Slavvy 0 Report post Posted January 30, 2010 (edited) I recently reassembled my m30 cylinder head. I've done this before and know what to do to avoid any stuff-ups (hard lessons learned last time). Anyway, now I find that the rocker shafts slide so easily in the head that the force of the rocker positioning springs causes a couple of the shafts (the intake side rear one is by far the worst) to slide partly outward. This means that the rockers arent quite centered on the cam lobes or valve stems. My engine already shows signs of this in that the wear area on the cam lobes is off-center, but now it is considerably worse and I'm afraid that if I put the motor back together bad things will happen in the head, what with the rockers hitting the cam lobe off-center and possibly missing the valves altogether. In it's current state the head is fully assembled minus the oil spray rail, and the clearances are adjusted out fully. Putting the head bolts in helps the issue but not enough to fix the problem, as the cutouts in the rocker shafts are machined to match the holes in the head and are therefore of a larger diameter than the bolts themselves. Has anyone run into this before, or know how to fix it? I can post pictures later if need be. Edited January 30, 2010 by Slavvy Quote Share this post Link to post Share on other sites
Slavvy 0 Report post Posted January 30, 2010 Buuump... Come on guys, someone must be able to help me out, it can't be the first time this has ever happened. Quote Share this post Link to post Share on other sites
BM WORLD 1283 Report post Posted January 30, 2010 the head bolt locates the rocker shaft inplace , but sometimes you have to hold them in place when tightning them down so they stay centred Quote Share this post Link to post Share on other sites
Slavvy 0 Report post Posted January 30, 2010 the head bolt locates the rocker shaft inplace , but sometimes you have to hold them in place when tightning them down so they stay centred I don't understand. The headbolts only hold the shafts to a certain extent, theyre not large enough to center the rockers on the lobes. Even if the head were on the block and tightened fully, the shafts still wouldnt be in the correct place?? I didn't have this problem with my last cylinder head because the shafts didnt slide freely back and forth. Quote Share this post Link to post Share on other sites
BM WORLD 1283 Report post Posted January 31, 2010 yes i have had this problem before , and just held the shaft/rockers in place while tightning the head bolt so it grabs it . they do have a bit of slop in there if the shafts can move freely . Quote Share this post Link to post Share on other sites
