Is it necessary to swap cam bearings when you're putting in a new cam?
If not, when should you put in new ones? During a complete rebuild?
10-13-2003 05:39 PM
A lot of people don't change them if its a low mile engine, but I would. Not worth the risk.
During a rebuild? always!
10-13-2003 06:31 PM
Replacing cam bearings in a together engine is a real bear. Unless you have some reason to belive that there is a problem, leave them alone. If the engine is apart then by all means replace them.
10-14-2003 07:25 AM
It is almost impossible to replace the cam bearings while the engine is in the car, and get them in the correct position. Cam bearings generally do not wear much in a properly maintainted engine. If the cam bearings are worn, then the whole engine probably needs to be rebuilt. During a rebuild it is imperative to replace the cam bearings, as most engines have a groove in the case around the perimeter of the bearing shell. This groove can only get cleaned out if the bearings are removed.
In summary, if you are just replacing the cam do not attempt to replace the bearings. But do look at the #1 position bearing, the only one you can see unless the engine is disassembled. If this bearing is in bad condition, like scratched and gouged, then all of the cam bearings should be replaced.
11-14-2003 07:52 AM
Could you tell me a little more about how "almost impossible" it is to change cam bearings in a motor still in the truck? I have a strange case, I bought a new engine, 350 Chevy, from a rebuilder. Put it in, tried to prime the pump and nothing. Rebuilder didn't know what was wrong said to crank it and see what happens. Did that for 2 or 3 short runs and still no oil pressure. Finally figured it out, had a dirt dobber build a nest in the oil line from the pump to the filter. Who knew that would happen. He missed it in the steam cleaning and the rebuild. Anyway, cleaned it, cranked it, got oil pressure, but damage was done. The rebuilder is standing behind it, so as a first try to bring the pressure up he replaced all the bearings on the bottom end, helped some but still low. Now we both agreed that it is in the cam and bearings. We decided instead of pulling the engine now and starting over I will just drive it and see what happens. But question remains, if I wanted to try to fix the remaining bearings how much trouble would it be? or would it last as is? This is just a stock motor, no hotrodding on this one. Runs about 20 # down the Hwy, run about 10# at high idle, will pull up to 40-45# hot, cranks up at 60# Thanks for reading this rambiling, any help would be great, Paul
machine shop tom
11-14-2003 08:23 AM
It is impossible to properly install cam bearing is an engine that is in the car. It is very difficuly to properly install cam bearings in an assembled engine.