Head refresh plan

#1

Dyno’d the motor at Thunderhill last weekend – 145. Not bad, but not great. It’s a 200k motor, so makes sense, I think. I was planning on rebuilding a full motor between seasons anyway, so now I’m thinking about doing the refreshed head now for the next event (2 months away).

Bought a long block a few months ago for $100 with about 200k on it. According to the guy who sold it to me, it “was probably boosted by a previous owner”. He had mentioned something about a wet compression test suggesting issues with the valves, so I’m guessing I’ll have to replace something there. As long as the head isn’t cracked, I’m happy with my purchase.

Want to run by my basic plan + questions by people here to see if I’m missing something obvious. I’m also interested if there are obvious better brands to go with. Pricing from Autohaus.

Camshaft: Replacing with Febi camshaft ($156)
Rockers: Replacing with HD rockers ($300)
Rocker shaft: Measure for straightness and consistent diameter. color=#ff0000[/color] Likely reuse.
Eccentrics: Probably won’t need to replace these. Thinking I’ll replace any if I can’t get the right gap.
Eccentric hardware: Reuse.
Valve seals: Replacing with ElringKlinger ($16)
Valve guides: Will let the machine shop determine whether I need to change. (up to $50)
Valve cover gasket: OEM replacement ($17)
Rocker shaft plug: VictorReinz ($4)
Valve collets: Reuse.
Spring retainers: Reuse. I’m assuming this is the terminology for #16 and #20 in this drawing (http://www.realoem.com/bmw/showparts.do?model=1413&mospid=47322&btnr=11_4366&hg=11&fg=25). color=#ff0000[/color]
Valves: Reuse or replace, as needed. I’m assuming it’s easy to find how to measure these properly? Will I probably want to replace the exhaust valves? color=#ff0000[/color]
Springs: color=#ff0000[/color]
Intake/exhaust studs: Wire brush and reuse.
Valve cover: Chrome dipped neon green. (what’s the term used when inserting something meaningless into a long winded speech just to determine if people are listening?)
Head bolts: Likely reuse. I know they’re TTY, but I’m guessing the head comes off again in the next year or two for a bottom end rebuild anyway.
Head gasket: “Genuine BMW”. Are there other brands to consider here? Goetze? color=#ff0000[/color] ($90)
Cam seal: Not sure yet. Probably the Victor Reinz one I used when I did the timing belt on the current motor.
Deck the head: Machine shop (don’t know the price)

My biggest question is around the springs. Can I just measure the unloaded spring heights to determine whether they’re good to reinstall? Is it a good idea to replace these regardless since the motor is so old?

I know there are a lot of questions here. Appreciate any help people can provide.

Thanks!

Som

#2

Rocker shafts: clean and re-use if they aren’t scored or damaged during removal. The rocker shaft plugs shouldn’t need replaced unless you damage during removal. Clean any sludge off the rocker shafts with something that attacks oil and drive out with a large diameter brass drift. You should unload all of the rocker arms before removing the shafts.

Eccentrics: visually inspect for flat spots and replace as necessary.

Valves: Re-use unless they are bent or physically damaged.

Valve guides: Budget more money for labor. This is the hardest part of the job.

Springs: Unless they are weak, rusty, or sagging, I don’t recommend replacing. Your machine shop should check them. Because we don’t rev our motors very high or have aggressive can profiles, excessive spring pressure is not necessary. In fact, less pressure might be better. You just don’t want them to break… Rusty is bad…

Head Gasket: I recommend Goetze. VR is fine for a short term solution but could develop small oil leaks over time. Use new head bolts or look into re-usable bolts. Do not re-use TTY head bolts. That’s dumb…

#3

Do not reuse head bolts.

#4

Relative newby here, but maybe consider new spring retainers. Currently rebuilding my engine after my spring retainer cracked, allowing the valve to drop in the cylinder. $5 part that ended up costing a lot!

#5

Thanks for the feedback!

Honestly on the fence about the head bolts. I know most people replace them and that’s the “right” thing to do. I also know some people who reuse them and haven’t had problems. I remember Scott referencing some MB spec about their TTY bolts being good until they stretch 2mm, or something like that. I don’t know of such a spec for the BMW’s head bolts, though. Anyways… who knows. I don’t mind being a data point on something like this. On the flip side, new bolts are not that expensive. Whatever. It’ll probably end up depending on my mood. :slight_smile:

I’m wondering if I have my terminology wrong on the retainers. I used to think the retainers were the flat pieces above/below the springs (like perches). I’m thinking now the retainers are the collets – the little half-cone pieces with the teeth that grip the top of the valve. Can someone set me straight?

Regarding the springs – can you determine “weak” or “sagging” springs by just measuring their unloaded height? Or do I need some sort of spring measurement tool (which I’m guessing is why you suggested having the machine shop do it)?

Considering the “Genuine BMW” head gasket was $90 and the Goetze is only 30-something – and since I’m probably doing this again in the next year or two – Goetze it is. Man… I have a hard time writing that brand name without thinking of… damn internet.

Can the valves be eyeballed for damage? What’s the most important thing to measure? Should the stems be 90 degrees from the valve face?

Thanks again for the feedback!

Som