Based on this info can anyone confirm this is correct?

[Joe L.]

Re: 67 BB Harmonic Balancer

Trying to determine if the harmonic balancer on my 67 427/400 (no A/C, PS or other accessories) is correct for the car. Measurements of the mass ring are 7" OD x 1 3/8" thick. Based on this info can anyone confirm this is correct?

Dereck-----


It's correct. It's a GM #3860008. You might even find "008" STAMPED on the front of the balancer. Whether, or not, it's the correct dimensions for your application and I have little doubt it's the correct one. It's no longer available from GM.

[Dereck S.]

Re: 67 BB Harmonic Balancer

Thanks Joe, I'm scratching my head over a belt misalignment that's been present from day one. Visually, the alternator belt isn't in alignment with the water pump and crank pulleys. It's off by around 1/4". I confirmed I have the correct alternator mount bracket and large OD thin pulley for a non-A/C and non-PS engine. I decided to determine what was incorrect and fix it so I removed all the pulleys. I found that a hand-made 1/4" spacer was under the water pump pulley. Clearly a hack job. I then found that this was put there to get the water pump pulley to align with the crank pulley. I confirmed I have the correct 2-groove cast iron crank pulley. When I remove the 1/4" hack job spacer and install the water pump pulley on the pump shaft the alternator seems to be in alignment. I noticed however that the water pump pulley contacts the OD of the harmonic balancer. It appears that the balacer is correct based on your feedback however it seems like it is protruding forward and preventing the pulley from aligning as well as clearing the balancer. I have not pulled the balancer yet since I don't have puller and pusher tools. I'm at the point where it seems like the balancer is not fully seated against the timing chain sprocket or something on the crank is not right. Could there be an incorrect timing sprocket, crank, spacer, etc preventing the balancer from being properly positioned? This is proving to be a real challenge. Any thoughts?

[Joe L.]

Re: 67 BB Harmonic Balancer

Thanks Joe, I'm scratching my head over a belt misalignment that's been present from day one. Visually, the alternator belt isn't in alignment with the water pump and crank pulleys. It's off by around 1/4". I confirmed I have the correct alternator mount bracket and large OD thin pulley for a non-A/C and non-PS engine. I decided to determine what was incorrect and fix it so I removed all the pulleys. I found that a hand-made 1/4" spacer was under the water pump pulley. Clearly a hack job. I then found that this was put there to get the water pump pulley to align with the crank pulley. I confirmed I have the correct 2-groove cast iron crank pulley. When I remove the 1/4" hack job spacer and install the water pump pulley on the pump shaft the alternator seems to be in alignment. I noticed however that the water pump pulley contacts the OD of the harmonic balancer. It appears that the balacer is correct based on your feedback however it seems like it is protruding forward and preventing the pulley from aligning as well as clearing the balancer. I have not pulled the balancer yet since I don't have puller and pusher tools. I'm at the point where it seems like the balancer is not fully seated against the timing chain sprocket or something on the crank is not right. Could there be an incorrect timing sprocket, crank, spacer, etc preventing the balancer from being properly positioned? This is proving to be a real challenge. Any thoughts?

Dereck-----

All GM crank sprockets for a big block have the same thickness at the area where the balancer seats. All aftermarket ones I've seen do, too. I suppose it's possible that there are some out there that don't, though. It's also possible, I suppose, that someone installed a spacer between the balancer and the crank sprocket. This is not correct but, then, neither is a spacer on the waterpump flange. So, who knows what someone might have done for unknown reasons. It's also, of course, possible that the balancer was not installed so that it's fully seated against the crank sprocket. Sometimes, if there is a burr or "nick" on the crank snout or balancer orifice, the balancer will go on with great difficulty. At some point, someone may have decided that was enough and figured the balancer was "all the way home". It might not have been, though.

Are you sure that you have a GM #3854480 or 3906656 waterpump pulley? Either of these pullies should not contact the balancer ring. In fact, the same pullies were used for applications using an 8" balancer. So, if they contact a 7" balancer, just imagine what they'd do with an 8" balancer.

[Wayne M.]

Re: 67 BB Harmonic Balancer

Dereck-----


It's correct. It's a GM #3860008. You might even find "008" STAMPED on the front of the balancer. Whether, or not, it's the correct dimensions for your application and I have little doubt it's the correct one. It's no longer available from GM.

Joe -- here's a 7-inch balancer I have of the exact dimensions that Dereck provides. Probably off a '65 passenger 396/325 hp 4-sp. Pic shows a cast of 3860060, but I believe it was concluded on the DB a few years ago that this was just the HUB casting number, and that 3860008 would have been the hub/ring assembly. Nothing stamped on the front face on this one.

[Dereck S.]

Re: 67 BB Harmonic Balancer

Guys,
I confirmed a 7 1/8" OD water pump pulley. It has no part number on it. There is a reinforcement/stiffener cup welded to the inside of the pulley. This would space out the pulley on the pump. I'm assuming this was the change from GM 3854480 to 3906656. Once installed on the pump it does come very close to the pump casting. Based on your feedback regarding a common pump pulley for both the 7" and 8" OD balancers. This can only mean that the balancers once installed on the crank is behind the pump pulley back plane. This is also the only way the belt can align with both pulleys. Therefore, I've concluded that the balancer is not located properly in the axial direction. My next step is to purchase a push-on tool and attempt to ensure the balancer is fully seated. If this is the issue I'm done and everything else falls into place. If this is not true than I'll pull off the balancer and look for part number on it confirm it is correct, look for a spacer on the crank, and if possible visually look inside the timing cover around the seal for anything else causing the improper positioning of the balancer. Wayne, any way you could send a photo of your balancer from the front. I noticed I have a step between the center hub and the mass ring. I want to confirm this is also typical. It will take a few days to get the push-on tool. Would it be a mistake to attempt to torque up the bolt and push-on the balancer? Provided I did not exceed the recommended torque on the bolt. I'll also post some photos of where my balancer is relative to the water pump.

[Joe L.]

Re: 67 BB Harmonic Balancer

Guys,
I confirmed a 7 1/8" OD water pump pulley. It has no part number on it. There is a reinforcement/stiffener cup welded to the inside of the pulley. This would space out the pulley on the pump. I'm assuming this was the change from GM 3854480 to 3906656. Once installed on the pump it does come very close to the pump casting. Based on your feedback regarding a common pump pulley for both the 7" and 8" OD balancers. This can only mean that the balancers once installed on the crank is behind the pump pulley back plane. This is also the only way the belt can align with both pulleys. Therefore, I've concluded that the balancer is not located properly in the axial direction. My next step is to purchase a push-on tool and attempt to ensure the balancer is fully seated. If this is the issue I'm done and everything else falls into place. If this is not true than I'll pull off the balancer and look for part number on it confirm it is correct, look for a spacer on the crank, and if possible visually look inside the timing cover around the seal for anything else causing the improper positioning of the balancer. Wayne, any way you could send a photo of your balancer from the front. I noticed I have a step between the center hub and the mass ring. I want to confirm this is also typical. It will take a few days to get the push-on tool. Would it be a mistake to attempt to torque up the bolt and push-on the balancer? Provided I did not exceed the recommended torque on the bolt. I'll also post some photos of where my balancer is relative to the water pump.

Dereck----

Your waterpump pulley is the correct OD. I measure it at 7-3/16", but I'm sure were talking about the right piece. I think both of the pullies had the inner reinforcement. There was a change in the "hat" configuration of the pullies but that did not affect functionality. When installed, the rear of the pulley does come very close to the pump casting.

Yes, the forward edge of the balancer ring should be rearward of the plane of the rear of the waterpump pulley. If this is not the case in your situation, then there is a problem with the balancer installation or something related to it.

You can try to move the balancer further onto the crank snout by rotating the balancer center bolt (with the engine prevented from rotation). However, I doubt that you'll get any movement within the torque limit of the bolt. Then, as you've surmised, the next step will be removal of the balancer.

The photos will help.

[Wayne M.]

Re: 67 BB Harmonic Balancer

...... any way you could send a photo of your balancer from the front. I noticed I have a step between the center hub and the mass ring. I want to confirm this is also typical. ....

Here's a shot of the front of the 7" balancer. The raised face in the center is 0.125" high. I'm not saying this is correct for your '67, but I don't think they made many variations on this.

[Joe L.]

Re: 67 BB Harmonic Balancer

Here's a shot of the front of the 7" balancer. The raised face in the center is 0.125" high. I'm not saying this is correct for your '67, but I don't think they made many variations on this.

Wayne-----


I don't think that feature changed for the 7" balancer.

[Wayne M.]

Re: 67 BB Harmonic Balancer

Let's go back and talk about water pump pulleys. Pic shows the "245" small block hi-perf, @ 7_1/8" OD, per parts catalog. (I measure about 1/32" less, but let's not quibble). Notice the pressed on forward groove (lip at base of cone). No part # on this one (as I believe the case for all factory production).

Sorry I don't have pic handy of the '656' that replaced the '480' sometime in calendar '66 (for service, anyway). Hard to measure dia. when on car with belts, but I can say there's no more than about 40-thou clearance between it and the the iron crank pulley. Is this the one Joe measures at 7_3/16" OD ? The '480' and '656' have two spot weld beads at the base of the front cone (but no front lip, per the '245'); and, if you run your finger on the inside (water pump side) it is flat, not double-valley curved to match the outside belt groooves, as is the '245'.

Just trying to establish if Dereck is using the SB '245' instead of the BB '656' ?

[Joe L.]

Re: 67 BB Harmonic Balancer

Let's go back and talk about water pump pulleys. Pic shows the "245" small block hi-perf, @ 7_1/8" OD, per parts catalog. (I measure about 1/32" less, but let's not quibble). Notice the pressed on forward groove (lip at base of cone). No part # on this one (as I believe the case for all factory production).

Sorry I don't have pic handy of the '656' that replaced the '480' sometime in calendar '66 (for service, anyway). Hard to measure dia. when on car with belts, but I can say there's no more than about 40-thou clearance between it and the the iron crank pulley. Is this the one Joe measures at 7_3/16" OD ? The '480' and '656' have two spot weld beads at the base of the front cone (but no front lip, per the '245'); and, if you run your finger on the inside (water pump side) it is flat, not double-valley curved to match the outside belt groooves, as is the '245'.

Just trying to establish if Dereck is using the SB '245' instead of the BB '656' ?

Wayne-----


I re-measured the 3906656 and I come up with 7-1/8" now, too. I don't know where I got the 7-3/16" dimension, but I've corrected my notes on the pulley OD.

Attached are photos of a 3906656. If I recall, only the hat section is different on a 3864480. In any event, the 3906656 has no part number embossed on it, but I'm certain this is a 3906656 since it's NOS in-the-box.

[Dereck S.]

Re: 67 BB Harmonic Balancer

Here's some pictures to help communicate the issue. One pic is of the water pump and crank pulleys. I cleaned up the crank pulley. I believe the water pump pulley agrees with your feedback. The other pic shows the axial location of the balancer mass ring relative to the timing cover degree clip. This may help with the determination of proper axial location of the balancer. The third pic shows the water pump pulley held on by hand and how it interferes with the balancer. This clearly shows the balancer needs to move around 3/16" or so towards the engine. I did try to move the balancer by tightening the bolt but was unsuccessful. It felt pretty solid. I was afraid of shearing off the bolt. I don't need that problem. I'll have a push-on tool in three days. I can't imagine that there is a spacer under the balancer or that there is something different with the crank or timing sprocket. If I do need to pull the balancer off which is very likely I'll take some length measurements. Maybe I'll see something in the timing cover area. I'm becoming more conserned about what I might find. I've driven the car this way for a long time with no issues. However, it bugs the hell out of me that it wasn't properly done. We'll figure it out. Let me know your thoughts.
Dereck

[Joe L.]

Re: 67 BB Harmonic Balancer

Here's some pictures to help communicate the issue. One pic is of the water pump and crank pulleys. I cleaned up the crank pulley. I believe the water pump pulley agrees with your feedback. The other pic shows the axial location of the balancer mass ring relative to the timing cover degree clip. This may help with the determination of proper axial location of the balancer. The third pic shows the water pump pulley held on by hand and how it interferes with the balancer. This clearly shows the balancer needs to move around 3/16" or so towards the engine. I did try to move the balancer by tightening the bolt but was unsuccessful. It felt pretty solid. I was afraid of shearing off the bolt. I don't need that problem. I'll have a push-on tool in three days. I can't imagine that there is a spacer under the balancer or that there is something different with the crank or timing sprocket. If I do need to pull the balancer off which is very likely I'll take some length measurements. Maybe I'll see something in the timing cover area. I'm becoming more conserned about what I might find. I've driven the car this way for a long time with no issues. However, it bugs the hell out of me that it wasn't properly done. We'll figure it out. Let me know your thoughts.
Dereck

Dereck-----


Well, as they say, a picture is worth a thousand words and that's definitely the case here. Your balancer is WAY SHORT of being fully seated against the crank sprocket and I mean WAY SHORT! I would say it's about 1/2" to 1" short. I can't imagine ANY available crank sprocket to cause that much of a discrepancy.

[Dereck S.]

Re: 67 BB Harmonic Balancer

I don't see that as a possibility at least for this crank. I reached into the end of the crank to see where the crank end is relative to the washer seat face on the balancer. The crank is inboard of the washer seat face by less that a half an inch. May even be closer to 1/4". This represents the absolute maximum the current balancer can be moved inboard until the end of the crank is flush to the washer seat face. Once that happens you get no bolt clamp. In addition, in order to get the pulleys to align the balancer only needs to go in around 1/4" or so. Any more than that and It's out of alignment the other way. It may very well be the wrong balancer as it relates to the hub length. I'll pull it off tomorrow if possible. I hope it's not a crank issue.
Dereck

[Joe L.]

Re: 67 BB Harmonic Balancer

I don't see that as a possibility at least for this crank. I reached into the end of the crank to see where the crank end is relative to the washer seat face on the balancer. The crank is inboard of the washer seat face by less that a half an inch. May even be closer to 1/4". This represents the absolute maximum the current balancer can be moved inboard until the end of the crank is flush to the washer seat face. Once that happens you get no bolt clamp. In addition, in order to get the pulleys to align the balancer only needs to go in around 1/4" or so. Any more than that and It's out of alignment the other way. It may very well be the wrong balancer as it relates to the hub length. I'll pull it off tomorrow if possible. I hope it's not a crank issue.
Dereck

Dereck-----


It may be only 1/4" off, but it sure looks like more than that to me.