DZ harmonic balancer VS LT1 harmonic balancer

[PACE&Z2869]

Hello. Can anyone tell me if a DZ 302 balancer and a LT1 balancer are interchangable? I'm wondering if the timing marks are in the same location. The only visable difference I've noticed is the 3 raised portions on the DZ balancer vs the flat surface on the LT1. I have not had a chance to hold the 2 together to compare if the timing marks are the same. Any help appreciated. Thanks.

[JohnZ]

The DZ balancer has the timing index line on the inertia ring about 10* counter-clockwise from a straight line extended from the hub keyway slot through the center of a pulley bolt hole, as the '69 DZ used the new long water pump accessory drive; '68 and earlier balancers had the timing index line directly on that line, as they used the earlier short water pump accessory drive system. An LT-1 balancer should also have the timing index line located in exactly the same place as the DZ balancer, as it also used the long water pump layout.

[Pacecarjeff]

The DZ balancer was part# 7708, the LT-1 balancer was# 7712
I have held them up together, and I could not find a single difference.
The casting numbers were even the same. The timing marks were identical.

Of course- Not including the original DZ style with the long legs on the face. That one is unique.

[RamAirDave]

What about HB #3942538?  What was its original application, and can it be used in place of the DZ HB?



dave

[Pacecarjeff]

538 balancer was used starting in 1970. That is the one I was talking about before. 7708/7712

It also had many other apps - it was used for quite some time in the 70's

[RamAirDave]

Thanks, Jeff

I was wondering if there was any physical difference since it is very close to the timing chain cover, and wasnt sure if that was right or not.

dave

[Pacecarjeff]

The 538 balancer (7708-C) is the direct replacement for the original 7708-M -used only on the 69 Z/28.
Or even the 538 (7712) from the Lt-1

HB 538  came with quite a few different timing mark locations, depending on the part number that was stamped. Some were so close as to not really matter.
It will fit just fine on your car.

[lynnbilodeau]

I realize this is a very old thread, but there is a difference betweent the 7708 and the 7712.  GM didn't use different id numbers just to confuse us.  If there is a different number, there is usually a difference, even if they are interchangeable.

They both start out from the same casting, as noted above.  Timing marks are in the same place, and yes, they would interchange.

The machining is a little different.  The 7708 has a lip machined into the back side from the outside in, making most of the outer ring about 1/16 inch thinner.  The machining starts just outside the elastomer (sp?).  It would be very easy to make a 7708 out of a 7712 with a lathe.

Can post a pic of them side by side if anyone wants to see the difference.