Packard Forum Index » Modification Discussion

Has anyone ever attempted to use a more modern harmonic balancer on their L8? as many of you I am planning to build my car up pretty far (for an L8 Packard that it) and I would like to get a bigger better harmonic balancer for it to better keep the vibrations down. I know many of you will say I do not need it but as the plan stands right now I will be likely spinning the engine close to twice its stock 2000 RPM power and torque peak and I don't really want to find out if my crank can outrun my car when it drops out of my oil pan.

If you do try one, here is a starting point. A former poster recommended Ford units several times for those wanting to add AC to their cars and needed a drive pulley.

As for your air conditioning, try a racing balancer from a 302 Ford that has removable weights inside. It fits right on the Packard crank, both straight eights and V8's. So does 3.8L Fords, 3.8L Buicks....


I don't know if anyone actually tried one or what if any extra work might be needed for the seal etc. He said the Ford units have an assortment of bolt on removable/interchangeable pulleys and one could mix and match to find a combination that would work on their car.

Yes, anything can be made to fit anything with enough effort. With enough time and money, I could the Ford fit, just not close to a bolt-on.

No, there may be some which will fit, but not those I tried. The small block Ford and those other dampers mentioned aren't even close to fitting the Packards.

The small block Ford et al dampers have the same crankshaft snout OD as the Packard, but those I tried won't physically fit anywhere else. The V8 Packard has that cone-shaped extension which pushes the damper ring and front pulley out in front of the engine. The Ford damper is flat and hits the timing extension on the front cover.




Also, the Ford has a smaller damper shaft OD than the Packard and would thus require a custom front seal.

Maybe, go to the source. For a price, Fluidamper, ATI and another CA hot rod outfit will build custom hubs for the Packard crankshaft to bolt on any of their race dampers.

jack vines

That is good information and glad to know that someone actually tried Turbopackman's recommendation to find it didn't work.

Another thing to cross off the list of possibilities so we are back to no AC pulleys other than finding an old 53-4 factory or aftermarket for inline 8's and only Nordstrom's repro for the V8.

I know absolutely nothing about this and perhaps shouldn't even be jumping in but if the pulley is that hard to locate, what are the options for making one (or more). Is the original stamped steel or cast? Could it be turned from a billet? Do we have the critical dimensions? Plenty of machine shops around looking for work.

The 53-4 factory AC crank drive pulley was two groove, cast, and bolted onto the vibration damper with a couple of bolts over the PS pulley. IIRC, there were some spacers or washers also involved. Diameter was roughly 6 inches or about an inch less than the PS and fan pulleys.

I doubt there would be enough sold to make it worthwhile for any production so perhaps a one off could be turned as needed for a reasonable price if someone were interested in doing it. The need for the original two grooves is debatable with a modern Sanden compressor so doing a single groove would probably simplify things a bit.

I have no idea what is involved in turning such an item on a lathe but Nordstrom seems to have successfully done it for the V8. Pricy though. Too bad those won't work for the older engines.

I'm almost wondering since the older pulleys bolt on with two bolts if an adapter plate of some sort could be made to locate properly on the damper and bolt on. Once that was fastened then a standard bolt on brand X pulley could be bought and fastened with more bolts to that adapter. Seems like making a couple of bosses or recesses on round stock and drilling and tapping some holes in a relatively flat piece of metal would be easier and cheaper than turning a complete pulley -- but I've been known to not see the obvious so probably more complicated than I think and balancing the combination might be a problem.

I think some caution should be excised here.
My understanding of the function of the harmonic balancer is that it dampens out torsional vibration in the crankshaft to avoid crankshaft breakage. I am not sure that it affects the engine vibration felt in the car however I am already way out of my depth.
This subject needs some engineering input from someone with specialist expertise in the field.
I am not sure that just fitting a bigger and better harmonic balancer is the way to go.

I see that Jack has tried the Ford pulley without success, on a V8 I think? I also note that Turbopackman specified particular Ford pulleys to use. See Post #26 in this thread and using them on the straight eights.

David, I am by no means an expert on engine harmonics but from what I do understand the balancer must be reasonably matched to the operating RPM of the engine. One that is set up to work with the 2000-2500 RPM range of the post war L8 is likely fine for that range, in my build I am attempting to stretch that to 4000-4500 RPM if possible and I feel that the stock style balancer wont be up to the job.

In the V8 Chevy world they have 2 common balancers (6 inch and an 8 inch if memory serves) the 6 inch was generally fitted to the 327 and smaller engines which had a stronger stiffer (all other factors equal) crank due to more overlap between the rod and main journals in the casting/ forging thus creating a crank less prone to flex where as the 350 and 400 CI engines (though the 400 was externally balanced) had the larger balancer, less overlap of the main and rod journals more flex and vibration equals the need for a bigger/ heavier balancer.

In the L8 engines where you have a proportionately long stroke, IE my 327 has a longer stroke than a 427 Chevy it will be more prone to flex and vibration than say a shorter stroke 288 or a more modern oversquare engine (big bore short stroke). Drag racers tend to use the smallest balancer available myself included when I ran small block Chevy engines due to the reduced rotating mass (think lightened flywheel)they were able to rev faster thus getting you into your power band quicker during launch and as you went through the gears. In the L8 no matter what I do it will never be a quick revving engine in the modern sense so I am not as concerned with the rotating weight as I am keeping the potentially severally damaging harmonics at bay.

I am a racer at heart as many of you know and in the racing world any engine that was slightly warmed over from stock it was advised to use a more sophisticated balancer that a stock cast two piece unit with a rubber isolater between the two. Properly controlling engine harmonics will increase power and longevity in any engine out there.

In 1951 Packard issued a service bulletin about a vibration sometimes encountered in Ultramatic cars between 80 and 90 mph. The problem was addressed with a brace on the bellhousing. Apparently some folks expected to drive that fast and Packard agreed.

With the normal 3.54 axle in the models mentioned that is cranking 3900 rpm. 4250 if it had the 3.9 axle some of the early cars had. I think you might be underestimating those old engineers. All of those engines had a high class fluid suspension damper in two different sizes. Oddly, the nine main bearing engines had the big one. I'm sure they knew that most folks would not rev them near the rating, but that doesn't mean they didn't design to sustain the rating.

The later L8s were all rated at 4000. That doesn't mean they couldn't turn faster--the breathing on an L head becomes so poor that the power falls off after that.