cam trouble

[natedogr]

IJ: thanks for the info. if it comes to that i guess i'll have to do that. when you say cap face do you mean the bottom of it, where it mounts to the head?

if this shop doesnt work out then i'm gonna find me a shop that has worked on 7m's. i should of done that in the first place.

 

[Poodles]

yes, lap the bottom of the cam caps where they touch the head to close the gap

 

[Suprapowaz!(2)]

rod knock engine?

mine looked as bad... but the place does 7M's and said it was normal (was a rod knock engine)

No. Broken ringlands on #1 piston. Missed third and over-revved bad. Car sputtered & died at the end of that pass. Started it back up and car continued to sputter. Found #1 cylinder to have around 15psi, wet test bumped it up to about 90psi. Tore it down and found this.

 

[pogoism9]

if you have previously had a BHG, water in the oil will wear your cam saddles out, thus causing bad cams. I know I have several 7M's in the shop that have the same problem.

 

[natedogr]

well i got my first two sets of cams from two engines i picked up. one had a BHG and the other had a dead cylinder. so for the first set i guess it makes sense for the cams to be a little messed up, but for the second one i dont know.

 

[3p141592654]

Those cam bearings look really bad. As mentioned, 7M cam journals always look crappy with marks in the soft babbit, but the aluminumn bearing surfaces in the head and cam caps should be pristine, not all gouged up like in those photos. Also, the grooves in those journals look really deep, not just in the soft coating.

There's a good bunch of posts for lapping the cam caps here.

http://www.supramania.com/forums/showthread.php?t=34673

Its a good thing to do on any rebuild since those bearings always seem to go out of spec which leads to a noisy valvetrain.