Harmonic balancer - SS350/300HP

[bheston]

I’m in the process of replacing my harmonic balancer because I thought it spun. This is a SS350/300 car.  I bought a new 8 inch “stock” unit from Heartbeat City. After pulling the old one, I noticed it was a 6 3/4 balancer and appears to have been originally painted blue. The timing marks are not aligned. The old small balancer has the timing mark offset from the keyway which is wrong for my car. I had to find TDC and put a line on the balancer.  The new larger balancer has the timing mark aligned with the keyway which is right for my car. The timing cover on the car is for a 6 3/4 balancer.

I thought all 350/300 were equipped with an 8 inch balancer? Will it be benificial to change the timing cover and use the 8 inch balancer? Safe to assume it won’t hurt anything?

[bheston]

Here is some more information.  I don't think I properly described the new 8 inch balancer.  The timing mark on the new balancer does not have the keyway and timing mark exactly aligned but they are much closer than the original.  Below is a picture of the old 6 3/4 balancer.  You can see evidence of if being painted blue at some point (late 70's donor?).  There is also a picture of the new 8 balancer.

 

[KevinW]

BH, yes the 69 350/300 hp engine is supposed to have the 8" balancer and timing cover.  The smaller 6 3/4" was used on the lower HP versions. You sure you have the 350/300 engine?  What is your engine codes stamped?

69s also had the offset timing mark due to emissions.  Nowadays, you just adjust timing to how well the engine runs and record where the timing mark is

[bheston]

Here is the stamp on the pad:

[Kelley W King]

I think the blue paint started in 77.

[z28z11]

Here is the stamp on the pad:

What on earth got after the pad ? Looks like a pneumatic scraper really took it apart -

Steve

[bheston]

Looks rough in the picture. I put some red/black marker on to enhance the contrast. Then I added extra contrast in photoshop to make it look clearer. It actually feels reasonably smooth to touch. My engine forensic techniques may be questionable 

[KevinW]

Yes, HA block is SS 350/300.  If you  have the 6 3/4 timing cover that got swapped at some point.  You should get the 8" but the 6 3/4 will work in a pinch if engine is still balanced.

[Kelley W King]

The 8 inch covers are a little hard to find. You can buy the aftermarket (most are chrome) with the bolt on marker and paint it orange. Not correct but hard to tell unless you know.

[bheston]

I bought an 8" cover and balancer from Heartbeat City.  Painted orange and ready to install (once the paint dries of course).  Not correct, but I have other things that are not correct so I'm not concerned.  I'm liberated from the burden of originality for the most part .  However, I do want to maintain the spirit of originality.

[69Z28-RS]

Looks rough in the picture. I put some red/black marker on to enhance the contrast. Then I added extra contrast in photoshop to make it look clearer. It actually feels reasonably smooth to touch. My engine forensic techniques may be questionable 

BHeston,  suggest that you use a little lacquer thinner on a rag and CLEAN all the paint/marker/etc off the pad, and THEN take the best high resolution photograph of the pad that you can take (NO photoshop), and then post here, so we can see what you really have...   

PS.  NEVER use any 'mechanical means' to clean what you suspect is an original stamped pad as that destroys the broach marks and thus destroys any remaining originality of the pad!!

[ko-lek-tor]

The 8 inch covers are a little hard to find. You can buy the aftermarket (most are chrome) with the bolt on marker and paint it orange. Not correct but hard to tell unless you know.

You don’t say? Funny, I have 5 of those covers and several balancers. I put them up on eBay for $9.99ea. and could not get one bid? Finally sold 1 balancer for $5

[Kelley W King]

Thanks B, now I know where to get one.

[KevinW]

The timing tab has to say AOR.  I sold one too cheap at a swap meet