M50 overheating & head cracking

[hoveringuy]

There's another bar that goes over both of them and locks them together. They are extremely tight, the cams don't budge.

I may get another 1/4 degree of accuracy with the correct tool, but this is close enough for me.

I wish I had all of the BMW factory tools to do this but I don't. For something that I will most likely use once I just can't justify the outlay.

[matt]

What if the last guy who put the motor together didn't time the cams right?

[hoveringuy]

What if the last guy who put the motor together didn't time the cams right?

Huh? I thought they were timed by placing the square ends 90 degrees to the plane of the head with the dots up on each cam. Does the factory cam timing tool hold the cams at an angle different than that?

That is a detail that would be important for me to know!

[matt]

A) I don't think the ends are actually square, I think they have a bit of a taper. B) I am not sure if they're straight up and down or not. My cam tools are at the shop and I won't be until maybe next week.

[hoveringuy]

That would be a great data point... is the tool set to exactly 90?

I plan on setting the timing and then double-checking for 90 degrees against the plane of head with the bolts tightened.

[PiercedE30]

I've seen it timed wonderfully with just a flat edge on the top of the cam blocks.
Oh, and when you get the head cleaned, put up some pictures of the combustion chamber. I'm curious about the lines that are going between the valves in the previous pictures.

[hoveringuy]

It's tougher to see when they're clean but there are lines running across each chamber. Part of the casting process, I guess.

BTW, are these heads considered Hemi?

[PiercedE30]

Cool, yea those are casting marks. The common failure point is cylinder #4 between an exhaust valve and a head bolt hole (typically) or between the valves.

[matt]

I've seen it timed wonderfully with just a flat edge on the top of the cam blocks.
Oh, and when you get the head cleaned, put up some pictures of the combustion chamber. I'm curious about the lines that are going between the valves in the previous pictures.

Wonderfully? I call bullshit. There is ONE way to time the motor properly, and it takes about 5 inexpensive special tools.

Oh, and you need to send the head to a machine shop for testing.

[golde30]

wow, that was one dirty motor when you opened it up. i personally would have just sent off the head to a machine shop to have it cleaned/pressure tested at least.

[hoveringuy]

Yes, I should have it pressure tested. Yes, I should use BMW authorized tools. However, I have a schedule, a budget and other factors to consider.

It will get a new headgasket and carbon cleanup out of the deal so I'm calling it good. I will have the peace of mind of knowing that's been done.

If this were an S motor and I would do it differently and budget more time and money. It's not.