Tight 383 Cam Bearings

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Aaron.M

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I threw a Lunati cam into my 383 this evening and everything would spin ok until the cam went into the second half of the last bearing. Once it's all the way into the last hole, I need both hands to get it rotating. It then spins, but fairly tight. If I pull it out about 3/8", it spins relatively good. Will this break in or am I in trouble?
 
I would nervous, but certainly no expert!
 
Don't risk it. Bearing scraper on the tight one... some use an old cam with grooves cut (lengthwise) in the journals as a handy rotating knife.
 
If you pull the cam out you will see marks in the bearings where it is tight and rubbing. you need to scrap the bearing at that spot very lightly and try the cam again. keep doing this till the cam spins nice.
 
I had the same thing on the last 383 I did. Camshaft rotates at half-speed of the crankshaft. I ran it as is with no issues based on my machine shops recommendation.
 
On this one, tight ain't right! The oil holes should be lined up and the bearings must be installed perpendicular to the cam tunnel centerline. 65'
 
you need to check cam for straightness. put it in v-blocks on end journals, or between centers on a lathe and check for runout with a dial indicator.
If it is within a couple thousandths, then look to scrape bearings.
 
Do you have a big block cam core? If so, grind a diagonal slot in the cam bearing journal that is having trouble. Then, gently install it while turning. This will dress the cam bearing and remove a small amount of metal to allow it to free up. Blow all the metal shavings out assemble and rock on.
 
Before i scrape i check to see if it can be taped straight with an installer.
Like mentioned, look for the dark spot on the offending cam bearing and tap it in just a hair more on that side closest to you.
Just a hair.
 
If the cam was bent, would it be harder to spin through the rotation somewhere? Mine is consistently tight, doesnt get worse anywhere.
 
Aaron.M said:
If the cam was bent, would it be harder to spin through the rotation somewhere? Mine is consistently tight, doesnt get worse anywhere.
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not necessarily. It only takes a few minutes to check for runout, why would you not do that? I'd certainly do that before I started carving on new bearings.
 
Aaron.M said:
I'm not about to carve anything. I'm contemplating leaving it alone.
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If it is tight it will wipe the bearing out and maybe the cam and maybe the motor. This is a very common problem with early BB mopars engines, I would not chance it.
 
Aaron.M said:
I'm not about to carve anything. I'm contemplating leaving it alone.
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It's a very old accepted method. It's even in some service manuals. Suit yourself.
 
Aaron.M said:
I'm not questioning the method, I'm questioning my ability to pull it off haha. I'm going to pull it out and see if it's bent first.
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It's not. You more than likely have a camshaft bearing in just a little crooked. It's easy to do if you're not paying close attention when installing.
 
MOPAROFFICIAL said:
Before i scrape i check to see if it can be taped straight with an installer.
Like mentioned, look for the dark spot on the offending cam bearing and tap it in just a hair more on that side closest to you.
Just a hair.
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I've found this to be the case more than once. A little judicious tweaking with the installer could be the solution.
 
RustyRatRod said:
Do you have a big block cam core? If so, grind a diagonal slot in the cam bearing journal that is having trouble. Then, gently install it while turning. This will dress the cam bearing and remove a small amount of metal to allow it to free up. Blow all the metal shavings out assemble and rock on.
Click to expand...
Rusty hit the nail right on the head, Chrysler machined the front three cam journals first, the rear two were machined after from the rear so there can be some issues like you are experiencing this requires newly installed cam bearings to be "broached" like what Rusty explained in his post.
Rusty does indeed have knowledge most others do not.
 
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