How free should cam spin?
Thread Starter
Joined: Jun 2014
Posts: 1,241
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From: Noblesville, IN
How free should cam spin? Just got my cam installed. How freely should it spin? It doesn't feel like it's hitting anything, but it takes some effort to spin. Not sure if something is too tight or its just the assembly lube.
Last edited by HappySalesman; Jun 21, 2017 at 07:41 PM.
Thread Starter
Joined: Jun 2014
Posts: 1,241
Likes: 47
From: Noblesville, IN
I did check clearances. I don't remember them off the top of my head but I they were within spec...
The old cam spun very easily, but that was a stock cam with 170k on it. It's since had new bearings installed.
I can spin the cam by hand, it doesn't feel like anything is binding necessarily, just takes some effort (more effort than the crank did). I'll pull the cam and see if there are any wear marks on it or the bearings.
The old cam spun very easily, but that was a stock cam with 170k on it. It's since had new bearings installed.
I can spin the cam by hand, it doesn't feel like anything is binding necessarily, just takes some effort (more effort than the crank did). I'll pull the cam and see if there are any wear marks on it or the bearings.
There's a special tool that looks like a potato peeler and is used to chamfer the edges of the cam bearings because the driver/installer tool can mushroom the side of the bearing shell while installing. Oil in the bore housing and on the back of the bearing shell can help minimize this.
Lastly if the shop that did your block machine work didn't acid dip it (and very few do anymore) then they most likely baked and tumbled it. The shot blasting procedure causes machined edges to flatten or mushroom (main bores, lifter bores, and you guessed it CAM bores)
Mains typically get a quick line hone, lifter bores get dressed with a small brake cylinder hone but few shops will hone the cam tunnel. So when the new bearings get installed there is undue pressure or pinching which when combined with a brand new cam will cause it to turn tighter than it should. Will it be OK?? Perhaps but IMO it should be super easy and basically done RIGHT !!!!!
Lastly if the shop that did your block machine work didn't acid dip it (and very few do anymore) then they most likely baked and tumbled it. The shot blasting procedure causes machined edges to flatten or mushroom (main bores, lifter bores, and you guessed it CAM bores)
Mains typically get a quick line hone, lifter bores get dressed with a small brake cylinder hone but few shops will hone the cam tunnel. So when the new bearings get installed there is undue pressure or pinching which when combined with a brand new cam will cause it to turn tighter than it should. Will it be OK?? Perhaps but IMO it should be super easy and basically done RIGHT !!!!!
Thread Starter
Joined: Jun 2014
Posts: 1,241
Likes: 47
From: Noblesville, IN
Pulled the cam and double checked the clearances. They're a little on the tighter side (.0025 at the tightest, .0029 at the loosest) but I don't think that's the problem.
To be honest I think it's just the assembly lube. It doesn't feel like I'm fighting a mechanical issue, it just feels sticky lol.
To be honest I think it's just the assembly lube. It doesn't feel like I'm fighting a mechanical issue, it just feels sticky lol.
^ was gonna ask what type of lube, if any, did you use. if none, that is an issue! I've always used just motor oil and it spun freely so I cannot comment on the assembly lube but I imagine the oil viscosity is way thicker.
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TECH Addict
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That is plenty of clearance, if the machine shop didn't hone the cam bearings to size you will feel some drag as you turn it. Once you get a load on the cam small differences between the bearing surfaces will smooth out. Even if the very edges are pushed a little, As long as you have proper clearance reading I wouldn't worry about it.
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Sure. If the box got dropped onto a concrete floor, it is possible to bend it the slightest amount, or if something heavy fell on it somewhere. All wild guesses, but possibilities. Anywhere in the shipping cycle something could happen. Rare, but still happen
Try oil first.. Some of those assembly lubes are really "sticky". I hate to use them on bearings for that very reason. If something is actually just lightly binding, you won't feel it when turning the engine over.
Thread Starter
Joined: Jun 2014
Posts: 1,241
Likes: 47
From: Noblesville, IN
Alright, I'll try some regular oil.
BTW, how do you guys measure the rear-most bearings with the crank/rods in the motor? I had the foresight to measure them before I installed anything, but with the way my stand is set up i can't get my gauge in there to measure if cranking the mains down made any changes.
BTW, how do you guys measure the rear-most bearings with the crank/rods in the motor? I had the foresight to measure them before I installed anything, but with the way my stand is set up i can't get my gauge in there to measure if cranking the mains down made any changes.
Last edited by HappySalesman; Jun 23, 2017 at 12:27 AM.
Alright, I'll try some regular oil.
BTW, how do you guys measure the rear-most bearings with the crank/rods in the motor? I had the foresight to measure them before I installed anything, but with the way my stand is set up i can't get my gauge in there to measure if cranking the mains down made any changes.
BTW, how do you guys measure the rear-most bearings with the crank/rods in the motor? I had the foresight to measure them before I installed anything, but with the way my stand is set up i can't get my gauge in there to measure if cranking the mains down made any changes.
