Rebuilding the head - tips for remove/replace?

Stevehose

Stevehose

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Starting a new thread on my exhaust valve leak project - I've decided to pull the head and have it gone through. I will be doing the pulling and replacing, just dropping it off while my car gets some detailing in the garage instead of sitting in a shop. Any tips as to what I should look out for when removing/replacing? Do I need any other parts besides a head gasket set and head bolts for my part in this? New head bolt washers or can I re-use? Should the shop replace the springs? thanks.
 
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I just did this and most people say to use new bolts on the head but i have seen conflicting arguments on whether they are stretch or not. The new and old i had looked identical.

A full head gasket set should be all you really need. I used Elring as a brand and was happy with it.

Are you going with stock for the cam and stuff? If not perhaps some Schrick springs would be an upgrade?
 
You don't need new bolts. They're reusable. Get an angle guage for final tightening. Be sure the shop has the specs for things like valve guide clearnace, etc.

What year head? As early valve seals are different. Check with the shop as they sometimes purchase the gasket set and give you what's left. Or tell them you'll give them seals.

I doubt that the head needs skimmed, but just in case bring your upper timing cover to the machinist.

First fives has a good head article by Mike as long as you don't start down the slippery slope.

For a little more money, I'd CC the chambers, and port match the intake for the first few inches.
 
i am not in the position of discussing with jerry, but for 40usd, i would install new bolts
you do not know if they had gone through the plastic side of the diagram, because you probably dont know in which way they were tightened the last time, i discussed about this before, you can do a three stage tightening process in torque values only or torque + angle, also if the first one you might have gone through retorque, as it is my case
for peace of mind, new bolts
check the wear of the lobecams and the four long rods, walloth has a nice set of hardware including retainers, washers, and eccentric bolts and nuts
the head changed in 1973, so if it is the old one or the later one, the valve seals are different, older are less diameter
a important issue is the hollow tube that spreads the oil, it can be assembled wrong, so check that the little holes are placed in the middle of each two valves, in this same point, check the washers of the banjo bolts, and install the bolts with loctite adhesive
this is what i remember
good luck
 
Some suggestions:

Make sure the engine is at TDC #1 before disassembly.

Mark distributor & rotor position before removing - so you get it at least close for tuning after start up.

Take a photo of the backside of the upper chain sprocket so you remember its position. The end of one of the bolts through the sprocket should align with a mark on the head (just behind the sprocket). It should be straight up (relative the the engine slant).

Make sure all oil is removed from the bolt holes in the block before reassembly.

Other items you may need:

Triangular gaskets for exhaust manifold to downpipes.
Downpipe to center pipe gasket rings.
New heater to back of head hose?
 
Great info gruppe, much appreciated.

It's the original '72 head so duly noted on the valve seals - should these be replaced regardless of condition?

I've already installed the banjo bolt wire kit.

Porting is a good idea.

What about headers for a stock engine? Did I just say that?
 
trivial tip

Secure the timing chain to the sprocket with a bit of safety wire tight enough so you don't lose alignment at the top. And you have to keep it tensioned upwards so it doesn't go off by a tooth on the bottom sprocket (mini-bungee and a stick across the top of the fenders is how I did my scruffy 2002's in the old days).
 
HEad

Porting is a good idea.

What about headers for a stock engine?

And the slippery slope begins! If you are going to do that, you should consider a cam/double springs and with all of those changes, you might need a fuel retune because the AFRs might be off a bit.

And if you want to get really slippery, throw some hi comp pistons at it while you are in there :)

Its fun spending someone else's money for a change.
 
If you go with headers (and a Cam??) ask Pamp about the heat shields he adapted for his Coupe. Also, get the headers ceramic coated as the marketing blurbs state you can lower cabin temps by doing this. Oh yes, then Dyno Mat your interior....might as well seam weld the rear floor sheetmetal while you are at it!

One other tip. Get an assistant for the moment you lift the head off and lower it back on. I remember taking mine off by myself on my Bavaria, but I was a Lot younger then and if I recall correctly it was a handful. (Maybe I am thinking about the cast Iron slant Six head I removed on my Valiant...)
 
compression is King- all that other stuff like cams and springs and porting is wasted on a 8:1 engine. (9:1 is where you start to have the real deal and everything above that is better.
 
Reinz?

All excellent advice and appreciated.

Reinz gaskets ok? Can't seem to find Elring or Goetz anywhere. Have read mixed rviews on Reinz.
 
Agree on having someone help you lift off head, don't want to get a hernia. Time to clean up side of engine if dirty and get to the starter if not replaced with the M3 starter. I had valve cover tumbled and cleared, looks OEM and easy to clean. You can do same with water divider, thermostat housing, from timing cover, manifolds. I replaced PS hoses when head was off as they weep and create a mess. Had new PS hoses made for much cheaper than BMW prices too. Like everyone says, once head is off there is lot you can access and spend time on so don't regret later that you didnt do something.
 
One more thing to keep in mind, just having gone through this, is that your "new" head may not have the mechanical fuel pump through hole for the push rod. For the same cost, and far less hassle than an electric pump, I had a machine shop drill the hole for the push rod since my replacement '84 head (thanks Don!) had the mechanical pump boss machined into it.

You will need the rear cam cover gasket (duck shaped) and the gasketed washer and make a note of which bolt it goes on. The rocker cover studs on my new head were different in length so keep the studs from your old head.
 
Alternate vc finish

I used to clear underhood parts but they'd yellow and peel over time.
A friend convinced me to try catalyzed silver Over etching primer. that's very close to natural aluminum in color.
This stuff is really tough, wipes clear with windex, doesn't yellow or peel. But it doesn't look stock. Really great on transmissions and other bits that get oily.

Finally, check facts on ceramic coatings for heat reduction. I believe some big name product do not perform.
 
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springs

according to the blue books and IIRC, get the springs together and see that they have the same uncompressed length.

I suppose you could hang each be a thread and bink it with a wrench to see they ring, an odd sound would be suspect for a crack.

I think the springs are not generally replaced unless changing the cam.

Pictures during disassembly will help.

Helped a pal with a cylinder head R&R on his 735i a while back. The head's not unmanageable by one person but I sorta did climb onboard. I'm six foot six so there might have been some reach and leverage advantages.
 
Stevehose said:
How about springs?
Click to expand...

Since you brought this up . . . .

As Honolulu mentioned, spring height should be uniform. But there is far more to that subject. Springs can weaken over time - and our cars have seen a lot of time. If a spring is weak, it can result in valve float. Chances are if you do not see red very often you will never notice an issue. Nevertheless, if you have any reason to be concerned about the age/wear of your valve springs, you or most machine shops, can measure each spring's tension by comparing them with a new spring. The shop manual provides specs for spring length and various tensions. http://www.e9-driven.com/Public/Library/BMW-E9-Manual/pages/en/11000000.html Haynes briefly mentions the process here: http://www.e9coupe.com/tech/autobooks/chapter1/autobooks_manual_020.htm ("valve springs")

There are several tools available for valve spring testing. The traditional method uses something like a simple arbor/drill press. http://www.oldchevytrucks.com/blog/index.php/2010/02/valve-spring-test/

Regarding the reuse of headbolts, many of us have been reusing the same ones for years. Obviously, galled threads shout for attention. Locate a brand new - unused bolt. Measure its length with a micrometer and compare it with your used bolts. This ought to tell you if there are deformities. Be aware that head bolt design has changed over the years in that some had different shoulders. Plenty to read (and argue) here> http://www.e9coupe.com/forum/showthread.php?t=10288

HTH

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spring_test.jpg
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Steve,
With the triple webers that you are running, IMHO it would be worth it to send your head off to someone like Metric Mechanic or Korman to have some serious head work done. (porting and polishing, Schrick Cam, double valve springs etc) Of course this all costs a few duckies.
My 02 cents worth
 
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