engine and drivetrain Cylinder Head Rebuild... Advice??

[2002inthewoods]

Hello Everyone,

 This winter, while it snows like crazy here in Vermont and driving is a silly idea, I decided to change the valve seals and upgrade the camshaft in my 1976 2002. This decision came after came after a lot of tinkering around during the driving seasons last year - I installed a weber 32/36, mechanical advance distributor, full exhaust system (combination of IE's "stage 2" headers, and an Ansa resonator and free-flow muffler). The car was running smoothly, sounding very nice and all but seemed a bit down on power. I did a compression test and the results were surprisingly good. The only thing that really stuck out at me was smoke (and smell) under deceleration from higher rpm's (for example: downshifting into 3rd getting off the highway using a sportable off-ramp: I couldn't see the smoke from the driver's seat but a friend following me noticed, although the smell was obvious and almost immediate from inside the cabin). My diagnosis was valve stem seals.... (I'll let you guys be the judge of whether or not this was the correct assumption).

 So, I got the head out of the car, cleaned things up a bit and got going. Everything came apart with relative ease, with the exception of the rocker shafts which surprised me. I succeeded in removing the valve springs with the use of a really crappy auto-zone valve spring tool, changed the stem seals after ordering the wrong style and having to wait for the correct parts to arrive, and reinstalled a set of schrick springs. Everything in the valve/spring department seems to be okay. However: I am now at the stage where I'd like to install the new rocker shafts that I have (didn't feel comfortable reusing the old ones after struggling to get them out) but I'm a bit nervous and have some questions....

  Luckily; one of the new shafts was labeled "exhaust" so I know which side is which, and which direction they're supposed to be facing because of the notch for plate that holds the cam in place (a new IE 292 camshaft). I'm worried about how exactly I should go about reinstalling things though.. what I mean is:

As I lightly push the rocker shaft along - do I just slide the new IE rockers (reusing the old ellipticals which didn't seem so bad) and those special washers that cover the rocker holding clips? Then once the shaft is all the way in - install the little "rocker-holding c-clips (???)" and the new IE rocker locks that I also purchased on the other side of each rocker? Is there a correct gap that I should have in between each rocker and lock? Is there a specific torque that I should set the rocker-lock bolts at?

.... Does anyone have a detailed picture or diagram of how the clips / washers / rockers / shaft should be assembled? The last thing I want to do is be the idiot who got all these lovely new parts just to neglect a little detail here or there and destroy a previously functioning, although not seriously performing, 2002.

 

    Any and all help is much appreciated - I certainly couldn't have gotten this far without you guys!,

         Guillaume

 

P.S: I slid the new camshaft into place and it seems to spin rather nicely... I'm hoping this indicates that the head is not too badly warped. I'm reusing the old rocker clips and washers on new rocker shafts- is this okay? Does anyone else live in the upstate VT/NY or Quebec region?

[jdeitch]

I just did this same job.  Check out my post titled Schrick 292 cam install.  Special tool makes this job MUCH easier!

 

I tried to link the post but that functionality seems to have gone away for me ;( 

Edited January 8, 2014 by jdeitch

[AceAndrew]

Guillaume,

 

Here's a quick reference shot of a head running the Ireland rockers, locks, and cam.  For the setup, it might be best to call IE when you get some time.  There are a couple tips/tricks.

 

 

One thing that was a red flag to me seeing as how you had trouble removing the rocker shafts.  Did you have a machine shop check for warping?  Resurfacing done?  Valve guides checked?

[FB73tii]

+1 on giving IE a call. It is important not to torque the rocker locks too much. I cranked them down and they actually distorted the rocker shaft enough to cause the rockers to bind--not against the locks but on the shaft itself. You also want a little oil clearance gap. Andrew can give you the tips, including using locktite on the rocker lock bolts.

 

P.S: I slid the new camshaft into place and it seems to spin rather nicely... I'm hoping this indicates that the head is not too badly warped. I'm reusing the old rocker clips and washers on new rocker shafts- is this okay?

If you have any question at all about warping you should have a machine shop check the head for straightness. That said, I have had good heads that the rocker shafts were still tight on removal/install. A long brass drift is helpful for gently coaxing them in, or as posted here, a hardwood drum stick of the correct diameter (I think I used an oak 5A).

 

Yes, fine to re-use rocker C-clips, collars and thrust washers. Make sure you use the correct oil and procedure to break in the Schrick cam and rockers. High ZDDP oil (I used Joe Gibbs BR30), immediate start and hold revs at 2000-2500 rpm for 30 minutes. A bit of moly lube on the lobes is not a bad idea as well, critical if you are breaking in a high-lift cam such as a Schrick 316 or 336. If you don't know why, do a search on "breaking in a flat tappet camshaft." --FB

Edited January 8, 2014 by FB73tii

[2002inthewoods]

Thanks to all of you for the responses! - I will definitely be giving Andrew at IE a call tomorrow when I get a chance.

 

AceAndrew (any relation to the Andrew at IE by chance?) - No, I haven't had a machine shop check for straightness... I've driven by a place called Island Racing before which seems to be an engineering / engine building shop. I'll give them a call to see if they can do a check for me. I have not had any resurfacing done... and the valve guides have only been checked by means of just trying to see if I could gently wiggle the valves and notice any play (I didn't.. and judging by a couple of little things I noticed during disassembly I believe that the guides, valves, and piston rings had probably been changed at some point in the recent past) - I'm not sure if this is the ideal technique by any means though... As for the rocker shafts coming out - they were pretty seriously carbon/oil/grime covered. I think this was the reason for them giving such a fight. After cleaning out the holes for the shafts and using a new shaft... what kind of resistance should I normally be encountering? Right now a light tap from a mallet moves them along smoothly but its a snug fit.

[Hans]

There are several BMW specialists in VT. Kermit Upton comes to mind. May be easier to haul everything in there. Head reassembly is much easier with the frame that pushes down all valves at once. I'd get it checked for true-ness. That said, what was your compression. Your symptoms may point to rings too.

[FB73tii]

AceAndrew (any relation to the Andrew at IE by chance?)

One and the same. If Andrew is not available (new baby), ask for Jeremy. Both are very knowledgeable and helpful.

 

After cleaning out the holes for the shafts and using a new shaft... what kind of resistance should I normally be encountering? Right now a light tap from a mallet moves them along smoothly but its a snug fit.

Perfect!

[TobyB]

I disagree just a bit, Fred- in a new head, the rocker shafts slide with finger pressure. 

 

Several things happen that mess this up:

first, the heads warp.  Almost all of them, and it doesn't take much.  Like, a thou or two.

Second, the head bolts close down the rocker holes.  It "usually" doesn't happen at the factory, but I've taken

apart factory motors that had a bit of drag in one or more holes.  After a rebuild, it's pretty likely.

 

So 'a light tap with a mallet' is about right for most of us.

 

If I've got an unknown head on the bench, one of the first 'is it junk?' tests is to slide in a rocker shaft.

If it will go in 'easily' (without a 5lb hammer) I keep going.  A truly warped one often takes that hammer

to get the shafts out....  and when the shaft clears the center boss, sometimes you can see the misalignment.

 

splitting hairs,

t

[jgerock]

When I recently assembled the rockers on my 121 head, the new rocker shafts were snug but I could slip them in place by hand and then had to gently tap them with a rubber mallet when they got close to the other side.

 

I started from the front of the cylinder head and worked toward the back (distributor side).  Make sure to use a good quality assembly lube.

[FB73tii]

I disagree just a bit, Fred- in a new head, the rocker shafts slide with finger pressure.

 

Fine points appreciated. I have never had a new head to work with. I would think that higher torque used with ARP head studs might increase the issue of "closing down" the bore holes. So what to do then? Very light line hone? And if bores not aligned but want to save a head, can it be straightened by pressing, then surface milled for flat? --Fred

Edited January 9, 2014 by FB73tii

[2002inthewoods]

Make sure you use the correct oil and procedure to break in the Schrick cam and rockers. High ZDDP oil (I used Joe Gibbs BR30), immediate start and hold revs at 2000-2500 rpm for 30 minutes. A bit of moly lube on the lobes is not a bad idea as well, critical if you are breaking in a high-lift cam such as a Schrick 316 or 336.

 

Hmm... I have been using "Engine Assembly Lube" with moly-graphite along the way, and when I slid the IE292 cam into place I lubed up the journals and respective parts of the cam. Is this going to be alright? I can't imagine what kind of stresses and temperatures these components are going to be under when everything is back together and running, are there oil passages to keep the cam journals healthy? Are there other oil passages in the head that I should pay specific attention to? Perhaps blow compressed air through just to double check that they aren't restricted?
 - I didn't get a chance to call Andrew or Jeremy today, I will have to wait until tomorrow to reach one of them. 

[2002inthewoods]

Oh! I did take a second earlier today while I at the computer to post a short video that I took with my phone after installing the 32/36 carb, mech. dist, and exhaust system this summer. Just shows the rear end of the car so you can hear a couple of revs - but if anyone's bored and wants to check it out, let me know what you think!

 Thanks again for all the help guys.

[jgerock]

Hmm... I have been using "Engine Assembly Lube" with moly-graphite along the way, and when I slid the IE292 cam into place I lubed up the journals and respective parts of the cam. Is this going to be alright? I can't imagine what kind of stresses and temperatures these components are going to be under when everything is back together and running, are there oil passages to keep the cam journals healthy? Are there other oil passages in the head that I should pay specific attention to? Perhaps blow compressed air through just to double check that they aren't restricted?

 - I didn't get a chance to call Andrew or Jeremy today, I will have to wait until tomorrow to reach one of them. 

As Fred pointed out above in post # 4, when starting up a freshened engine, you must not let the engine idle for the first xx critical minutes of operation.  Notice I did not provide a figure since there are many opinions from engine builders and camshaft manufacturers.  Lots of internet reading to research.  When building my VW air cooled engine, my engine parts supplier (Gene Berg) cautioned me about proper break-in lubricant and RPM of the new engine, especially regarding the camshaft which would "flatten" the lobes if not properly done. To me, that is the most nervous part of building an engine  - the first start.

 

Unfortunately, the Schrick camshaft installation guide on their website does not say anything about break-in (nor does their catalog)

http://www.avl-schrick.com/dat/MK/Nockenwelleneinbau%20%20Camshaft%20Installation-berichtigt-25102005.pdf

 

I found a contact name on the website and sent an e-mail - will report back if they do...

Edited January 10, 2014 by jgerock

[FB73tii]

Hmm... I have been using "Engine Assembly Lube" with moly-graphite along the way, and when I slid the IE292 cam into place I lubed up the journals and respective parts of the cam. Is this going to be alright?

Yes, I use assembly lube (Lubriplate No. 105 white assembly grease) when installing a cam, on the journals and the lobes, as well as on the rocker shafts and rocker bores when putting them together. Some folks don't use assembly lube and just make sure to pre-lube the engine before starting by turning it over with the starter with the coil disconnected and the spark plugs out. That is good practice no matter what. My comment about moly paste (I use Sta-Lube EP engine assembly lube with moly-graphite) is that for extreme cams (not what you have), one must go further. The thick moly paste really sticks to the lobes. I read some internet stories about people using thinner "extreme pressure" (EP) lube and if the engine sat too long before startup (days, not weeks or months), the thin stuff would roll off the cam and they had issues.

 

Are there other oil passages in the head that I should pay specific attention to? Perhaps blow compressed air through just to double check that they aren't restricted?

Fortunately the M10 heads are simple and the oil passages straight. There are a number of them and all should be cleaned before re-installing the head. One key for good engine building is to have everything clean, clean, clean! Take a look inside the cam journal bores and you will see where the oil passages are. Swab or blow out any lint or grit that has gotten in there while it was apart.

 

As Fred pointed out above in post # 4, when starting up a freshened engine, you must not let the engine idle for the first xx critical minutes of operation. 

And the reason the engine should not idle is that the oil pressure will be too low at idle and will not properly lubricate the cam lobe/rocker pad interface during that critical break-in period. Even though a new cam and rocker pad look nice and smooth, if you looked at them with a microscope you would see that there is surface roughness. The two sliding surfaces need to work against each other for a while to get smoothed out and properly mated. For this reason, if you ever pull the head apart and put it back together with the same cam and rockers, you want to put each rocker back in the position it was previously.

 

The 2000 RPM for 30 minutes is Jeremy's suggestion to me for the Schrick 316. I varied RPM between 2000-2500 as the bottom end was new as well. You do have to be careful about overheating during the break-in period. Keep an eye on your temperature gauge. I could only do 20 minutes, then did another 10 after it cooled off. Next time I might put a fan in front of the radiator. Or just do it in the Winter

Edited January 10, 2014 by FB73tii

[TobyB]

Fred, I have cut an old rocker shaft with a cutting tip to ream out holes on particularly distorted heads that are otherwise ok...

 

t