camshaft housing fit against heads

[Baby]

I'm installing the heads on a 3.0 and per Bentley temporarily installing the camshaft housing to align the heads before torquing them. Then I will remove the housing, apply sealant, and install that.

I assume with some jiggling of the heads the alignment pins in the heads should fully insert into the holes in the housing and the mating surfaces should mate prior to my installing the nuts that hold the housing to the heads and tightening them down. Should this be an easy fit? Mine seem to almost want to fit, but I can't get the housing less than 1/4 inch to the heads.

[faverymi]

Be sure pin and pin holes are completely clean. Nothing on them.

[Flat6pac]

Its really easier to assemble the heads, sealant and cam carrier on the table and then install on the engine.
I also install the cam and rockers pryor to installing the head assembly.
Installing the heads first makes it difficult to hit the 24 studs and pins all at one time, If you leave the heads loose to move slightly it might work better but then youre doing extra steps without moving forward on the assembly.
Bruce

[Flat6pac]

[Smoove1010]

I've been pondering this same issue, since I'll be facing this shortly. It seems like there are numerous ways to get this done. There's the assemble heads/tower-as-a-unit approach described by Bruce;

There's the method you tried, where you install the cam tower temporarily to align the pins, heads, and tower, which is also used in this youtube clip:
Nick Fulljames fits barrel & cam carrier.wmv - YouTube

Wayne's book describes installing the heads finger-tight, then fully installing and sealing the cam housing on the finger-tight heads, then torque the heads down fully, which is a sort-of hybrid of the two approaches.

I'm inclined to follow Wayne's approach, but I'd love to see more opinions on this from those who've BTDT.

GK

[Baby]

Thanks for the input. The pins are spotless. Bruce, when the first housing didn't go on easily, I tried to assemble the other housing and heads on the table. I couldn't get the pins of even one head to go in all the way.

I went back to the block and was able to get that housing to seat by putting barrel nuts on the corners and tightening them evenly. Didn't take much pressure at all, and I was comfortable that I wasn't mashing anything.

Getting the housing off then required some firm taps with a rubber mallet, and I remember when disassembling they were tough to get off.

My problem with Wayne's method is the rush required to get the entire job done before the sealant begins to harden. Not the best recommendation for a first-timer like me.

[timmy2]

I did mine Wayne's way.
I just made sure I had all my tightening torques and sequences laid out along with the required tools and was done in no time.
The anerobic sealant won't harden that fast.

[Nostril Cheese]

Assemble the heads, sealant and cam housings first, then put them on the cylinders. The other way is just more work.

[Flat6pac]

I seal heads to cam carriers with Avation Permatex.
Recommended 30 years ago and still sealing...
Bruce

[Walt Fricke]

One reason I don't usually install cam carriers to heads on the bench is the weight of the assembly. Though if I need to pull a head to inspect something inside, and expect to be able to put the assembly right back on, I can use my chain hoist, which slides on a girder conveniently located over my bench engine stand.

[Baby]

For what it's worth, I did the other side on the bench. Still had to use nuts to seat the housing. Hand tightened hardware, carried to block and mounted to cylinders. Only marginally easier than the Wayne method, but I'll probably do it this way next time, too. Thanks again all for your insight.

[KTL]

Originally Posted by Flat6pac

I seal heads to cam carriers with Avation Permatex.
Recommended 30 years ago and still sealing...
Bruce

Bruce,

Is the best method of using the AP to put it on as thin as possible? I found that any excess will bleed/run when the engine heats up. I do like the AP because of its availability and ease of cleanup. Just a bit touchy trying to ensure you get enough sealant on there to seal, but not too much that causes ooze/push-out and then bleeds when warmed up.

Thanks,
Kevin


I'll add that its not uncommon for the heads to be a "press" fit on the cam housing. Those dowel pins are a tight fit and the heads don't simply plop down into place. Rubber mallet is my install & removal tool for cam housings.

[Walt Fricke]

Rubber hammer (now one of the dead blow variety) is my friend also for cam carrier installation.

However, for separation of carrier from heads (while heads still installed) I use an air hammer with a blunt end tool I fabricated (welded a big washer on the end of some air tool piece I modified a bit). Yes, the cam carriers show some denting in the spots (which I think are cast into these pieces for the purpose of allowing upward force to be applied) I use, but it helps a lot. And the denting has no functional effect - and you'd have to look awfully closely on an installed motor to detect if.

I have also found that if I attach the carrier to the chain hoist I have directly above the engine on the stand, and crank on it a bit, I have magnified the effect of each upward blow, and minimized the rocker effect (push one side up, other side goes down).

[swade]

Just installed my cam housings today. Head stud nuts loose, this allows the heads to move. Even hand tight keep the heads from adjusting to the cam housings. When the head studs are loose the cam housings slip on very easy.

[roadster49]

I have assembled my heads as a unit as described by Bruce. Some of my valves are open and I am concerned they will hit the pistons when I synch the cam and the crank with the chains.

How do you know the position of the crank relative to the cams without the chains?

[K Sykes]

Roadster49, Search "cam timing".

But more importantly, don't install camshaft and rockers until heads, cam tower and chain box are on. And you only need one rocker/side to time the cams.

[KTL]

When the cams are installed with the "930" or punch marks up, 12 o'clock, vertical, the cams are set in a good interim position to avoid valve contact.

[lindy 911]

Also, once the cams are set to the interim position, make sure the crank is rotated to have the Z-1 mark line up with the case split. This puts the #1 piston at top dead center and times the crank to the cams. Important if you're trying to not hit valves with piston tops.

[Trophy]

When you bolt the heads to the cam housing in this manner, is this all torqued to final spec at this point?

[KTL]

Yep the torque spec for the heads to the cam housing is only 18 ft-lb/24 Nm. So there's no reason not to torque the heads on the cam housing IMO. The heads are not going to move at all when you set the head & cam housing assembly onto the cylinders anyway, even if you just lightly snugged the heads, because the heads are dowel-pinned onto the cam housing at each head location.