Camshaft binding in head
 

Doing a top end rebuild on an '88 3.2.

After building the right side of the engine I installed the cam as per Wayne's book and notice that the cam drags a bit a certain point in the rotation. I try a few different torque patterns but still the slight dragging persists.

Bummed, I move on to the left side of the engine, but on this side the cam spins smoothly. Out of curiousity I put the left side cam in the right (dragging side) and it spins freely!

Do I have a bent cam, or something different? I had them done by camginder recently(964 grind), could something have happened in the reginding process?

Thanks for any suggestions/help.

You need to change the torque sequence. The bad news is you really should remove the cam tower and start over. As in remove the loctite, and reinstall. I did not do this - and now I have a little oil leak on the cam tower that I retorqued 12 hours later... bummer.

Mine was exactly the same - one cam tower, cam spun like a champ. the other cam tower and it bound up...

yeah - i did the same thing. Disassembled the whole thing and restarted it "nonstop" until it spins freely.

Thanks for the replies guys....

Don't you think it's strange that the cam from the "good" left side of the engine spun freely in the right "bad" side cam carrier?

I'm doubting myself now, but I'm pretty sure it spun freely. I guess if I try the "bad" right side cam in the left side and it still binds then I would be inclined to think it was the cam.

Am I off base on this?

BTW, did you guys use loctite 574 on the copper cylinder seals?

Thanks again....

Mine did the same, spun on one side - would not on the other. I did not use 574 on the copper cylinder seals - and wish I did now.

Put both cams on your bench next to each other. You will notice the 2 center bearings do not line up with each other. So, by installing the left cam in the right housing, the two center journals are not riding in the housing.
I straighten the camshafts to less than .0005" total indicated run out before I grind them. Unless they were damaged in shipping they will still be straight.

I would completely back off the housing and then insert the cam and check for binding. Should be fine.

Somtimes it is not the cam or the cam carrier's fault .
If you do any modifications in regard to the barrels or the head surfaces, to check assemble the heads on the barrels and install the cam carrier with a few of the 8 X 1.5 nuts, then torque the heads, afterwards remove the cam carrier and use a straight edge accross the heads.
If all is well apply your sealer and complete the fastening of the cam carrier, if not you can isolate the culprit.

regards

Quick question.

Obviously the loctite 574 has now cured. Can I safely loosen the cam carrier and try a re-torque without having the the assembly leak (assuming that I can get it to the point where the cam doesn't bind)?

Or at this point should I bite the bullet and tear the top end down, remove all the dried loctite, measure everything dry and refit?

Thanks again for all your help (camgrinder, racing97, etc...)

BTW, camgrinder, is there any quick and dirty check a can do with my cams to make sure they didn't get damaged in shipping?

That sucks.
You're right, now that the Loctite has dried you won't be able to get away with just retorquing.

Remove the cam carrier and clean the Loctite off both surfaces.
See if the heads are even using a machinist's straight edge or piece of ground stock. If can't do that, you can bolt the cam carrier on dry and see if your cam spins then.

Check the locating pin holes in the bottom of the cam carrier - make sure they haven't been "boogered" or plugged with sealant. Make sure there isn't any hardened Loctite "crumbs" anywhere between the sealing surfaces.

Whatever sealant you use (I use Threebond 1104 a.k.a. "yamabond") put it on thin.

This episode will be nothing compared to the pride you'll feel when you can say "Mine doesn't." the next time someone says "They all leak." (refering to 911's) .
-Chris

Heres a pic of the cam bearing journal locations. Other than removing the right side housing, you can put the right cam in the left housing backwards and the journals will all line up. That is if the soft plug at the end of the housing has not yet been installed.

http://drcamshafts.com/2/964.JPG

If you have access to a lathe and a dial indicator you can check the cam for bearing journal run out. Chuck up a dead center on one end and use the tail stock center on the back end. Set a magnetic base dial indicator on the toolholder and spin the cam by hand.

"If you have access to a lathe and a dial indicator you can check the cam for bearing journal run out. Chuck up a dead center on one end and use the tail stock center on the back end. Set a magnetic base dial indicator on the toolholder and spin the cam by hand."

Or support the cam on each bearing end with V-blocks, then measure with the dial indicator.

As racing97 pointed out, it could also be the component stack is not even between the 3 cylinders on the bank. The combined height of each crankcase spigot surface, cylinder base gasket, cylinder and cylinder head must be equal, otherwise the cam housing will tweek (or bend) slightly when the component stack is sandwiched.

Sherwood

Thanks everyone!

Seeing as how I put loctite 574 on the copper cylinder base gaskets, can I leave the cylinder heads torqued down and just remove the cam carrier, clean up the surfaces and try to re-fit?

Yes. Permatex Gasker Remover spray works well on removing old 574. I don't know if it's necessary but I'd mask off the springs in the head with some aluminum foil before spraying the remover.
-Chris

Hello there.

I do not think 574 should be used at the cylinder base..it hardens, and if the whole assembly is not torqued very quickly, it will form an incompressible wedge.

Furthermore, there is a lot of movement here with heating cooling cycles...

I use blue Hylomar with no problems..its soft and stays that way.. you can replace stuff without cleaning it all off in a pinch..use it all the time on gearboxes etc which have to come apart in the field..(literally).

Kind regards
David

It's distinctly possible that you've just identified your problem.

See this thread

Well, removed the cam carrier. Cleaned off all the loctite 574 (thanks Chris for the recomendation of the Permatex, worked like a charm!). Cleaned off the heads as well and took Chris's recommendation of covering the valves springs with aluminum foil. It wasn't very fun....

Now I put the carrier on dry, bolted it down and.... still no luck. The cam continues to drag at a certain point in the rotation.

Now what the hell do I do? Where whould you get a machinists straight edge? Will that tell me anything I don't already know? Should I remove the heads, pull off the pistons and cylinders, clean the loctite from the copper gaskets, and then reassemble dry. Is there a way to deffinitively measure what's wrong? Is it possible to send the parts off to someone to measure and correct, since I don't trust myself to measure it with any precision.

Btw, I had the heads decked by Walt at Competition. I know he does great work, but could it be possible that something didn't go right?

Any suggestions?

Thanks....

Just a thought - have you tried the cam in the carrier with the carrier on the bench?
JB

I 2nd Jims Idea. back off the bolts and see if the cam spins. There could be a nick somewhere in the carrier or on the cam causing the problem.

As others have said you should remove the 574 from the base gaskets. If it hardened before you finished torquing the heads it will be different thicknesses under the cylinders. Also with the shifting around and pounding this area takes it may crack and start to leak. A non hardening sealant is what to use here.

As far as the drag goes, my opinion is that if it's a minor drag that you can easily turn through by hand then it won't be a problem. Think about how much the cam is pushed sideways by the valve springs when the engine is running. The slight drag you are feeling will be much less force on the bearing surfaces. These surfaces are pressure lubed and can take lots of pressure. I know this goes against conventional wisdom but sometimes conventional wisdom is wrong.

-Andy

I've been watching this thread, thinking that it was something obvious that would have been figured out by now.

Okay, if you still have the problem after doing all that, you need to start at the source:

- Measure the cylinder mounting surfaces with respect to each other. The 3.2 aluminum cases usually don't warp in this area (the 2.7s do), but you never know

- Measure the shims under the cylinders. Don't truse the manufacturers - measure everything.

- Measure the head surfaces and distances between them.

- Measure the cylinder heights.

- Swap the left and right cam towers and see what happens. If the camshaft still gets stuck, then you know the problem is with the left cam tower...

-Wayne

Swap left and right cam towers before you do anything else, and let us know how that works...

-Wayne

I would also check the cylinder to cam tower joint for uneven drying. If you applied 574 here a thick coat can also dry unevenly causing the loads on the cam tower to be inconsistent.


Waynes advise also seems spot on.

So, first off, thanks everyone for all the advice.

Here's what I'm going to do. I've already pulled off the right hand pistons and cylinders. The loctite did appear to be unevenly distributed around the base of the cylinders, but maybe this is just me hoping.

I plan to clean all that stuff off, measure the shims and cylinders as best as I can. Then I'm going to dry fit everything and see what happens. If everything is ok then I can only assume the loctite hardened before I could torque everything down. For the rebuild I'll probably use Curil-T instead for the base gaskets.

I'll let you know how things go.

BTW, I don't think I'm going to swap left and right cam carriers because the left side of the engine bolted together fine and the cam spins smoothly on that side. I don't really want to mess with something that seems to be ok.

Also, how do you measure the head surfaces and distances between them with only a vernier caliper and dial indcator?

Okay, I can understand that. Then, I would maybe borrow a cam tower from someone and see if it fits and the camshaft spins freely - I'd hate to see something wrong with your cam tower, and you have to tweak it to get it to work properly. Don't forget that everything changes when these engines heat up, so you want to make sure that things are perfect when they are cold. On that thought too - the camshaft may spin freely when the engine is hot - you'll never really be able to tell. Still, I would personally feel more comfortable trying out another housing...

-Wayne

Does the cam spin free in the housing when its off the engine?

Is the cam straight? I don't see a confirmation of this or did we just move along to step 6?

Sherwood

To answer some of the outstanding questions...

Yes the cam spins freely when off the engine.
On a side note off the engine, I was spinning the cam by hand and if I listened very closely you could hear the faintest (and I mean very faint) sound of drag when spinning the cam happening at the same position it did when torqued down. Whatever this is may be exaserbated when it gets torqued down unevenly. Again this was extreamly faint and couldn't be felt with the hand when rotating it. So it may have a certain amount of runout but shouldn't be a problem in a normal situation (meaning the carrier not being tweaked after torquing).

I haven't measured the cam. I don't have a shop and so thought of making some v-blocks out of hard wood and measuring that way. I would assume that would work. Actually I just recalled that Elgin(the cam maker is 5 min from my house). They might be kind enough to measure the runout on the cam for me.

It would be nice to have access to a know straight carrier that I could bolt on, but alas I haven't seen any lying around my house. :) I'll have to see if anyone local can measure the flatness of my cam carrier. I'd like to be able to eliminate that once and for all.

Thanks again for everyone's help on this.....

The V-blocks must be machined metal for trueness. Pay Elgin a visit and ask them to check the cams, then you can move forward.

Sherwood

Got the cam measured at Elgin.

They said it was in spec. One of the journals was just slightly out (still in spec) and they cleaned it up, but I don't think the cam was the problem.

So, off come the pistons and cylinders. I've scrapped off most of the loctite. Let me tell, that's not been fun. Once that's done, I'm going to put everything together dry and see what happens.

One interesting thing I found out. It looks like John Dougherty(camginder) worked for Elgin for 15 years and they didn't seem to happy to see me bringing in that cam. They measured it for free though, so that was nice.

Thats too cool.

He He............. :)

Cheers

Status Update....

Assembled the right side of the engine dry and ......

Still having a little binding with the cam. Loosened the 4 cylinder head bolts from the middle cylinder (#5) and the binding went away. So, either my cam carrier is warped/not flat or my cylinder+head height is wrong. Anyone know of a place in the bay area (San Francisco) that can measure my carrier for straightness?

Any one have any other suggestions?

I'm pretty sure Ted from German Precision in Sunnyvale can narrow down the problem for you...

JB

You can get a piece of ground stock and use that for a straight edge.
I use something like this http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=1750523&PMT4NO=2509883 from MSC.
You can use it when you measure your sprocket parallelism too.
-Chris

As others mentioned uneven cylinder heights will do this.

Did you measure your base gaskets? Are you SURE your cylinders are the same heights?

You could have have mixed a single cyinder from left to right and one side group was shorter or taller. WHen you torqued the head down, you warped the cam carrier. Every time you retorque it, it'll get a bit worse.

Did you have your heads or cylinders machined?

Searched and only found 2 threads on this problem but I'm in the same boat. On the driver's side if I loosen the head studs on #2 the cam spins fine (spins when just put in the cam free as well, right side seems fine) The only thing I've had done was send the heads to Walt at CE for rebuilding. I marked all of them, along with the cylinders, so everything would go back in the same spot but when I got the heads back the marks were gone on all but 2 heads, and it's not very clear on those two. I know cylinders have height groups but can't find anything in Wayne's book or Bentley to indicate that heads are grouped in size. Nothing was indicated in the paperwork with regard to cutting of the heads but i emailed Walt and he said he'd cut .25 off so I went with 2 .25 gaskets. This all tells me the #2 head/cylinder assembly is just a bit "shorter" than 1 and 3...correct? I plan to remove the heads and try to measure how much shorter then add another shim...does this sound like the right solution? Not sure I really have any other choice. I did try retorquing but the heads bind up even with the 1st low level torque, regardless of pattern. Pretty frustrating...

Can you swap the heads and try them on the other side? You have one good side right?

Yes, the "right" side spins fine. I'm reluctant to pull it since it's working fine but it may be that I have to mix n' match to get them both spinning smoothly. I do know that before I removed the cams they both spun fine in the cam towers and neither the towers or cams were altered since they look to be in perfect condition. I really wish I knew which heads came of which cylinders but that's a moot point now...the marks are gone. Do heads get grouped into sizes like cylinders? If I do end up with one head slightly shorter than the other 5 due to the cutting I can just add a spacer, correct?
Also, I assume torquing #2 at a lower level is not an option correct? I'm not even sure that would work. The only option is the torque SEQUENCE, right, not the torque value?
Starting to regret taking this on...really had no choice though.

The heads are not grouped, Sounds like the only thing that changed was cutting the sealing surface on the heads, if one is off it will make it bind, if you can get a 3-4 inch mic you can check the heads for sameness.

Thanks Craig, that looks like my best option, at least I'll know one way or the other. Dumb of me to assume they'd come back the same but I was thinking if they removed the same amount of material off all 6 then they'd be okay. I did do a dry test fit but did not torque the head studs all the way...looks like that was a mistake too. Nothing like going back a week in the process! LOL!
Thanks for the suggestions,