B34 head advice

[Jasco1]

Hi,

In the restoration process of resealing the motor on my 88 535i with 175k miles, I took the head to a machine shop to be rebuilt. The machine shop sent me a pic and it appears that the rocker shafts are not correctly aligned. The left side is sticking out and the right looks like there are no threads for the Allen plug to go. I was under the assumption that both side and ends had 4 threaded Allen plugs that go in to keep the shafts from moving about, as in the sample pic with orange gasket material. I did not take before pictures but have seen other B34 heads that have black Allen plugs sitting flush. This angle is from the back where the duck gasket and flat plate go. Am I correct that something is off here or are there in fact B34 heads that have the rocker shafts held in place by only the head bolts? Thanks for any advice.

Jason







https://drive.google.com/drive/folders/ ... 5HB7_VZXrz

[Mike W.]

No, the rocker shafts are just held in place by the shoulder of the head bolts. The plugs which may be allen, may be slotted (I think) or just a pressed in plug only serve to plug the rocker shaft and control oil. My guess is the one that's sticking out slightly just slid over from the pressure of the rocker springs, sometimes they do that. Other times you really have to drive them out.

[Jasco1]

No, the rocker shafts are just held in place by the shoulder of the head bolts. The plugs which may be allen, may be slotted (I think) or just a pressed in plug only serve to plug the rocker shaft and control oil. My guess is the one that's sticking out slightly just slid over from the pressure of the rocker springs, sometimes they do that. Other times you really have to drive them out.

Mike,
Thank you for the insight!

[Jasco1]

No, the rocker shafts are just held in place by the shoulder of the head bolts. The plugs which may be allen, may be slotted (I think) or just a pressed in plug only serve to plug the rocker shaft and control oil. My guess is the one that's sticking out slightly just slid over from the pressure of the rocker springs, sometimes they do that. Other times you really have to drive them out.

Mike,
I believe you had a write up about M30 heads on FirstFives some time ago that I came across. I understand there are four unique and seperate rocker shafts with four different part numbers. Is there a chart or diagram that shows which one goes in each location? I grabbed my rebuilt head on Friday and rear intake rocker shaft is so loose, as in the pic from my first post above, that it’s making the rockers not align on the cam. The couple solutions I have read about were to put a nut or spacer under the rear plate to push the rocker shaft into its correct place or the other possibility is the rocker shaft may not be in its correct location. The shop I used builds very high end race motors and I can see each rocker arm now has a labeled etched location on it # I1,E1 etc. I’m guessing that everything got put back exactly as it was removed but I want to make sure before everything is reassembled.Even when I put head bolts in place the rockers are still off center from the cam lobes. There are several post that discuss this issue but none that show an actual placement of the rocker shafts.

[Federico]

As for the shafts, there are 2 long ones (front) and 2 shorter ones (rear).
But, the Intake ones each have an oil feed hole at a headbolt recess. Therefore, you can tell which goes where without marking them.

In the photo below, you can tell that #1 and #3 starting from the left are the intake ones because of the oiling holes.
https://www.iemotorsport.com/product/ro ... t-set-m30/

Also, I like to use 1/2" bolts (1 per shaft) to locate them when installing the head. They hold the shafts nice and snug and centered. Once you have applied some torque to the head bolts, the shafts won't move.

So, maybe get the 1/2" alignment "pins" first, and if everything looks right with them maybe you could peek down the very first and last intake bolt bore to check for the oil hole.

[Mike W.]

If the rocker shafts aren't in the right position, the rocker arm won't be contacting the valve stem correctly, if at all. I always just lay them out on top to correctly locate them.

There are those who feel each rocker arm should be exactly where it was before, but since valves are not generally located in the same hole, and there isn't any reason to, especially if a valve job has been done, there's even less reason to put the rockers back in the exactly same place.

[Jasco1]

Guys, thanks so much for the tips. I’ll grab several 1/2” bolts or dowels and use them to align everything. Upon further inspection, the intake rocker shafts do have the two oil feed holes on the first bolt hole and the last. This is one area that is not highly covered in forums.

And…..Happy Birthday Mike!


Thanks again.

Jason

[Mike W.]

And…..Happy Birthday Mike!


Thanks again.

Jason

Thank you very kindly. I'm always surprised when people know that stuff, I'm not on FB or anything, I know all that info is out there, and while not a privacy freak, I don't particularly volunteer it. Whatever, than you for the greetings!

Back on topic, I have evolved to drilling a 1/16 hole in the forwardmost cam oiling hole. I used to have some numbered drill bit, but eventually decided to just use 1/16. Now if the banjo bolts come out, the cam can get really ugly, but even without it, #1 sometimes seems excessive wear. So I try to get more oil out there at the problem child. Kind of an insurance policy, as many places that get oil, I doubt a slightly larger oil port on one cam oiler sprayer will do anything to oil pressure. I know there is a school of thought that crimps the oiler bar, but I fail to understand what that really does. In other words I don't do it.