wiped out cam bearing

[john a]

Hi all, I,ve been lurking here for a number of years but have never posted. Now its time, I was going to do cam change on my 444 and  discover the bottoms of all the cam bearing are wiped out! This motor has maybe 4000 miles on it. The cam was a comp 270 H with the valve springs that came with the Edelbrock heads. If I remember right the springs are 130-380lbs.  Any ideas what would cause this?

Thanks in advance

John

[Joe-JDC]

Were cam bearings changed at rebuild?  If so, were they clocked correctly--oil holes aligned properly?  Was the camshaft lubed before install, was engine pre-oiled with pressure throughout system before initial start?  Did the engine start immediately, or did you have a hard time starting it the first couple of times?  Did you run it above 1500rpm for at least 20 minutes on initial startup?  These are just a few things that could cause the problem.  Joe-JDC

[john a]

Thanks for the reply. The answer to your questions is yes to all except start up, I did have to shut it down after 10 minutes for about 10 minutes and then continued on for 20 more. One thing that has bothered me about the valve train is the angle of the push rod to the rocker arm when the valve is closed. I have adjustable rockers with about 4 threads showing below the rocker. Do you think the poor geometry could be the problem?

[ScotiaFE]

Any chance of a picture of the bearing.
You really don't have enough cam or spring to push that hard on the bearing.
Possible dirt in the gallery's?

[jayb]

Thanks for the reply. The answer to your questions is yes to all except start up, I did have to shut it down after 10 minutes for about 10 minutes and then continued on for 20 more. One thing that has bothered me about the valve train is the angle of the push rod to the rocker arm when the valve is closed. I have adjustable rockers with about 4 threads showing below the rocker. Do you think the poor geometry could be the problem?

Poor geometry is not going to cause that problem.  Your springs are also not heavy enough to be an issue.  I wonder if perhaps you got a bad set of cam bearings, or for some reason they are not getting oil?

[john a]

I will try and post pics when i get the bearings out. This explaines why the oil pressure was lower than normal. I should mention the rod and main bearing looked perfect. Maybe I did get a bad set of bearings.
This motor is going into a different car so I thought a little sportier cam was in order. What do you guys think of the comp 280 flat solid? Its going into a 63 Futura, 444, 10.1, stock Edelbrock heads, RPM intake, 850 Holly, 350 gear.

[Barry_R]

Cant think of many things that would cause that in a mild build.  With the annular groove behind the bearings in 390 and 428 blocks oiling should not be a problem and the clocking is not that big of a deal in such a mild combination.  Possible bad bearing alignment in the installation that was allowed to "wear in".

[jayb]

I will try and post pics when i get the bearings out. This explaines why the oil pressure was lower than normal. I should mention the rod and main bearing looked perfect. Maybe I did get a bad set of bearings.
This motor is going into a different car so I thought a little sportier cam was in order. What do you guys think of the comp 280 flat solid? Its going into a 63 Futura, 444, 10.1, stock Edelbrock heads, RPM intake, 850 Holly, 350 gear.

Do you mean the Comp 282S solid cam?  That is actually a very good cam for a street application; lots of low end torque, nice lope at idle, etc.

I think Barry may be onto something regarding the cam bearings.  If for some reason the cam bearing bores are out of alignment by a few thousandths, the cam would try to wear them straight.  This could have caused your problem.  If you put new cam bearings in the block, and then install the cam and it is tight, not rotating real easily, I'd say that could be your problem.  I had that happen once on a block that was welded to fix a crack; the welding pulled one of the cam journals out of alignment with the rest, and when the cam was installed it would barely turn.  I'd check for that before you put too much money into that block; have a new set of cam bearings installed, then install the cam and make sure it turns freely.

[fe66comet]

 Would change them out for some King berings with an oil groove. Also the race bearing is harder and more durable. I agree that the quality of the Bering would seem the culprit. If the mains did not spin or smear I would say run a brush through the galleys and blow them out with air. While you are at it tap them out with a 1/8 inch pipe plug on the ends for extra insurance if you haven't done that already. Kinda strange, wiped cam bearing I have never had, mains yes cam no.

Also would not hurt to buy a strait edge and feeler gauge set, check the cam also to see if the cam was not ground concentric with a bow in it, I actually have seen that a couple times.

[66FAIRLANE]

Interestingly the last time I tore down my 390 it was the same. I had to knock the cam out with a drift. All the bottoms were worn considerably. Mains and rods were fine. When I rebuilt it I used Clevite (not sure what was put in at previous build & cant remember what I knocked out) and stood the block vertically to see if the cam would just drop in under its own weight. It did and spun freely.

Still not real sure what caused it. Oil holes were at the bottom, maybe not the best spot but should have been ok. I finally put it down to valve bounce hammering. All my valves had little troughs in them from the rocker tips. This was standard Edelbrock out of the box heads with a 240, 245, 590 solid. I do like rpm though and it always got hammered. I just put it down to pounding. Will be interesting to see what they look like next freshen up.

I have changed out the valve springs as some of the original Ebocks were down to 90lb's.

[Barry_R]

Roughly 90% of the cam bearings in the US are made by Durabond.  I thought it was 100% but somebody corrected me and noted that the ACL bearings are made in Australia and they do their own...

[fe66comet]

If you buy a good quality bearing it should last a long time, I buy race bearings for their harder shell material but surface material is still not too soft to cause galling or smearing.

[john a]

OK so I got the new cam bearings installed along with the cam and it rotates smoothly. The new bearings have a harder surface than the old ones. I,m going to just chalk this up to bad bearings, I see no other reason for this to happen. When I degreed the cam it came in at 104.5, Comp recomends 106. This is with a used timing chain. Does anybody have any experience or thoughts about running it at 104? Its a com 282 S.

[My427stang]

104.5 is close enough to 106 in my book, assuming you have intake valve clearance (which I wouldn't expect to be an issue with only 1.5 degrees difference)

FWIW, I run my Bullet 282S copy in my 445 on 104, it pulls hard right from the bottom and seems to run strong up top.  However I also have some decent flowing heads

[blykins]

The timing set slack will probably retard the cam timing a bit, but even if it didn't, I'm a fan of early cam timing.