I have been reading up on the on the old Cam and/or Heads = Spun bearing and i have done some thinking. There seam to be to 3 schools of thought on this 1. LT1 just are prone to it 2. People spinning there motors to fast and 3. installer error/ dirty install. Well i have a new theory that i was wanting to get so opnions on. In my Factory service manual it shows how to install a new crank sprocket by using a tool that is basicly a gloryfied pipe and driving it on with a hammer. Is is possible that by beating on the crankshaft this way that could have an effect on the bearings after install. Just a thought i know this topic has been beat to death.

 

That's an interesting theory. I heard that it's a rod bearing failure that occurs and not a cam bearing so what you are saying makes sense to me. I made my own tool to install my crank gear. I used a nut that allowed me to slowly press the gear back on. Here is a pic. I used the same tool minus the pipe to install the hub. I must say that it would take some serous pounding to install the crank gear if you didn't use the press on way that I did. Maybe enough to fubar the rod bearings.

http://community.webshots.com/photo/...92266903pfzjxy Crank gear tool

http://community.webshots.com/photo/...92267075JJvBCX Hub tool

It's been about 10k miles since my cam and head change. No problems. How did everyone else install thier crank gear?

JD

 

Thats a clean lookin install you have there. I never thought of running a couple of quarts down through the block to clean it all out. I think I'll try that.

 

I never removed the crank gear when I did mine and I spun a bearing. So in my case this theory don't apply. Interesting thought though. It might account for some peoples.

 

With the tool you made PoorMan you just ran the threaded shaft into the crank untill it bottomed out? How hard is it to press on?

 

How did you put the hub on? I suppose that applies too.

Yes. With a long wrench it's not that hard to turn. Just takes time.

JD

 

Gotta remember who gets priority when it comes to oil. Cam, Mains, and then Rods. Rods get the most stress and they're last in line. Plus cam and main bearings have constant pressure while rod bearings only have pressure half the time because of the way the oil passages in the crank line up with the main bearings in the block.

But when you put a new cam in the bearings will most likely wear slightly and decrease the amount of pressure to your rods.

Sorry for the crappy explanation. Kinda hard to explain. Anyone who has built a SBC would know what I'm talking about.

 

I didnt replace the crank gear either, and my cam and rod bearings were fine. it was the last main bearing that wore out on mine. and when I did my cam swap, I also rinsed down the entire eng. with clean oil. another step I took to make sure there wasnt any debris in there was to rinse the inside of the oil pan before I put on the timing chain cover with parts cleaner. I took out the oil plug, had the car at a slight incline, and sprayed the cleaner all through the bottom of the pan rinsing itout. then came the oil again. one more thing, after I initially started the car, I had it running for a few min.s to make sure nothing was leaking, noisy, etc. then I changed the oil before fully running the car. I changed it again at 100 mi.s. my eng. only lasted about 380 mi.s if I remember right. I think I fell into the higher rev.s/more force on the crank due to the extra power/high mileage eng. category.
chris

 

thanks 94GreenZ28 i got what your saying and it makes a lot of sense

 

I'm bringing this back from the dead because i think it contains some good info. What I'd like to know is, how many bearing failures occured after a cam swap for people who hammered the balancer hub back on Vs. the people who installed the hub with the correct tool(pulling it on). I don't think the crankshaft gear is much of a problem since it doesn't take much for to get the bad boy on there, hence the reason for the shop manual instructs people to beat it on. Anyone with bearing failures, How did you install the hub? Those of you whose bearings did not take a crap, what was your method for the reinstallation of the hub?

 

I installed mine by pressing it on with a threaded rod & nut, not hammering it. Spun a bearing(s) at 700 miles. I was very careful about dirt, and spun the engine to around 6200-6300. Had one missing retainer on the Comp Rs and two bent ones.

So.... I've concluded nothing.

 

Think a lot of factors go in. I had nearly 10k miles after my first cam swap and I spun 2 rod bearings. Spun them at 125k miles. I just did a cam swap on my new motor (motor has 500 miles on it) so I pray I don't spin a bearing

 

Wre those the troublesome Comp Rs listed in the sticky thread?

 

wow, old thread! I used the factory Jtool, since Im a GM tech

 

Yes, but I really don't know if that caused the spun bearing.