M42: setting cams at TDC

[The 2002 guy]

Long story short, I’ve put a refurbished head onto a block and am trying to get the cams in time with the crank without the proper Bmw tool. Maybe I sound like an idiot, and maybe I am, but it seems like the issue I’m having wouldn’t be solved by the tool unless the valve to piston tolerance is very small.


So what I’ve tried is lining up the marks on the end of the cam and the cam holder thing (I can’t think of what that’s called) which also made the arrows on the cam gears point up (which is what I’ve read to be correct) but then when I *slowly* rotate the crankshaft try to bring it up to TDC, the pistons seemingly touch the valves on cylinder 4.
Then when I line up the squared ends of the cam shaft up, the way that the bmw tool does, though maybe not to extreme accuracy, the piston still seemingly comes into contact with the valves.


And the marks on the front of the cam do not line up when the squared ends of the cams with the dots are level with each other.
And when the squared ends with dots are level, the cylinder 1 cam lobes are not pointing in towards each other like I’ve read they’re supposed to.


So it seems to me that things aren’t lining up when they’re supposed to be, but maybe I’m just doing something wrong, or I’m misunderstanding how TDCworks on this engine, I don’t know. But hopefully someone can help me out here.


hopefully everything makes some sense the way I said it.

[roguetoaster]

Make sure the cam marked E is on the intake side. Then, with the chain not in place, or the gears unbolted from the cams rotate both cams so the forward most lobes point up and towards each other at roughly a 45 degree angle, and get crank TDC close via the arrow at the oil filter housing. Rotate the cams and/or crank as needed to allow the crank timing to be set locked at the flywheel. Make sure the cams as set as indicated before, and now the marked squares at the rear should be getting close to flat relative to each other. Loosely install the cam gears, set the flats at the rear to be flat relative to each other.

During this work try to get the cam gear bolts centered in their windows and do not rotate the crank backwards (CCW) when the chain is in place as it may bind.

[The 2002 guy]

As a disclaimer, the engine is almost completely disassembled and on a stand. I’ll put the oil filter housing on to get the arrow but what does it point to? I looked at the damper but didn’t see a mark on it?

when the front cam lobes point in towards each other, a piston will touch a valve. So are you saying to adjust the cams at that point to allow the pistons to go up more, or is tdc before the piston meets the valve?

[roguetoaster]

Basically, you should set crank TDC1 and then cam TDC1. Move the cams, remove the cams, or do whatever you want to get there, then set cam timing.

It's really not complex when the engine is in place as you can lock the FW with a pin, but you likely cannot easily do that on your typical stand.

[The 2002 guy]

What does the arrow on the oil filter housing point to? I see the blank space on the damper but I think that’s for the sensor isn’t it? Is there another marking I should look for?

[roguetoaster]

A dot or dash or little notch on one of the trigger wheel teeth. Looks different from certain angles, but is there. Think it's 4 to 8 teeth from the space.

[The 2002 guy]

Okay, so what it looks like is that the cams are in the wrong place. The cam in the intake side has “IN” scrawled on it and the cam on the exhaust side has “EX” scrawled on it, but the cam lobes are pointing in the opposite direction from where I’m told they’re supposed to be, and the crank and cans are unable to be at TDC at the same time. This is a remanufactured head that I bought second hand so I don’t know if whoever reman’d the head put them in wrong, or if someone els took them apart, but it looks like I should swap the cams around. Does that seem accurate?

[The 2002 guy]

I’m pretty sure that someone put the cams in the wrong place, so I switched them and everything lines up correctly now