[chrise321]

When I checked my initial timing on the 69 GTO I recently bought, the timing mark was off of the scale on the timing cover probable by 2 inches or more in the advanced direction. This was with the vacuum advance line off and plugged. When I tried to adjust it back towards 12 degrees, it would hardly idle. Someone else posted the same problem a while back and and someone told him that the harmonic balancer might have slipped on its rubber mounting. I decided to check if the mark was in the right location when #1 cylinder was at TDC, so I bought a piston stop and while turning the crank ccw to bring the piston back up to the stop, the balancer bolt actually came loose (obviously not torqued to 160 lbs.) Anyway I decided to take off the balancer to look at it and discovered it was an earlier model(64~67) 2-piece unit. The engine in my car is a 68 WT block with a 9-bolt waterpump and I was wondering if this harmonic balancer will work. It is not correct for this year engine but all of the belts line up and I don't think that the 2-piece balancer has the slipping problem of the 1-piece rubber style (correct me if I'm wrong). If it is ok to use, I will just reinstall it with the proper amount of torque on the bolt and continue my checks. Could it be that the timing mark on this style of balancer is in a different location than on the 1-piece balancer? I hope not because If I have to buy a new 1-piece style balancer it looks like I will also need new pulleys (at least crankshaft pulley) as well. If the mark does line up at TDC, could my problem be one of carburetor mixture and RPM adjustment to make it idle better closer to 12 degree initial timing? One more thing, I believe this car has a non-stock cam in it but I do not know the specs on it. It has a mild lopey sound but definitly not real radical.

[HWYSTR455]

One thing to keep in mind, if the engine has been run a while with the balancer loose, it could have boogered up the crank snout. I've never run an early balancer, but from chatter I've heard, they're junk. Personally, I'll never run a factory balancer again, because of all the slip, etc I've had with them. The newer aftermarket factory replacement balancers are better now, from what I understand, though I've never used one, and if you keep it under say 6000 RPM, you should be ok. As for the timing marks, yes, it's possible they're at different locations, personally I'm not sure, and it's also possible the timing cover is mounted slightly off. (Not sure how many degrees that would effect, but it could). I've never trusted the marks 100% anyway, and even chain stretch could effect the TDC verification process. Adding all that up can give you a variance of several degrees. When it comes to timing a street car, start with initial, then total, then play with advance. If your confident the carb is close to the target in initial adjustment, move the timing to where it idles well, gives good off-idle response, and forget the marks. Obviously, your doing this without any vacuum advance factors, which is the last thing to add to the equation. Back to the balancer question, IMO, get a later factory replacement one, and correct the pulleys if out of alignment. When you have the balancer off, mic the snout for runout....

[Shadowjack]

A '68 is a one-year-only early cover and late balancer. If you want to run the early balancer, get a '67 cover--the brackets are all the same, although you might need the '67 pulleys.

[engineer]

first off, if you are using a 67 balancer on a 69 setup, then yes you are correct in that the pulley setup must all be from a 67 or earlier. the 67 timing mark is on the hub, not the balancer weight so unless the hub loosened enough so it could move off the woodruff key, it can only be in one position. And yes, the early weights also had a rubber that could fail, it would only result in an unbalanced engine, with a lot of vibration but the timing did not change. now you could switch to the larger one piece but all the pulleys would have to be changed. If you looked at the crank, the keyway is good, the hub doesn't move on the keyway, and the rubber is intact on the weight then you are good to go. look for timing chain slip or something else.