I recently (a couple months) marked TDC on my balancer when I had the motor apart. The balancer didn't have any marks on it previously. I've driven it hard a couple of times since I got the car running well about two weeks ago. The balancer is not keyed to the crankshaft. I went to check timing tonight and it seems it's slipped about 20*. Is this normal for non-keyed balancers?

As far as why it doesn't have a key, the motor is a modern LT1. The crank had a slot for a key but didn't have one and the balancer had no slot to accept one. I used a grinder to make a key slot on the balancer hub and put a key in the crank, but wasn't ever able to get them matched up correctly so I took the key out. I figured if that's the way they come stock on LT1s, then it'd be OK to leave it that way.

If this is all normal, is there anyway I can accurately shoot timing without having to remark TDC every time I want to take a reading?

 

You might try posting over in the C-4 section or Engine Mods section, those guys have a lot more experience with modern engines.

 

Yeah, I've posted this in both. Funny thing is I tend to get just as good if not better responses here anyways.

 

First of all: There must be a key between Balancer and crankshaft... what funny balancer you have there (sorry, but...)? Without a slot for key and without any TDC-marks? There should at least be one straight mark for TDC (whereas there is a complete scale on the more expensive units).

Anyway... I have bought a new standard balancer (with key slot and TDC-mark) for my 350 rebuilt. And guess what happened: That damned thing slipped anyway. The rubber between hub and outer ring just said goodbye to the outer ring.

There are 2 possible reasons for that:
1) The unit simply had a quality problem (it was 60$ at SUMMIT I think)
2) The unit was too small (6,75" diameter). It was same size as on my previous Goodwrench motor. BUT... I have installed a more agressive cam and higher CR (9,3:1), gaining 320hp. Now if you look at the HO crate-engines, they all have larger ballancers (8" I believe) that can withstand the greater vibrations of the crank.

After I realized my outer ring walking, I remarked the ring to TDC but also put a mark onto the crank pulley (which is connected to the hub of the ballancer and cannot - given an existing key - walk). This way I can realize any further movement of the outer ring and also adjust spark advance with the pulley mark if need be.

Regards,
Thomas

 

One thing the manufactures could do to make is much easier to detect slippage would be have a mark on the inner hub of the balance so you could see if it has moved, may not detect a minor slip but you would def see a 20 deg movement. I think the LT1's have a cam sensor for timing so no balancer marks needed but I am not sure? :confused: I do know they have no dist cuz the LT1 intake on my Formula was retro fitted and had to have a dist hole cut in it.


[Modified by Fevre, 10:09 AM 2/20/2003]

 

I had a 6" balancer slip as well. Unfortunately didn't catch it in time and it rubbed a pinhole into the timing cover. :nopity

 

I'd say any slippage is normal - for a balancer that is about to be thrown away!
I never heard of a balancer without a key, but if that 's the case, they must install it with loctite or something. WHen the outer ring slips, it means there is othing really holding it in place, and it is only a matter of time before it falls off! Usually not a good thing. Joe

 

Hello Jason,
Havn't torn into an LT-1 but the missing dampner key sounds nonsensible. :bs
My shark gets Fluidampr (Streetdampr) and nothing else. You can E@mail them with your problem at support@vibratech.com. My guess is they'll have a fix for you (yea something to sell you also). :thumbs:
You need a piston stop tool to accurately find TDC on #1. Be careful turning the engine if you haven't used a piston stop before. Remove all your spark plugs and turn the engine "slowly" as you could hole a piston top or bend the stop tool. This is the most accurate method to adjust your timing tab/pointer for TDC I know of. Good luck. :lol:

 

The LT1 hub is a press fit, no key. Here is the service manual info
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Crankshaft Balancer and Hub Replacement
Removal Procedure
Tool Required
J 39046 Crankshaft Hub Remover/Installer

Raise and suitably support the vehicle. Refer to SECTION 0A.
Remove the accessory drive belt. Refer to Drive Belt Replacement . Remove the crankshaft balancer bolts.
Remove the crankshaft balancer.
Match mark the crankshaft hub to the engine front cover.
Do not crank the engine over after match marking the crankshaft hub and the engine front cover. Rotating the crankshaft will cause misalignment of the crankshaft balancer, to the crankshaft, possibly resulting in engine imbalance.



Remove the crankshaft hub bolt and the crankshaft washer.
Remove the crankshaft hub using the J 39046 .
Installation Procedure
Tool Required
J 39046 Crankshaft Hub Remover/Installer





Install the crankshaft hub using the J 39046 .
If the engine should accidentally be cranked over after match marking the hub and the engine front cover, install the crankshaft hub as follows:
Set the number 1 piston to the top dead center.
While viewing the crankshaft from the front. Verify that the keyway of the reluctor ring is properly orientated with the key of the crankshaft. Also verify that the ring is completely seated against the crankshaft sprocket.
Install the crankshaft hub with the cast arrow on the hub in the 12 o'clock position.
Install the crankshaft hub washer and the bolt. Tighten
Tighten the crankshaft balancer hub bolt to 100 N·m (74 lb ft).


Important
If the balancer is replaced, a new balance weight of the same size must be installed on the new balancer in the same hole locations as the old balancer.


Install the crankshaft balancer.
Install the crankshaft balancer bolts. Tighten
Tighten the crankshaft balancer bolt to 85 N·m (63 lb ft).