Yes, I would run a cam bearing like that. Peck marks will not matter, just broader wear or damage. If it does not spin freely, though, you need to remove some bearing material, probably from the rear bearing. I had one rear bearing spin in the bore once and cover the oil feel hole. I have had a couple more cams be sticky when turning and never ran them til I "fit" them by sanding. This is relatively common practice if the cam is tight. I have removed some bearing material (rear brng) with crocus cloth by hand until the cam could rotate freely by hand with the cam gear only (3" torque arm).

Lou

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Home of Slant6-powered fun machines since 1988

If it turns out to be dry valve guides, try oiling the stem from the chamber side of the valve.

Not dry valve guides. Took an idea from a diy valve spring compressor I found on a past thread - I welded a lever to an extra rocker and slid it over a shaft. I was able to “activate” every valve from opening to spring bind and they were super quiet

Watched a YouTube vid of a guy putting in cam bearings. He did one at a time and test fit the cam between each one so it would be easy to id which bearing(s) needed sanding

Ok, so ugly looking bearings will still work. But yea the cams way too tight - it wouldn’t turn by hand or with a 3” lever. Tight cam + spring pressure = squeak?

Ok… got old bearings out. Put rearmost new one in… and am having trouble getting it to turn easy from the get go. You can see the high spots become shiny as the cams forced to turn. Remove, sand with 2000 wet/dry with oil, clean, test, repeat. After 4-5 cycles it just keeps happening. Put in next bearing to hold the cam in case it was being caused by the weight of the cam causing it to not turn square - same thing.

I can keep going with the sanding but it’s going to take an extraordinarily long time. I’m thinking about making a scraper from the stock cam.

If the same thing is happening with a second set of bearings I’m thinking the journals in the block may be a hair off. Or… can cams bend?

What cam are you using? Is it brand new or reground, or?

Lou

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Home of Slant6-powered fun machines since 1988

I was told this was a fairly common thing that happened by an old timer engine builder. I did not know it happened at all until it happened to my sons engine. I had to take the block back to his shop and he actually had a tool that was made to shave a few thousands off the bearing. It did not look good when he was done but it was installed and ran for 50,000 miles without any issues.

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12.70 @ 104.6

I believe it’s new - ordered from erson directly. End is stamped with a 2015 date. Come to think of it even with just the one rear bearing it wasn’t a smooth insertion so unless the journal is oversize, probably not the cam

I know ideally after sanding or scraping your supposed to rip it all apart and clean but ugh what a pain. I wonder if I can just pressurize the main oil galley with air or solvent….


I’m kinda glad I forced myself to stop and address the noise concern. If I hadn’t I wouldn’t have seen that the rear journal oil holes weren’t drilled right until it was too late

Yep, always good to be careful. Good luck with rest of the fitting and assembly.

Lou

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Home of Slant6-powered fun machines since 1988

I've built 2 Slant Sixes and both were warped enough that the cam would not turn freely. Apparently, it's common to 'hand scrape' the bearings for clearance. That idea doesn't give me confidence.

Instead, I made a tool out of an old stock camshaft. I cut a groove in each bearing journal to serve as a cutting edge and with some cutting oil and a hand drill I spun the cam until it turned freely. The grooves are cut at an angle and offset a little so that they bite in just a little bit. This worked great and the bearings looked very nice after I was done.

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The local machine shop that used to be here always wanted a cam along with any engine they had to put bearings in, I know the "block guy" always had a bearing knife for that situation. One of the many 318s/360s I did thru them, they asked what I was using for a cam, I told them I had a new one, they asked me for my old one to use for fitment on future small block mopars they rebuilt as a "dummy" to have on hand to fit their cams when they did bearing installs

That was an adventure. Ok... I removed all the old bearings. I installed two new ones in #3 and #4 - sanded by hand - still tight. Installed #2 and #1, then modded an old stock cam similar to Procycles - cut two diagonal lines along each journal on opposite sides. Cut down the burrs with 2000grit.

Inserted in the engine lubed up... very difficult to turn, more so then the new cam was with the bearings that were previously in the block. A makita 20v 1/4" impact and 1/2" 20v rigid drill would not turn it. Moved it by hand some more with a wrench... tried the drill again... got it to go a few times but was very labored (and heard that same squeak I did originally....so yes, cam bearings can squeak!)

Took the scraping cam out expecting the worst. Did a good job on #2, 3, 4... but destroyed #1. Two large opposing gashes... probably from the initial turn. Looks like #1 was the tightest. Took #1 out. The original #1, although bad looking, cleaned up with a maroon scrub pad. Cleaned up 2-3-4 with the same (now worn) maroon pad. Put original #1 in - OMG cam turns reasonably well! Not one finger super smooth but much better. I was about to call it quits and walk away with a victory when I realized I put #1 in a hair too far... so I took it back out and reinserted.

Now cam won't go in #1 at all. Keep in mind this is the third time #1 went in. Discovered that it's a no-no to re-insert a cam bearing that's already been inserted once. Time to get another set of cam bearings just for #1. I'll make sure it slides on the cam before I put it in the motor. I'll install #1, then test fit the cam in backwards. I'll keep using the maroon pad until cam goes in backwards, then should be good... or at least good enough to run the scraper again

Y'all with experience are probably laughing if you've made it this far.... Learning the hard way... kinda sorta fun. bit costly. Procycle I read your other thread. Maybe my #1 is like your #4 but worse...

Just a FYI. Many years ago, I had a shop clean and install new cam bearings in a 440 engine. When I started installing the cam, it would not go in all the way. Rear cam bearing was too tight. Took the block back to the shop, where they installed a new bearing, and had the same problem. The shop found that the cam bore in the block was slightly small, and would "squeeze" the bearing. They did some investigating, and found that Chrysler had some big blocks that had the wrong size rear cam bore, and used a special cam bearing to correct the problem, at factory assembly. My shop cured the problem by correcting the cam bearing bore in the block, so a standard bearing could be used.

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Charrlie_S
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Don’t think there are any special slant cam bearings are there? Unless there’s a crossover to the v8 world

So… how are you supposed to properly clean the block that now has fitted cam bearings? You can’t take the bearings out and put them back in. The oil hole in the block is more of a slot in #1,2,3…. Pressurizing the galley manually will only force any crud deeper into the unexposed area of the slot


Is there a spec for cam bore in the block? I saw one of Doc’s post say for #4 it’s 2.080-2.081. Wasn’t sure if the rest were the same. Only bearing id spec is in the manual.