splitpartsunlimited |
Wed Nov 06, 2024 1:07 pm |
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i have been offered a NOS -2 camshaft for my 58 engine , anybody knows what "-2" means ?
i think it is something related to the gear , but still not sure
thank you !
ricardo |
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KTPhil |
Wed Nov 06, 2024 1:39 pm |
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https://gowesty.com/blogs/article-library/cam-back...ivfK-2I3zU
Quote: During the engine-building assembly line process, the technician building the engine would simply grab a standard cam and place it in the engine block. If the backlash between the cam and crank gears was too much, he would grab a "plus" cam (+), and if it was too tight, he would grab a "minus" cam (-). This was an iterative process until the tech was able to get just the right backlash.
I remember reading about a process of fitting crank and cam in a block half, rotating and seeing if the cam gear "jumps". I can't find it (assuming I am not imaging this), and I also don't remember which direction you go in marking when it DOES jump. Maybe someone here has a better memory or a bookmark?
EDIT: It was something like this note from shoptalkforums:
Quote: Holding the crank stationary, try rocking the cam gear back and forth - you want no play. Try rotating the crank CCW (from pulley end), see if the cam "walks" out of the case. If it does, clean the gears and try again. Still tight? mix up a little valve grinding compound and oil and dribble this over the gears. Spin it over a good ten minutes by hand, clean everything spotless, test it again. Some do this on every install and even rig up power tools to do the turning which obviously cuts the time down considerably. If you can feel play right off the bat, then go hunting down gears.
Here is another note:
Quote: Backlash spec is 0.000-0.002"
Cam gears use to be available from -7 to +7 for gear pitch.
The number mean the difference of 1/100mm.
Example a +1 would be 1/100mm more pitch and -1 would be 1/100mm less pitch. |
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VW_Jimbo |
Wed Nov 06, 2024 11:29 pm |
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The camshafts came in 7 different sizes from the factory, if memory serves me. Seems like it was -3, -2, -1, 0, 1, 2, 3. It was for the freeplay between the cam gear and the crank gear. You checked it with a dial gauge, but many mechanics used the cam grab check, by turning the crank. If the camshaft jumped out of its place during a rotation of the crank, the freeplay was too tight. Or if the sound was off, guys could tell.
I use the feeling test, by rotating the camshaft back and forth while listening to the resonation between the gears. The right freeplay has a tone to it, that is unmistakably. But there are all kinds of ways. And yes, the cam will walk right out of the case if the gears are too tight! There was a mechanic I worked next to, Ed Duffy, who used that method. He built thousands of long locks and none of them came back from his work! |
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oldslow |
Fri Nov 08, 2024 7:21 am |
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FYI BBT now has the whole range (-2 to +2) 36hp cam gears. |
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bnam |
Fri Nov 08, 2024 8:16 am |
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Cases were marked/stamped Wx indicating the cam tolerance needed. Wx ranged from W7 to W0 to WG. W7 indicates a +7, while WG indicates a -7 cam.
This was for the 40 hp and on engines. Not sure if same applied to the 36hp. |
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