I hear a lot of stories of people changing there cams on 100K mile+ cars and some don't last long. I was wondering if its because they didn't let it breakin properly and caused a spun bearing or whatever. If you did the swap of head and cam and babied it for 500-1000 miles could this greatly increase the chances of a problem free motor? Someone mentioned they installed the cam with a hammer so improper installation would be a key factor. I have read that the motor has run forever with the stock cam and with different size cam it isn't able to adjust to the higher and more radical one. What exactly are the odds of a new cam not ruining my motor?

 

I would like to know also I'm putting a cc306 in my 94 with 118xxx

 

Journals being a different size is the most common cause of problems. Followed by using too high a spring pressure to break it in being second. I always suggest using a much weaker spring to break in then replace the final springs after it is done. Don't forget to wash off the cosmoline before you install it. It also wouldn't hurt to prime the oil system good before starting up. Even if it only means cranking many times with the plug wire off, it's better than nothing.

Oh yeah, don't confuse the break-in lube for flat tappet cams as the same used for roller cams. It's not.

 

Thanks for putting a smile on my face!

 

Most cam failers are do to in-proper breakin or installation, if its done right & care is taken, plus the engine has a solid background (well maintained throughout its life), you'll mosy likely never have an issue, my 97 has 157K on it, i wouldn't be worried about doing a cam change on it, it has been well cared for & mostly seen highway miles, you can basically tell if an engine is healthy or not, do a compression test first, make sure the rings are still tuff, 100K miles isn't jack on those LT1s if they have been well maintained, like i said, my engine feels & runs like it has 50K on it.

 

As long as you lube the cam properly at install, break-in should not be an issue. There is no real break-in for a roller cam. Your taking an engine with well worn bearings and adding a cam that will undoubtedly "cause" you to run it more often at high RPMs. Lack of good oil pressure at those RPMs is not kind to bearings. If your engine has marginal oil pressure before you install the cam, consider putting in a new oil pump with a higher pressure spring. It is not a substitute for new bearings, but might be enough to keep the current ones happy.