I seem to have gotten myself into a pickle...

Last january (2013), i found that my 2000 l6 block was cracked behind the water pump. since then, I've not had ANY time, nor money to do anything about it. i moved into my own place and actually had became the father of twins on the 5th.

Last week i had taken in my block (with a replacement block) into the machine shop for the rebuild. I'm no master mechanic, so i didn't trust myself to build it myself. I had also taken in a master rebuild kit that i bought from rock auto last november.

After the initial inspection they found they will have to bore out the cylinders a bit and i'll need to get a new camshaft, with "under 10 bearings" (someone can help me on that difference too, thats just what the machining guy said) for the cam and crank shaft..

I'm hoping to get some input on the basics, and the not so basics of the cam.. I do understand how it works and why it works, and what not. but i was just thinking to build it all back to stock form.

Now that i'm needing a new cam, i was wondering what my best options would be..

When people go bigger on the cam, is it the shaft itself? or is it the gear for the timing chain? Or both?
if i were to get a new cam, is there a dimension choice for the shaft itself that would be a good idea?

Any help and input would be great. in other words, what would YOU do?

Thanks in advance..

Jamdeeper

 

Congrats on the twins!

What the machine shop is saying sounds ordinary and customary to me. Due to block wear in the camshaft area, they will put in camshaft bearings that are .010 oversize. The camshaft itself, in the bearing area, will then have to be .010 undersize so that everything mates up.

They are not changing the lift and duration of the lobes, so everything remains stock performance-wise.

 

What the machine shop is telling you is that they're going to "turn" the crankshaft and possibly rebore the camshaft bearing bores to repair the bearing surfaces.

They will be grinding the bearing surfaces (journals) 0.010" smaller than factory, which is a standard undersize. This is to remove imperfections and fix bearing clearances that have become too large due to wear.
You'll match them up with new bearings that have 0.010" thicker liners and everything will be nice and factory tight again.
These size changes have nothing to do with performance or cam or crank operation. They are merely to repair and re-clearance the bearing surfaces.

When folks talk about going to a "larger" cam, they are talking about lift and/or duration. The cam's job is to open and close the intake and exhaust valves. The valves open a certain distance (lift) and for a certain length of time (duration) based on the size and shape of the lobes on the cam.
Changing lift/duration can increase the performance of the engine by letting it breathe better.
It can also create an engine that won't idle, hates low-rpm operation and a host of other things. You have to match the cam to the rest of the motor and it's intended use.
The OEM unit on the 4.0 really isnt' that bad, but I've seen others here with aftermarket units they seem to like.

 

Things like this is why you let the engine builder buy the parts "AFTER" the machine work is finished. That way he knows exactly what size he needs to buy. Plus with customer supplied parts usually "No Warranty" by the builder!

What you did was like taking your bacon/eggs/hash browns into a restaurant and asking them to cook it for you, same difference.

Plus I hate buying any complete engine rebuild "KIT" because you have no control over a lot of the parts used. It is in those small parts where they cut corners to beat the completion, some of them being very important.

 

Very true!
A lot of shop won't instal parts the customer because of liability.

 

I've decided to just stay stock. I have been through enough with this jeep the past 3 years. I just want it done. Any good places to start looking for a camshaft?

 

Just tell the peeps building it you want the stock grind, done.

 

I was going to see if I could find my own cam shaft. It will be $1200 all done after I find me a cam...

 

Never buy parts before it gets to the machine shop.

 

Have the machine shop get the cam. They know your engine. My shop got me a melling cam.