top end whine

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plattd
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Location: portland, OR

top end whine

#1

Post by plattd » Thu Jan 22, 2009 12:10 am

I've come by a 54 FL chopper with fishtails (loud) but even so I'm hearing an engine whine that's borderline annoying, especially when running slow, like through side streets. Hear it most when off the throttle, but that may just be less competition from the exhaust. When I walk my ears around the bike at idle, the whine seems to be coming from the top end, but I'm wondering what in there could make such a noise at those low RPMs. I'm new to these engines but not to 50s bike engines in general--I'm wondering what kind of noise and how much I can expect. Bike starts well, accelerates well, gear chest looks decent, generator gear has small amount of lash with idler--I dont want to put miles on this thing if the whine indicates a serious problem. Any thoughts welcome, and THANKS.

David



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Re: top end whine

#2

Post by FlatHeadSix » Thu Jan 22, 2009 12:43 am

David,
You already mentioned the most common cause of "whine" in a pan engine: generator gear/idler lash. You can rule this out with one or two easy checks (or both). 1.) Get a mechanics stethascope and place the probe against various places spots around the generator, placing it directly against either of the 2 mounting bolts which go thru the cam cover is most revealing. 2.) loosen all the generator mounting, straps and cam cover bolts, and add or delete shims under the generator, tighten everything up and listen again.

It could also be coming from the generator itself, dry or bad bearing.

let us know what you find

mike

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Re: top end whine

#3

Post by panhead_kicker » Thu Jan 22, 2009 12:44 am

While you'll want to hear from the more experienced folks, I'd have to say your generator is the culprit. I don't think there is anything in the top end to make a whine noise. Whine says "gears" to me. Would it hurt to pull the generator and run the motor to see if the whine disappeared? I think a little whine from the gen is typical. How much is "too much"; don't know. While you have it off you'd probably do well to check it over thoroughly.

Cotten
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Re: top end whine

#4

Post by Cotten » Thu Jan 22, 2009 2:06 am

I agree, of course, that generators are notorious for a whine.

But I have found that the usual cause for a truly loud and annoying whine is a "bolt-in" one-size-fitz-none aftermarket cam.

...Cotten

plattd
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Re: top end whine

#5

Post by plattd » Thu Jan 22, 2009 2:21 am

Hmmm, thanks all. I've got the gen out and will let you know how that test goes when the time comes. like when the oil tank is cleaned up and refilled.
And Cotton--you've got me thinking cam now. With gear chest cover off, I see the cam is an Andrews 'A'. So...
Tell me more, if you would--should I expect disaster or just annoyance? What about these cams make the whine?

David

Cotten
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Re: top end whine

#6

Post by Cotten » Thu Jan 22, 2009 3:01 am

David!

The Factory made gears as accurately as they could, but when variances demanded it, they would assign color codes to gears so that they could be matched together as a set.

Modern aftermarket suppliers figured they could just make one-size-fitz-all replacements, so a perfect match became a matter of luck.
A poor match could rattle or whine, depending upon the mesh of the gear teeth.

I have little experience with Andrews cams beyond replacing them.
Through the 80s and 90s, their gear was machined to a unique bore, so it could not be swapped for proper gearmesh to anyone's billet but theirs.
Its been many years, so perhaps they have changed, and a gear swap is now possible.

....Cotten

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Re: top end whine

#7

Post by mbskeam » Thu Jan 22, 2009 4:36 am

what is the cam lash you have now with the cam cover on?
take out the cam end play shim, wipe off the oil on the bearings and cam jurnals, take out the breather and dist drive gear, put cam in.
then with a finger in the lifter block hole can you slide the cam back and forth?
if not, your gear is to big you can get a diffrent pinion or cam gear, if it has any sort of back lash you will hear it click when it gets up to opperating temp

you want just short of no lash to just a slight drag on the cam when it is slid back and forth....
when you go small you will feel it and the same with to big....
when you get the right size you will feel it....
if you can find a shop that does old bikes see if you can borrow a gear or two, and buy the one that fits......

mbskeam

plattd
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Re: top end whine

#8

Post by plattd » Fri Jan 23, 2009 2:30 am

Thanks all for the valuable input. I pulled the tappets and did the end play test on the cam gear, minus thrust washer, cover bolted on. Felt pretty good, just a slight rub. BUT, I had noticed how tight it had seemed when under spring load and this sent me back to check the bushing/shaft clearance--guess what? Clearance is about .005, which to my understanding is about twice the max allowable. So I'm thinking the valve spring pressure is able to deflect the cam enough to jam it into too close a mesh with the pinion, giving me the whine (howl?) What do you think?

David

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