Junkyard 325i Cylinder Head

[scarecrow]

I pulled a 885 head from the junkyard the other day for a 2.7i swap. The timing belt was intact, no bend valves and all the rockers seem to be in good shape as far as I can tell. What should I freshen up on this thing before I bolt it too the block?

[NoM54me]

Check the cam lobes for any wear.

[jeffnhiscars]

And swap the valve stem seals

[SlamedIAm]

You're going to want to get the head pressure tested for any cracks. Checked for flatness and most likely resurfaced. Valve guides should be checked and replaced if necessary. Check out the valves to be sure nothing is bent. Have them lapped and replaced the stem seals. Check the cam lobes for excessive wear and flat spots on eccentrics.

Don't forget to replace the rocker shaft plugs.

[Jaxx_]

I would at minimum disassemble the head to replace valve stem seals and inspect everything. Cam journal inspection to verify that oil pressure isn't going to be a problem, and also cleaning the rocker shafts to make sure nothing will cause starvation failures down the road.

If you're doing it on a budget and the head is flat, I doubt that there is anything wrong with the head. You don't need to take it to a machine shop, but it's worth it for the peace of mind.

clean it with denatured alcohol if you don't have it cleaned by a machine shop.

[digger]

take it to a proper shop with experince with the M20 head, they will know what to do. dont assume anything

[MR 325]

^ Good advice.

The minimum I would personally do to ANY M20 head is grind valves, grind valve seats, replace valve seals, and resurface. Like I said, that's the minimum. Anyone who says their head doesn't need to be resurfaced is living in a dream world. Even a head that lived the best life possible and never got hot will be slightly warped. Do it once, do it right.

[Jaxx_]

Anyone who says their head doesn't need to be resurfaced is living in a dream world. Even a head that lived the best life possible and never got hot will be slightly warped. Do it once, do it right.

are you saying that a head that has less than say .0013" variation in flatness needs to be resurfaced? I don't understand the logic. isn't the flatness spec something like .003? Do you really want to take away from head thickness and require a thicker gasket if it isn't needed? I find it marginally hilarious to think that a motor that had the head off after 3000 easy miles would need to have the head decked according to what you're saying.

Additionally, if the head is warped, it's best to instead have it reflowed, then decked. You risk having the head re-warp when it gets heat cycled if you only have the head decked.