Author Topic: Harmonic balancer - SS350/300HP  (Read 835 times)

bheston

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Harmonic balancer - SS350/300HP
« on: April 25, 2018, 12:28:08 AM »
Iím 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 ďstockĒ 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 wonít hurt anything?

bheston

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Re: Harmonic balancer - SS350/300HP
« Reply #1 on: April 25, 2018, 10:46:43 AM »
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

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Re: Harmonic balancer - SS350/300HP
« Reply #2 on: April 25, 2018, 10:52:08 AM »
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

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Re: Harmonic balancer - SS350/300HP
« Reply #3 on: April 25, 2018, 10:59:19 AM »
Here is the stamp on the pad:

Kelley W King

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Re: Harmonic balancer - SS350/300HP
« Reply #4 on: April 25, 2018, 11:43:17 AM »
I think the blue paint started in 77.
69 Z28 RS Scuncio Hi Performance
69 SS L78
67 SS Chevelle
64 Corvette
66 GTO Tiger Gold
77 Trans Am Special Edition

z28z11

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Re: Harmonic balancer - SS350/300HP
« Reply #5 on: April 26, 2018, 03:40:24 AM »
Here is the stamp on the pad:


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

Steve
1968 Z28 M21/U17 BRG/W
1969 Z28 X77/M20/VE3 LeMans/W
1969 L78 X66/N66 Cortez/BVT
1969 Z11 L48/M35/C60/C06

bheston

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Re: Harmonic balancer - SS350/300HP
« Reply #6 on: April 26, 2018, 09:41:16 AM »
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  :o

KevinW

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Re: Harmonic balancer - SS350/300HP
« Reply #7 on: April 26, 2018, 10:26:18 AM »
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

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Re: Harmonic balancer - SS350/300HP
« Reply #8 on: April 26, 2018, 12:53:00 PM »
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.
69 Z28 RS Scuncio Hi Performance
69 SS L78
67 SS Chevelle
64 Corvette
66 GTO Tiger Gold
77 Trans Am Special Edition

bheston

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Re: Harmonic balancer - SS350/300HP
« Reply #9 on: April 26, 2018, 01:03:05 PM »
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 ;D.  However, I do want to maintain the spirit of originality.

69Z28-RS

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Re: Harmonic balancer - SS350/300HP
« Reply #10 on: April 26, 2018, 01:09:29 PM »
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  :o

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!!
Gary W / 09C 69Z28-RS, 72 B 720 cowl console rosewood tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe, '70 Mach I 
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ko-lek-tor

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Re: Harmonic balancer - SS350/300HP
« Reply #11 on: April 26, 2018, 04:48:32 PM »
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 donít 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
James to strangers, Bentley to friends
1969 SS/RS 396 coupe Hugger Orange X22 712 bought in 79
1969 SS 350 coupe LeMans Blue 713 bought in 79(sold)
1969 307 4spd. coupe Daytona Yellow 711 bought in 85

Kelley W King

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Re: Harmonic balancer - SS350/300HP
« Reply #12 on: April 26, 2018, 06:28:40 PM »
Thanks B, now I know where to get one.
69 Z28 RS Scuncio Hi Performance
69 SS L78
67 SS Chevelle
64 Corvette
66 GTO Tiger Gold
77 Trans Am Special Edition

KevinW

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Re: Harmonic balancer - SS350/300HP
« Reply #13 on: April 26, 2018, 11:54:42 PM »
The timing tab has to say AOR.  I sold one too cheap at a swap meet :(