cylinder head swap

[Sharky1980]

Hello. I'm new to the forum, but have had my 1980 528i for a few years now, and spent a lot of time revisiting the FAQ section. i was my daily driver, until it blew a head gasket. Now I'm currently in the middle of a head swap, from the early casting [1 250 019] to a later casting, from a '86 635CSi [1 277 358]. Preparing for re-assembly, I'm comparing the two heads and head gaskets, and noticed a difference that I'm concerned may be an issue. The 3.5L head [and blocks] have a small water jacket passage way, approximately 6mm in diameter, tucked up between the cylinders on the exhaust side. There is also a corresponding space in head gasket, however, the 2.8L block is solid. I'm concerned this will cause problems if I don't block it off in some way. Have any of you seen / addressed this?
See attached pics, and thanks!

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[Sharky1980]

...and here is a pic of the block

IMG_0308_m.jpg (99.38 KiB) Viewed 32027 times

[Mike W.]

Not to worry, just bolt it on up.

You do have the right cam in there or adapter nut, correct?

[maybeillbuyit]

I notice piano head pistons, so thats a euro dirty engine?

[Sharky1980]

Thanks Mike W. I had the machine shop swap cams, so yes, I have the correct distributor drive / cam.

[Sharky1980]

maybeillbuyit - um, I dunno. This is my first BMW [car], so I still have a lot to learn.. Are piano tops only euro / high-compression? I know it's not the original engine, but haven't dug in deeper that that yet.

[maybeillbuyit]

I'm not positive myself. I've always heard about piano top pistons in the high comp euro engines. No first hand experience myself. I didn't know they came in NA engines. Worth looking into.

[maybeillbuyit]

OK so I was curious about those pistons and asked my BMW guru buddy and he said all b28s had those pistons so its nothing special. Sorry I got over excited. Another guy I know found a 528i in a yard a while back with the head off and asked me the same thing.
I'll be doing the same thing later on my car. I think the guides are worn and need replacement. Instead of redoing the old existing head I've got a head from an 81. Did you replace the valve guides?

[Mike W.]

US spec E12 2.8's had a small raised piano top crown, 2MM IIRC. Early US 2.8s, such as 69-71 E3s and E12 euro had higher compression, 9:1 pistons with a larger crown, ~6MM or so. The pic looks like more than 2MM but I can't tell for sure.

[Sharky1980]

Measured my pianos: 6mm tall. Looks like I lucked into higher compression. Sweet!

EA38B08F-2F27-426F-BB39-5574EA738F7A.jpeg (129.36 KiB) Viewed 32003 times

[Sharky1980]

OK so I was curious about those pistons and asked my BMW guru buddy and he said all b28s had those pistons so its nothing special. Sorry I got over excited. Another guy I know found a 528i in a yard a while back with the head off and asked me the same thing.
I'll be doing the same thing later on my car. I think the guides are worn and need replacement. Instead of redoing the old existing head I've got a head from an 81. Did you replace the valve guides?

According to the machine shop, my new-old head was is pretty good condition already, so no valve guide replacement.

[maybeillbuyit]

OK, lucky you. Saved some expense there. I had the same on a previous head redo

[maybeillbuyit]

Measured my pianos: 6mm tall. Looks like I lucked into higher compression. Sweet!
EA38B08F-2F27-426F-BB39-5574EA738F7A.jpeg

OH wow, thats awesome, Mike whats the HP difference in those engines?

[Mike W.]

Measured my pianos: 6mm tall. Looks like I lucked into higher compression. Sweet!
EA38B08F-2F27-426F-BB39-5574EA738F7A.jpeg

OH wow, thats awesome, Mike whats the HP difference in those engines?

Not a ton, euro 528i was 177HP, US 169HP. Still a little more fun.

On valve guides, in my experience the seals are more important than the guides, so I assume you are using new seals?

[Sharky1980]

Thanks for the info Mike!

Yes, the shop installed new valve seals. Good to go.