Harmonic balancer questions

[jclays]

Have a 1966 28ft Californian express cruiser. Twin GM 350's possibly Crusaders. Not sure if the original engines where 283 or 327. Those however where originally Crusaders. Block castings on these engines are 1969 350's. Now my issue. I'm looking for a replacement harmonic balancer. Went to Napa auto parts picked up a balancer for a 1969 350 Chevrolet 6 3/4 inches in diameter. Looked pretty much identical. Took it to the boat and matched them up. Oops the original is a 6 1/4 inch not 6 3/4 inch. Need to head back in the morning and see if 6 1/4 inch is still available I understand that 6 3/4 and 8 inch are the common size. Maybe a 327 balancer??? The 6 3/4 inch wont clear the timing tab on my timing cover (welded on). What say you??
Thanks
Jim

 

[RicardoMarine]

Jim, if you don't mind spending $299, here's your 6-1/4" balancer.

If your immediate area has what's called a Engine Rebuilders Supply company, give them a phone call and ask about a good used 6-1/4" balancer.
We have one in our area, and they are generally a very good source for things like this.

Or......

Buy a new marked off 6-3/4" or 7" balancer (some are as little as $60 or $70).
(the marked off balancer will allow for a much more accurate and goof proof Ignition Timing TA check)

Then grind off the old timing chain cover tab, and install an add-on timing chain cover "tab" for the new balancer diameter.
(must be correct for the replacement balancer diameter)



NOTE: there are several diameter SBC balancers.... 6 1/4", 6 3/4", 7"... and 8".
The 6.6L (aka 400 cu in SBC) is not interchangeable with the other SBC's.

Personally, I'd not feel comfortable with changing balancers and/or tabs, without doing a PPS and verifying TDC with the new tab and/or balancer. If you do this, it would give you some peace of mind when it comes to Ignition TA.



Be sure to stake the new balancer on the inner and outer hubs so that you can later check to see if the two are remaining phased with each other.


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[jclays]

Couldn't find a 6 1/4 inch harmonic balancer anywhere. Thought of using the 6 3/4 but after re checking the engine compartment it looked like I would have a clearance issue against the front U shaped yoke style engine mount. Found a guy on the internet called the Damper Doctor online..All he does is harmonic balancers. He is rebuilding one for me today and will ship it out tomorrow morning. He says 6 1/4 inch Chevy is one of his popular rebuilds.