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While leaving RPM out of the equation, Does the likelihood of a spun bearing increase as cam size increases?

For example, Installing a hotcam and revving to 6500 vs installing a cc306 and revving to 6500. Am i more prone to failure with the cc306?


Thanks

 

Cam bearing longevity and spring pressures are directly related. Changing to a more aggressive profile, all other components remaining the same, usually involves upping the spring pressure. Did you change the springs out for this swap?

Could also be that you damaged a bearing while installing the new cam.

-Mindgame

 

Also though, the cam spins at half the speed of the crank.

I figured mine would be cam after spinning a bearing only @ 6k miles after my cam swap. Got it apart and it was 7&8 rod bearings. Looks like oil system failure or I sucked it dry.

 

Actually i haven't done anything yet. I plan to go with LE2 heads & LE1 cam setup. I'm debating whether or not i should go with a bigger cam though. If bigger cam = greater chance of killing bearings, then i probably would want to stick with the LE1 cam instead of the LE2 cam.

 

Would replacing the cam bearings when doing a cam install and going with a higher pressure (not volume) oil pump help to prevent spinning a bearing in a higher mileage engine?

 

If everything is set up right (a LE package will have the right parts) then you have minimized your chances. Your just as likely with the le2 to spin one as the le1 in my view.

 

Making sure everything is CLEAN is going to be the most insurance.

You spin cam bearings because they are the ones that catch the dirt first out of all the bearings.

Bret

 

Is it safe to blow compressed air into the cam hole to blow out any dubree before installation of the new cam?

 

sabre,

If it makes you feel any better, I haven't had a cam bearing failure in a very long time. I use HV oil pumps with oiling system modifications. I run alot more spring pressure than you are probably going to need. I also run good quality cam bearings (durabond).

The first thing you should do is get rid of the mechanical water pump drive and go to an electric. That gets rid of the loading seen at the front cam bearing.

-Mindgame

 

it's not the cam bearings that spin...it is the rod bearings. From my experience, you have about a 50/50 chance of spinning one with a cam swap. I spun one within 500 miles of the new cam. Everything was done clean so i think that theory is out the window. Im my opinion, you should at the very least replace rod and main bearings when doing a cam swap. That might save you some big bucks down the road. I had to have a complete rebuild, new crank, and rods as a result of it.

 

The rod bearings spin from wear and the big end distorts from the extra RPM's and weak rod bolt's and the many times ya wind it up to "feel" the power.Results is a spun brg
The quality of the factory rod brgs are also in question. They are not of quality to take the RPM's and the extra load.

As long as ya got decent oil pressure the cam bearings will probably be OK. The front one takes the beating from the load of the chain and water pump drive.
Ya can change the cam brgs on a stand without removing the pistons along with all the crank bearings. WHY At this point it's time for a rebuild.

 

Do you guys think adding a new timing set to an old engine could be a major cause in spun bearings? In my mind, adding the tighter chain in place of the worn & stretched old one would play a big part in bearing failure. Having said all this, would leaving the stock, worn, timing set on be a decent choice for those not rebuilding the bottom end?

 

I would not open up a high mile motor without putting a new chain on.

Anything on these cars is a gamble. I love my cam, I am sure I will love my new motor, but you have to pay to play and something will eventually happen.

keep it clean, run a good tune with good gas, don't abuse it too much and it will treat you right. There is no "safe" mod on our cars, even factory parts give out and break from normal use.

 

No
A chain set is almost automatic when doing a cam.The new chain will be loose if ya don't get the oversize crank sprocket but it won't have the wear the old one has.
Cam bearings don't go out that much,the only one is the front one 'cause of the WP drive.
When these guys talk about a spun brg after a cam change it's rod brg's for the reasons I posted above.

 

So basically as long as I do a clean cam install, and possibly a higher pressure oil pump to keep the oil pressure up, then replacing the cam bearings wont be necessary? Can they be easily replaced with the engine still in the car?