Anyone ever try installing new cam bearings without removing the crank?

I've got a short block on the stand, and I'm swapping cams and noticed that the front bearing was pretty scratched up. Assuming they all are.

-- Joe

 

I haven't... heh. As long as the counter weights arnt in the way i don't know why it couldn't be done..... right?

 

Yes, i used a large cotter pin in the journal oil hole to roll the top brg out and the new brg shell in. U can trim the cotter pin legs to fit as needed - the legs will sqaure up to the edge of the shell and will clear the block saddle - u may have to flatten the legs a bit. Just slowly turn the crank by hand enough to get the top shell out.

I had some scratches on the crank to so u used a strip of 400grit sand paper to polish it some. The Chevy Power Catalog 6th edition does this. But i used some finer 600grit after that. Yea the sandpaper polish by hand was standard treatment at that time. The CPC has pix showing how to do this. Hey man its a sbc.

 

Hrmm.. You had the rods out huh? I was not planning on removing the piston+rods..

Maybe I'll just change the front bearing and pretend the rest are fine..

-- Joe

 

It's already on the stand.....& you want to just do the front bearing?
LOL, man.... it's really not that much more work to finish tearing it down & do it right. It'll be a HELL OF A LOT MORE WORK LATER... if your assumptions are wrong.
Good luck

 

Ooops! I thought he said the front crank brg, not the cam brg. Well I'll leave that up there for anyone wanting to roll out a crank brg.
Too much caffeine I guess.

 

LOL! I can relate! Long days & longer nights!

 

it takes, what, 20 minutes to pop the rotating assembly out of a block and open everything up?

 

Here is why.

I remove the rods, and then I look at say "man do these big ends look out of round?".

I remove the crank and I'm like "Man, these journals look like they need to be polished".

So next thing I know I'm sending the crank and rods out. I measure the bore and find that it's worn to about 4.005-4.008, so I'm like "man, I should have this bored .030 over".

Next thing I know I'm $700 deep into machine work and new pistons for a motor that I'm just doing a cam + head swap on so I can stick it in my boat.


Not to mention I still have a 355 at the machine shop for my vette that I've been waiting for 2 months on.

-- Joe

 

Sounds like the bearing probably aint that bad.........

If it looks rough, pop the front one out/in. Then stick the cam in and button it up.

 

It's just really scratched on the bottom. I'll replace that front one, and bolt it back up.

-- Joe

 

I hear ya, just know my luck & I'd end up with a seized cam that's broken in 3 places & takes out a couple of rods along the way. LOL
But, not everyone has my kinda luck. ..so good luck

 

A scratch will just hold oil. If its with in specs, just make sure there is no bur, maybe look at the cam too. Is that how it got a scratch??

 

Ohhhhh, I don't know bout that....

Me: Hey install these new Motor Mounts
Him: You got it
Me: Here's a Tranny Mount while were there
Him: You bet
Me: Hey, take that TC Cover over and check the TC Mount bolts...It'll only take a second
Him: I can do that
Me: Were they tight?
Him: Yeah, they were tight, but you need a new Flex Plate; cracked all to hell
Me: %$#@ !!!!!

Bank Account: $500 LESS!

So yeah, we all have that luck at one time or another!

 

It's a roller block that had a flat tappet cam in it. Was in a '88 blazer.

We fired it up and let it run to make sure it was good. then yanked it out.

I'm tearing it down to put the L31 heads on it, marine roller cam, etc.

When I was pulling the cam out it got 'stuck' after about 6" out. I tapped it back in, and then pulled it back out, rotating as I pulled it out.

Once out I looked at the front bearing and it's all scratched up at the bottom. You can feel it with a naked finger.

I don't know if it's related to the cam, or just wear from being an older motor.

I'm gonna try and post a picture later. I don't have cam bearings in the shop anyway so it's on the stand with a bag on it.

My shop is kind of a disaster right now, I've got the firebird on the lift, a boat motor on the stand, and another motor for the vette, heads and oil pans everywhere, etc.. I need a bigger building


Anyway, like I said earlier it's just a used short block going in my baja. I don't really wanna put too much money into it cuz the boat isn't really worth much. As it is I hate wasting vortec heads on the thing.

-- Joe

 

DO you have a dial bore gauge? Id just make sure its smooth and in spec and run it. Ive seen some pretty knarly looking cam bearings and she was running fine before tear down.

 

Yep. What's the spec range ?

-- Joe

 

Does it catch your nail, or just feel rough ( lite scratches ), should have at least a couple thou for oil clearance over the physical diameter of the cam. That roller will be different than flat tappet.
I've known guys that had gouges in them & take a knife or file a trim it down. ... but those were for crash derbies, so it didn't matter.

 

This is a article from hotrod.

When fitting aluminum cam bearings, it's important to allow sufficient bearing-to-camshaft clearance, since the harder aluminum alloy bearings won't wear in as rapidly as babbitt bearings to make their own clearance. Minimum clearance should be 0.002 inch for stock engines and 0.003-0.004 inch for high-performance engines.


What year block again? I will look in my federal bearing book for exact.

 

The old rule of thumb is to provide .0007? to .001? of bearing clearance for every inch of shaft diameter in a stock engine. Consequently, if the crankshaft has two-inch diameter journals, the rod and main bearings should be assembled with about .0015? to .002? of clearance.

Good read here. Sounds like it depends on what oil type you run.

http://www.enginebuildermag.com/2013...ng-clearances/

-Dan.

Still looking in my fed book for ya.

 

More good reading.

According to a Clevite technical bulletin, the typical production engine recommendation is between 0.00075 and 0.0010 inch of bearing clearance for each 1.00-inch journal diameter. So for a small-journal small-block Chevy connecting rod of 2.00 inches, that would mean a bearing clearance of between 0.0015 and 0.002 inch. Most performance engine bearing recommendations tend to avoid clearances below 0.002 inch, even for small-journal diameters. Clearances on the tight side will increase bearing load capacity, but this also drastically reduces oil flow, which increases bearing temperature. That's why a slightly wider clearance is acceptable while sacrificing minimal load capacity.

http://www.hotrod.com/how-to/engine/...ing-clearance/

I know this says crankshaft but im pretty sure the cam applys too. Any bearing surface.....

 

So my "couple of thou " over the physical diameter of the cam, would put you in the ball park

 

Yes it can be done.

Hardest part will be getting the old ones out: usually you have to knock them inwards, remove the tool, and crush the bearing.

Putting in the new ones is no different with the bottom end in than with it out except it being a pain in the drain to operate the tightening function of the tool.

 

The tool I have doesn't have the rubber tightening mechanism. It's just a pole with a round thing on the end to grab the bearing. So you have to remove them and install the min reverse orders.

I have not done it in about 10 years, so my memory might be a little rusty but. Normally the machine shop does cam bearings before I even get the block.

-- Joe

 

Right, you'd always do them in reverse order; at least, 3 from one end then 2 from the other.

If memory serves, there are 3 part #s of bearing in the set: 3 & 4 are the same, and have the smallest OD; 2 & 5 are the same with a larger OD; and then 1 is different from the others with the largest OD. So you can knock out 1 (and crush & extract it), then 2, then 3, from the front, then install them 3, 2, 1; then from the rear, remove the plug, 5 & 4, and install 4 & 5 and the plug. If you make a good stout pulling tool (maybe a piece of strip stock or rod stock with a hook bent onto the end) you can probably yank em back out and let the journals crush em a bit, without having to do that as a separate step.

 

Remember... Be sure to use the correct diameter cam bearing for each of the journal diameters, cause SBC have 3 different journal sizes. #5- 2.010 #4- 2.000 #3- 2.000 #2- 2.010 and #1- 2.020.

Here, this is how I do mine.

https://www.proformparts.com/common/...aring_tool.pdf

 

This is a good read too.

Whoops, edit-

http://www.dura-bondbearing.com/Port...20Bulletin.pdf

 

Hey Guys,

So that block I ended up putting a bag over it and moving it to the corner. There is just soo much sludge in the oiling system that I think I'd rather hot tank it, and being a 2 bolt main roller motor it would be a great candidate for a splayed cap 355.

So anyway, I picked up another motor for this project. This is a running L03.

I stripped it down to a long block, removed the factory cam. I was going to just toss the marine cam in, and bolt it back up until I looked at the cam bearings. Pictures attached.

It seems like I just can't win. If I do a full rebuild I'm going to be way upside down on this project.

The block is pretty clean. I looked at each cylinder with my camera and the hone still looks ok and a very minimal ridge. No damage. I'll do valve seals and springs.

-- Joe

 

IMO, I would pick up a cheap rebuild kit ( like p.a.w. or ebay, soft kit bearings, seals, gaskets ) $150+/- a few bucks . Really, you're only about an hour away from having it completely torn down. And it's not hard to replace the bearings.
Sorry, you're having a bad run.... but ,it could be worse. ... the block could be cracked

 

You know what they say about BOAT. Bust out another thousand.

This kit is labeled 93+ rather than 88+ but it should work:

http://www.ebay.com/itm/93-95-Chevy-...4jzH4Q&vxp=mtr

Just do a quick re-hone.

-- Joe

 

$90.00, a little time, clean it up & paint it.... go have fun
You know how it goes Joe, just another rodeo.

 

Yup. I guess I'll tear it down tonight and knock the bearings out.

I guess I've got two more months until it's warm enough to use the boat anyway.

-- Joe

 

LOL, that's the spirit!
That's where a lot of guy's go wrong IMO, instead of going the extra 2 steps.... they just throw in the towel or throw it together anyways, then get mad as hell when MURPHY jumps up & bites them in the ***.

 

Murphy was an optimist.

 

LMAO!

 

Took it apart. Cam bearings were junk. Rod and main bearings looked ok. Dirty, but ok. Had oil down below.

Heads were stuck on. I suspect it over heated a few times.

Stripped the block down and cleaned it. Just gotta MIC the journals on the crank and order a kit.

-- Joe

 

Doesn't look too bad, you'll know for sure when it's torn down & cleaned.

 

Journals were 2.45 and 2.10, so I ordered the rebuild kit.

I'm a little nervous about the heads. They are full of powder. Someone must have used dexcool. That and the gasket is like melted to the heads.

-- Joe

 

Tear them down, clean and inspect, new valve seals, check springs & seats. You have a mandrel & stone bit to kiss the seats?

 

Yeah, I'm just concerned that the decks might be warped. I might kiss them on the mill as well. We shall see.

-- Joe

 

Wouldn't hurt, level them up and run a 0 pass. It just makes sense if you have the equipment, or access to the equipment. ... it won't take long & that's 1 less thing to worry about.