Head install sequence

[neilca]

I have been debating with myself and need some input. The last time I installed my heads I first attached them to the cam tower and installed the three heads at the same time. I was reading Wayne's book and he says to install the heads individually and then attach the cam tower. I have pro's and con's of both methods. What does the board say?

[Flat6pac]

If youre trying to hit the 18 studs on the heads that are torqued..good luck
I worked in the auto industry for 30 years and sub-assembly is the way. I do the heads, cam carrier, cam, rockers, and adjust the valve lash on the table. When I install on the engine, as I m lowering the unit to the cylinders, I slip on the chain box.
The thing to watch for is the green oil return tube seals, if theyre not lubed well, they can pinch and cause an oil leak.
Bruce

[neilca]

That is why I did it fully assembled the first time. I didn't think you would have much luck aligning those pins after the fact. BUT I can also see where the heads may not get fully seated correctly as influenced by the other two. Perhaps install the heads, check the alignment with the cam tower then torque them once you feel they are aligned?

[Smoove1010]

Originally Posted by neilca

Perhaps install the heads, check the alignment with the cam tower then torque them once you feel they are aligned?

I took this approach on mine. In effect, you're using the cam tower as a jig to register the position of the heads. Since you're not bolting the cam tower in place, you're not impeding the torquing of each head individually. Worked perfectly for me, but I've got a grand total of one 3.2 top end job to my credit.

Here's an informative sequence on this job. Watching this and hearing his rationale convinced me to take this approach: Nick Fulljames fits cam housing & talks ramps.wmv - YouTube

[neilca]

Thanks for the link. That is what I will do.

[whiz05403]

Originally Posted by Smoove1010

I took this approach on mine. In effect, you're using the cam tower as a jig to register the position of the heads. Since you're not bolting the cam tower in place, you're not impeding the torquing of each head individually. Worked perfectly for me, but I've got a grand total of one 3.2 top end job to my credit.

Here's an informative sequence on this job. Watching this and hearing his rationale convinced me to take this approach: Nick Fulljames fits cam housing & talks ramps.wmv - YouTube

Watching Nick on the video, I was surprised to see how little Loctite 574 he used. I believe Wayne's book mentions to bush on the sealant. Nick just makes a small bead and then puts on the cam tower.

What have you guy been doing?

[dmark9]

For the 964, I was told to bolt the cam tower to the heads first then torque the heads to factory specs. Then remove the cam towers, apply loctite and torque to spec. This worked great.

Case Sealant....I did it both ways and the second time I did what Nick Fulljames did. The engine is still dry after 5K miles. You want to lay a bead around the INNER perimeter of the case so the sealant does not get close to the studs. I think my website has glimpse of this in a preview.

Good Luck and feel free to reach out to me with questions at P Fix It | Porsche 964 | Repair & Maintenance Videos

[Walt Fricke]

I've used the small bead of sealant around the openings (and looping around the outside of each stud hole) with success. First did it when I couldn't find the miniature paint roller I had previously used. Not sure if it saves time, as one likes to be careful applying the bead, but it works fine as far as sealing goes.

I know guys who are good at this, like Bruce, like to install the heads as a unit of three under the carrier. I find the assembly is a bit heavier than I want to deal with. So I've always installed the heads with minimal torque on the stud nuts, which allows self-alignment as needed (I watch the spacing between heads to eyeball it to parallel). Then the cam carriers and torqued their many nuts. Then inserted the cam, and torqued the heads to spec, rotating the cam periodically. If it binds at all when you are done torqueing (a little bind along the way I have come to think of as normal, because you suck the middle down first), I loosen the nuts and start over, which to date has always removed any slight bind. I don't see how you can do this installing on a bench.

When I started doing my own motors there was no sequence for torqueing any of this. Clymer didn't have it, and neither did the factory workshop manual. This was a surprise, because the VW books all showed you a pattern. So I kind of winged it. Then Wayne came up with a pattern for the carrier, and one for the heads. Don't know where he got it, but I now flip open his book each time and follow it.

[silver911rdb]

So what do you do when the cam is binding after you torque the nuts to spec? I have the cam tower bolted to the 3 heads and torqued in the correct sequence. When I go to torque the last few fasteners the cam binds. It's the bearing journal closest to the front of the engine that binds. I can feel the cam start to bind as I torque to final spec. I tried different sequence with similar results.

[Lapkritis]

Are the heads torqued down or loose when you're experiencing the binding? Did you try swapping with the other cam tower (assuming that one didn't bind) onto the offending cylinders? This will tell you if the problem is a cam tower issue or not... perhaps then head fly cut unevenly, jug height difference or spigot surface height difference.

[silver911rdb]

I tried it both ways...but initially I had the heads loose. Good idea on swapping cam towers. I'll try that tomorrow.

Thanks

[whiz05403]

Did you torque down the heads first and then set a straight edge on them and make sure they were dead level with each other?

any non-levelness will subject the cam tower to bend slightly jamming up your cams.

FWIW, my cams tightened up slightly after I torqued everything down. I could still turn them by hand, but they definitely tightened up.

[silver911rdb]

I torqued the tower first then the heads. I then went to put the cams in and I couldn't pass through the 1st journal. I then loosened the tower nuts and the cam went in easily. I torqued the tower again and same thing. So I thought the same thing about the heads being uneven, so I loosened the heads and redid the tower. Same thing. So I'm pretty sure the height of the heads and cylinders isn't causing the bend.

[silver911rdb]

Found the problem. Took everything apart and found there was a nick on the cam tower mating surface. I stoned it flat and everything is good now. It was a real small nick but it made a big difference in the way the cam felt. Thanks!

[Lapkritis]

Good to hear!