Author Topic: Reprofiled camshaft?  (Read 571 times)

Online Greybeard

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Reprofiled camshaft?
« on: 26.05. 2015 18:47 »
I've asked this question before but not had a response so I'll try again:

When I rebuilt my engine I used a reprofiled camshaft: ie an old camshaft that had been ground to correct standard profile into the existing metal and then rehardened. Have you any experience or comments on using a similarly reprofiled camshaft?
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Online muskrat

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Re: Reprofiled camshaft?
« Reply #1 on: 26.05. 2015 20:44 »
G'day GB.
I haven't had one myself. The only problem I can see is if too much is taken off the followers might not drop far enough to follow the base circle of the cam. This can mean the followers will miss the ramp and lift with a bit more shock. That could strain the rest of the valve train (old weak pushrods for example). I had this problem when I used a 1.5mm compression plate under the barrels.
In saying all that a lot would have to be removed from the shaft to cause that. In the region of 1mm from the base circle.
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'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
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Re: Reprofiled camshaft?
« Reply #2 on: 26.05. 2015 21:14 »
Thanks Musky,
Some things to think about there.
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Offline duTch

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Re: Reprofiled camshaft?
« Reply #3 on: 26.05. 2015 22:07 »
 
    Must've missed that G.B.- I had mine done by a local guy Ivan Tighe, but a long time ago ....his sons now run the show.
 I've also been wondering the same thing as what Musky suggested, and I've seen mentioned before...

 
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if too much is taken off the followers might not drop far enough to follow the base circle of the cam.
...which is where I was going in my post to Bills thread:
              Re: Rocker Tappet adjustment

 
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a tad and away from the valve by a similar tad, so two tads worth

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  ...two tads'd be a tur ...?..um  actually that could be deceptive, but when I was trying to determine if I needed longer pushrods, I measured the rocker arms (well tried in a rudimentary fashion), and came up with one arm on each being longer than the other by as far as I can gather from my 'jottings' about 1/4", but forget which way...no great surprise, but I ended up taking what I could get anyway...

 Point is, taking the lever/ratio into account; one tad would be a tad bigger than the other tad, so dere's a tird tad.... *????*
Modify message

  Should be able to check with a dial gauge, by putting the gauge on the rocker arm valve fully closed (zero lash) and turn the crank and note at what degrees the valve starts to open & fully close....
  (I can't remember if I did it or not)
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Re: Reprofiled camshaft?
« Reply #4 on: 26.05. 2015 22:45 »
Thanks Dutch.
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Online muskrat

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Re: Reprofiled camshaft?
« Reply #5 on: 27.05. 2015 10:02 »
I'll have to look it up but I think the tappets are set at 0.015" to take a reading of the profile.
Cheers
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Re: Reprofiled camshaft?
« Reply #6 on: 28.05. 2015 12:22 »
...The only problem I can see is if too much is taken off the followers might not drop far enough to follow the base circle of the cam. This can mean the followers will miss the ramp and lift with a bit more shock. That could strain the rest of the valve train (old weak pushrods for example)...

Musky,
Thanks for that thought; it hadn't occurred to me.
This morning I slowly turned the engine over while I rested my finger on a pushrod. There doesn't appear to be any slack as the cam rotates ie. the pushrod dips and then lifts straight away so I feel that the cam followers are in contact with the camshaft all the way around.  *smile*
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