M117 rounded cam lobe, what are my options?
 

Well, finished the guides in the 380 that has w/ the M117 swap and noticed one of the intake lobes on the drivers bank is wiped. :(

Can the cam and the rocker be replaced alone?

i would think yes. probably replacing all the rockers would be recommended in case some are worn, but i would think you would be ok to just change the cam and one rocker.

tom w

Cool. I have a complete spare Euro 500 motor that needs to be rebuilt, so I may steal the cams from it. :)

Figure I'd replace them in pairs. I could also do the rockers too.

get new rockers while you are doing it..

Or, we can send you a set of AMG spec cams;-)

Setting the lash can be a bit of a PITA w/o a large selection of spacers/shims.

Jonathan

I should use new rockers as opposed to the used ones on my spare motor? :confused:

Another thing I noticed, which I believe attributed to the lobe issue, this locknut at the base of the head was FINGER tight! :eek:

Yes, I would use new rockers. You can get away w/ the old ones as long as you keep them w/ their respective lobe.

They do loosen w/ age/time..not uncommon.

Jonathan

I assume there are torque specs for that lower bolt?

Can you elaborate on the shims required?

I'll need to dig to fine the torque #'s but I remeber it not being terribly tight..

There are a large selection of shims that go b/w the rocker and the lifter. It's critical that you get said spacing correct. There is a special tool used, or you can get by w/ a set of feeler gauges.

Typing out the procedure is a bit long winded..

Jonathan

Is the procedure in the FSM?

might be... it's in my printed manual..

Jonathan

Okay, I'll have to go through the disc and have a peek.

i thought that motor has hydraulic lash adjusters.

what are shims for?

tom w

Swap the cams from your spare engine. Swap the rockers, too. Make SURE to match the rockers (exhaust on cyl #1 goes back on exhaust on cyl #2, etc). Otherwise, you'll need all new rockers.

And the m117's older than 4.5's do have hydraulic adjusters, so I'm curious just like Tom W as to what you'd need shims for...

i think tomguy meant newer than 4.5s right?

tom w

I believe he did..however, they Still have shims even w/ the hydraulic lifters. I'll post a pic or two from the EPC if need be later on.


Jonathan