Reducing cam bore ID in an aluminum cam pulley?
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Reducing cam bore ID in an aluminum cam pulley?
I had to remove a DOCH Fiat ex cam pulley because it was not running "true". The pulley OD, and the timing belt, was wobbling by about 20-30 thou causing a pulsating belt whining noise.
The problem seems to be that the cam boss bore in the aluminum pulley is about 20 thou larger than the cam boss, permitting off-center installation.
Could I "dimple" the pulley to reduce clearance? The cam is in the engine, but I have another cam box I could use to true up the pulley before bolting on the engine.
This is the best available aftermarket stuff for my application.
Thoughts?
The problem seems to be that the cam boss bore in the aluminum pulley is about 20 thou larger than the cam boss, permitting off-center installation.
Could I "dimple" the pulley to reduce clearance? The cam is in the engine, but I have another cam box I could use to true up the pulley before bolting on the engine.
This is the best available aftermarket stuff for my application.
Thoughts?
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Re: Reducing cam bore ID in an aluminum cam pulley?
https://www.mcmaster.com/foil-shim-stoc ... m-stock-6/
Perhaps this type of material could be used on the end of the cam to incrementally increase the OD?
Perhaps this type of material could be used on the end of the cam to incrementally increase the OD?
https://www.semasan.com/breaking-news-archives?utm_campaign=DrivingForce_DF272&utm_content=SeeAllLeg
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Re: Reducing cam bore ID in an aluminum cam pulley?
Machinist solution...
Bore cam pulley and sleeve
Mechanic solution
Like Kevin said shim stock.
Bore cam pulley and sleeve
Mechanic solution
Like Kevin said shim stock.
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Re: Reducing cam bore ID in an aluminum cam pulley?
What englertracing said. They both will "work" but one will be repeatable, and the other is a kludge.
Re: Reducing cam bore ID in an aluminum cam pulley?
Option #3 (the aerospace solution)...nickel or hard chrome plate the ID undersize, then hone to the desired size.
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Re: Reducing cam bore ID in an aluminum cam pulley?
The next Captain Obvious move to check both cams and sprockets ("pulley").
If the sprockets are consistent in ID then...
Perhaps closer examination of the camshaft is called for, particularly the journals.
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Twenty thousandths of an inch is close to .5mm (FIAT is metric). A novice machinist could easily mistake graduations and this calls into question the other measurements on the cam.
If the sprockets are consistent in ID then...
Perhaps closer examination of the camshaft is called for, particularly the journals.
~~~~~~~~~~~~~~~
Twenty thousandths of an inch is close to .5mm (FIAT is metric). A novice machinist could easily mistake graduations and this calls into question the other measurements on the cam.
https://www.semasan.com/breaking-news-archives?utm_campaign=DrivingForce_DF272&utm_content=SeeAllLeg
Re: Reducing cam bore ID in an aluminum cam pulley?
Thanks for the suggestions. Yes, bore and sleeve would be the correct solution but would likely cost me $150 or so.
I think I will try the shim wrap on the cam. It is needed there to keep the pulley centered while I torque the cam bolt. Once tight I do not think it would move.
I think I will try the shim wrap on the cam. It is needed there to keep the pulley centered while I torque the cam bolt. Once tight I do not think it would move.
Re: Reducing cam bore ID in an aluminum cam pulley?
I have multiple cams and they all measure the same 29.95mm. The pulley is likely made in china for a US aftermarket company. Not sure why the ID is so big. The intake pulley from the same source runs absolutely true. Different batches? When you get stuff made in china, you never will know who/where it was actually made, unless you deal directly with the mfg.Kevin Johnson wrote: ↑Thu Sep 17, 2020 2:54 am The next Captain Obvious move to check both cams and sprockets ("pulley").
If the sprockets are consistent in ID then...
Perhaps closer examination of the camshaft is called for, particularly the journals.
~~~~~~~~~~~~~~~
Twenty thousandths of an inch is close to .5mm (FIAT is metric). A novice machinist could easily mistake graduations and this calls into question the other measurements on the cam.
Re: Reducing cam bore ID in an aluminum cam pulley?
good suggestions
also, how about tig the pulley ID and mill it to fit cam snout ?
also, how about tig the pulley ID and mill it to fit cam snout ?
Re: Reducing cam bore ID in an aluminum cam pulley?
What does the manufacturer say the hole size is supposed to be?
If it doesn’t match what you have(and is correct for proper fitment on to the cam) , will they replace it?
If it doesn’t match what you have(and is correct for proper fitment on to the cam) , will they replace it?
Somewhat handy with a die grinder.
Re: Reducing cam bore ID in an aluminum cam pulley?
The US vendor is sending me a new pulley. It is likely be just like the one I already have.
I got some aluminum foil tape ready to put on the cam. This is a 2-piece adjustable pulley. I find that there is about 0.015 radial play between the inner and the outer piece as well. This would affect concentricity of the outer wheel any time the cam timing is adjusted with belt tension on. I will need to shim this gap as well.
I got some aluminum foil tape ready to put on the cam. This is a 2-piece adjustable pulley. I find that there is about 0.015 radial play between the inner and the outer piece as well. This would affect concentricity of the outer wheel any time the cam timing is adjusted with belt tension on. I will need to shim this gap as well.
Re: Reducing cam bore ID in an aluminum cam pulley?
There's these guys for allowing bearings to be mounted in oversized, loose-tolerance housings. Take a look at their "AN" series. I don't know how you get just one, maybe ask for a sample or find a distributor?
http://www.usatolerancerings.com/index. ... g-download
PS "tape" seems like a really bad idea. You have the squishiness and sliding layers of the adhesive. I might look at K&S Brass shim stock from Ace Hardware.
Dave
Re: Reducing cam bore ID in an aluminum cam pulley?
Very interesting. Thanks.Nefario wrote: ↑Sat Sep 19, 2020 9:01 amThere's these guys for allowing bearings to be mounted in oversized, loose-tolerance housings. Take a look at their "AN" series. I don't know how you get just one, maybe ask for a sample or find a distributor?
http://www.usatolerancerings.com/index. ... g-download
PS "tape" seems like a really bad idea. You have the squishiness and sliding layers of the adhesive. I might look at K&S Brass shim stock from Ace Hardware.
I have the pulley back in the engine, all adjusted. Running true now. The shim is only needed until the cam bolt is tightened. After that, the bolt holds the pulley tight. I had to find a way to tighten the bolt w/o using leverage on the pulley to keep the cam from turning as that would have forced the pulley off center as far as allowed by the remaining gap. I locked the cam with two large wisegrips in the cambox and used an impact wrench to tighten the bolt w/o any force on the pulley.
Running good now and no more whining belt noise.
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Re: Reducing cam bore ID in an aluminum cam pulley?
Can the shim migrate backwards into the lip seal ?
10:47 here -
https://www.youtube.com/watch?v=cZbyHf0dwak
10:47 here -
https://www.youtube.com/watch?v=cZbyHf0dwak
Re: Reducing cam bore ID in an aluminum cam pulley?
A good question. I hope not. I do not think there is any movement there that would work the shim tape around.Dan Timberlake wrote: ↑Sun Sep 20, 2020 10:52 am Can the shim migrate backwards into the lip seal ?
10:47 here -
https://www.youtube.com/watch?v=cZbyHf0dwak
In the linked video, I do not like it that he has paint on the pulley where it mounts at the end of the cam and under the bolt washer. I would worry about the paint thinning and resulting in the bolt coming loose.