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Rotational friction question |
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Amc wannabe
AMC Apprentice Joined: Jan/08/2014 Location: DE Status: Offline Points: 86 |
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Posted: Jul/14/2019 at 6:43pm |
anybody know what a good beam torque wrench indication would be for spinning the rotating assembly? I know The rotating assembly spins free with no snags but it does take a bit of force. Could the assembly lube I used be increasing the resistance I’m feeling? Also with assembly lube should I still be able to spin the cam easily by hand without leverage?
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Boris Badanov
AMC Addicted Joined: Dec/14/2013 Location: NH USA Status: Online Points: 4209 |
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A lubricated cam with no lifters should turn freely.
So should a lubed crank with no rods. When you start adding things like the timing chain and on and on the friction will add up. |
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Gremlin Dreams
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Amc wannabe
AMC Apprentice Joined: Jan/08/2014 Location: DE Status: Offline Points: 86 |
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ok, the rotating assembly gradually got more friction as I added princes. Turned pretty easy to start. I am concern about the cam though. It doesn’t want to spin unless I use the cam gear as my point of leverage. I tried to just grasp the shaft and the key and it’s hard to get going. I thought I heard assembly lube adds resistance compared to normal oil but thought it might be one of those old wives tales that people could clear up for me here.
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ChillyB
AMC Nut Joined: Nov/14/2018 Location: PA Status: Offline Points: 371 |
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Maybe there is a ding on the cam bearing edge from installation, or cam install. I read one poster here once state the oil drillings to the cam bearing bores may have raised craters from dull tooling, which will form a pinch point in the bearing bore. No experience. Mine spun freely.
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Boris Badanov
AMC Addicted Joined: Dec/14/2013 Location: NH USA Status: Online Points: 4209 |
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Cam must be free in the bores.
If it is not you risk spinning a cam bearing. If the motor is a new build you can either scrape the offending cam bearing(s) or have the cam bearings polished .001 smaller and try again. Neither is the stuff of back yard mechanics. My guess is that it is best to polish the cam journals. |
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Gremlin Dreams
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MattsGarage
AMC Apprentice Joined: Jan/24/2019 Location: El Paso TX Status: Offline Points: 95 |
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I would say even with assembly lube the cam should turn by hand. Did you install the bearings? My machinist has to have the cam with the block to ensure nothing binds up after bearings are installed, and there's almost always a bind somewhere. He lubes it up and makes sure it turns by hand from the shaft on the end of the cam.
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Amc wannabe
AMC Apprentice Joined: Jan/08/2014 Location: DE Status: Offline Points: 86 |
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my machinist who has built quite a few AMCs put them in and said they put a test cam in and it spun freely. I’m really hoping it isn’t due to the raised passages like was mentioned, I have no way to smooth those myself unless there are techniques I don’t know yet
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Boris Badanov
AMC Addicted Joined: Dec/14/2013 Location: NH USA Status: Online Points: 4209 |
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Did you nick or bruise a bearing putting the cam in the block?
Cam bearings are very soft. |
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Gremlin Dreams
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Amc wannabe
AMC Apprentice Joined: Jan/08/2014 Location: DE Status: Offline Points: 86 |
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I was really gentle in my personal opinion, but when I check 2moro I will verify it. Cant say I haven’t been my own worst enemy before
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MattsGarage
AMC Apprentice Joined: Jan/24/2019 Location: El Paso TX Status: Offline Points: 95 |
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When I take mine in they always want the cam I'm going to be running. Maybe different tolerances from different manufacturers of cams? I'm not sure. But even on different makes of engines he wants the exact one I'll be using. He says older mopars and amc are generally the ones need fitting.
Just to add, the reason my guy probably wants the cam I'm actually running is probably because he polishes the journals on the cam instead of scraping the bearings, like I've had others do. I just take the cam when I pick up the block and it takes him about 10 minutes to make it right. Edited by MattsGarage - Jul/14/2019 at 8:59pm |
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