Tricky crank no-start problem

[DonaldFoss]

[mention]80stech [/mention] Thanks for the clarification. On the lapping, that’s interesting and worth bearing in mind. I did as advised by my dad and a Toyota mechanic in the family, I’d only done SBC valves on iron heads before. Lapping was supposed to fix whatever grooving was there. I’m doing the valves myself as part of the adventure. When I told my dad about the leaking, he told me to put them on the engine anyway and they’d probably fix themselves. I should have tested the valves before doing anything to them.

I’m 54 and yes, I still go to my dad for advice with mechanical stuff, any type of mechanical stuff. He’s forgotten more than I’ll ever know, and he doesn’t seem to forget anything. My brother was a F16 crew chief and airplane mechanic. Me? I was great at cross threading things. Maybe that’s why I did electrical engineering and computer science.

Given the cost of good valves, and money I already spent, I might just buy another head off ebay, put a second head gasket on and try that. They were around $330 last I looked. If I like the new-to-me head, assuming everything is working, I’ll get it decked and port both sides again.

This intake is a stock M54 attached via 7mm bolts versus the studs that are stock to a M54 engine. I like bolts better, less likely to drop into the intake or anywhere else. Personal preference I guess since I shake and drop things too easily to deal with.

I did the spark gap test tonight. Since it’s just me I used a 4k camera and reviewed footage after each test. I’m not certain about the markings on the device, they didn’t line up with my calipers so I measured out manually 10mm, then 15 and 20mm from the tip of the electrode. I got consistent spark over 4 strokes at 10mm, 15mm and 20mm. One time it arced to the turbo, about 5 inches away, so I put a piece of wood in front of the turbo to prevent it from happening again.I think the coils are ok. I was really about to order some supposedly higher energy coils for forced induction too, but from what I recall, 15mm is recommended minimum spark gap length for forced induction, and this exceeds that spec.

I’d like to have a Trillium induction unit that would measure voltage too, but they’re a little pricey and wouldn’t be here for a few days anyway.

When reviewing the INPA guide for removing Vanos, there was a handy quick test for timing. If you turn the crank until the first lobes on both intake and exhaust and pointing inwards to the #1 spark plug recess, and you have the cam holders installed on the back of the cams, the holders on the intake side should be flat or less than 1mm high at highest level, and the exhaust side should be flat. If this is true and you have the intake/exhaust cam on the correct sides, BMW says timing is within spec. If it’s not raining for a while tomorrow, I’ll pull the valve covers off and check this.

I loosened and cracked open the downpipe from the turbo to see if that made any difference from the exhaust puffing sound. Not really. This doesn’t eliminate exhaust totally, but almost.