Installing heads with cam tower

[worn]

I needed to split the case on my 911sc and replace the left cam shaft. I pulled the right side heads and cam tower all as a single unit. Do I have to separate heads from cams to reinstall, or can I put it back as one piece?
Thanks!

[Flat6pac]

It goes Back as one piece Without the chain box but be sure you don’t have any pistons at TDC because there are valves open. I move the TDC back about 30 degrees so all pistons are down.
Bruce

[Iciclehead]

Originally Posted by Flat6pac

It goes Back as one piece Without the chain box but be sure you don’t have any pistons at TDC because there are valves open. I move the TDC back about 30 degrees so all pistons are down.
Bruce

Bruce, is that your preferred method of reassembly or is it just in the OP's specific case?

I have always wondered about the logic....heads to cylinders followed by cam towers or cam towers on heads and then the single assembly to the cylinders.

I can see advantages and disadvantages both ways.....just wondering about what your considerable experience has taught you..

Thanks

Dennis

[Flat6pac]

Dennis and all
Yes, I build up the sub assemblies such as a head, cam carrier, cam and rockers and set valve lash on the table
Build up the crank on the crank stand, load the pump and chains into the case half
Sub assemble the P&Cs complete with wrist pins sitting out
Then assembly is units and easily assembled.

[Iciclehead]

Originally Posted by Flat6pac

Dennis and all
Yes, I build up the sub assemblies such as a head, cam carrier, cam and rockers and set valve lash on the table
Build up the crank on the crank stand, load the pump and chains into the case half
Sub assemble the P&Cs complete with wrist pins sitting out
Then assembly is units and easily assembled.

Good enough for me....and makes sense to boot.

I like the idea of being able to scrutinize sub-assemblies, along with the necessary trial fits and measurements as opposed to maneuvering around a big honking engine on a stand deal.

Thank you for your insight...it helps us amateurs mightily.

Dennis

[Lyndon302]

May I ask
574 loctite for the towers and torqued to spec. Then then heads torqued on the barrels. Any need to loosen the cam tower during the cyl head torque sequence.( sealing issues with the 574 ?? )
Also a quick explanation on how you then fit the chains when the engine is 30 degrees out ready for cam to timing ( piston to valve issues )
I am at this stage. On my build.
Many thanks Lyndon

[Flat6pac]

I have never had to loosen cam carriers during build.
With the pistons in the barrels, the heads on, turn cams to the key way up the bring the crank up to Z1. Everything is close enough to assemble the chain drives on cams.
Bruce

[worn]

Thanks folks. Here I go.

[Lyndon302]

Great info.
Here in Australia I can't get Curil T. What would be best for the base copper gaskets for the barrels??
Lyndon

[Flat6pac]

Generally, sealant isn’t needed on the base gaskets but I have used 574 if I were using more than one or if there was leakage on the bases of cylinders before I took it apart.
Bruce

['78 SC]

I started installing heads and cam towers together a few rebuilds ago (taking Bruce and John Walker's) advice. I find it more convenient to build up and adjust the valve train working at the bench (plus there's no risk of dropping something into the assembled shortblock). Some comments/observations/suggestions:

• If you want to check for cam binding, you'll have to do a trial fit on the cylinders before installing and adjusting the rockers.
  
• When setting the valve clearances without the aid of the crankshaft pulley markings, make sure the cam is properly rotated/oriented and the rockers are on the cam base circle. Cam rotation is CCW.
  
• The assembly is heavy. I generally work alone, so I use a chain hoist to ease it into place so I can guide it onto the studs and oil return tubes
  
• When installing, pay attention to how everything is clocked. I put the crank at TDC and both cams with the "dots up". This may not be the only right way, but there are a lot of wrong ways. Double check this before torquing head studs.
  
• I slip the chain boxes over the cams and guide them onto the mounting studs as the heads come in for a landing. Maybe they can be installed afterward, but I find this easier.
  
• Remember to install oil return tubes and cylinder airflow deflectors as soon as the cylinders are installed and before building up the heads (don't ask how I know ).

[Iciclehead]

Originally Posted by '78 SC

I started installing heads and cam towers together a few rebuilds ago (taking Bruce and John Walker's) advice. I find it more convenient to build up and adjust the valve train working at the bench (plus there's no risk of dropping something into the assembled shortblock). Some comments/observations/suggestions:

• If you want to check for cam binding, you'll have to do a trial fit on the cylinders before installing and adjusting the rockers.
  
• When setting the valve clearances without the aid of the crankshaft pulley markings, make sure the cam is properly rotated/oriented and the rockers are on the cam base circle. Cam rotation is CCW.
  
• The assembly is heavy. I generally work alone, so I use a chain hoist to ease it into place so I can guide it onto the studs and oil return tubes
  
• When installing, pay attention to how everything is clocked. I put the crank at TDC and both cams with the "dots up". This may not be the only right way, but there are a lot of wrong ways. Double check this before torquing head studs.
  
• I slip the chain boxes over the cams and guide them onto the mounting studs as the heads come in for a landing. Maybe they can be installed afterward, but I find this easier.
  
• Remember to install oil return tubes and cylinder airflow deflectors as soon as the cylinders are installed and before building up the heads (don't ask how I know ).

....words to live by, sounds great and very helpful!

Dennis

[Lyndon302]

The trial fit to check for cam bind. When you torque the heads down. Do you use the old head and base gaskets. ??? I take it you don't reuse new ones after the trial fit ?
Then pull apart. Fit pistons and new gaskets top and bottom and reinstall with rockers set.
Lyndon

[Walt Fricke]

'78 - +1 on being lucky to be able to use a chain hoist to lift the assembly. I did that the one time I used this method. But if your arm strength isn't what it once was, the more traditional method is more appealing to me anyway. I'm not on the clock, so to speak - I don't like to dawdle or be inefficient, but that only affects my free time.

I always have at least three collapsible oil return tubes on hand (they are reusable and durable). In practice, I plan to use one for the tube closest to the scavenge oil fitting. You know why I have the others, though through pure luck I've not had the deflector dilemma.

['78 SC]

Originally Posted by Lyndon302

The trial fit to check for cam bind. When you torque the heads down. Do you use the old head and base gaskets. ??? ...
Lyndon

IMHO...
I would leave out the cylinder-to-head gasket since it doesn't affect the stack height (and it gets compressed when installed), but I would install the fresh copper base gasket. I would re-use that base gasket for the final build - it is durable (has to be, to do its job) and I doubt being installed a couple of hours at room temp is going to deform it. I do, as a matter of course, run some Hylomar or Curil T at the junctions of the case/gasket/cylinder to keep things dry.

['78 SC]

Originally Posted by Walt Fricke

'78 - +1 on being lucky to be able to use a chain hoist to lift the assembly. I did that the one time I used this method. But if your arm strength isn't what it once was, the more traditional method is more appealing to me anyway. I'm not on the clock, so to speak - I don't like to dawdle or be inefficient, but that only affects my free time.

I like to think I'm getting smarter, not weaker.

All my rebuilds take months, so I certainly can't promote this as a time saver. I do like working at the bench for the fiddly stuff like rocker installation and setting valve clearance. And the absence of panic when I drop an aluminum washer.

Ready to receive the heads. Note the gaskets in place as memory aid.


Ready to lift head assembly.


Chain hoist is on a trolley that runs in a stick of Unstrut. I also use this to move the engine between a lift table and the engine stand and to move the transmission between the engine, stand and worktable.

[Walt Fricke]

A little overkill on that balancing beam, perhaps?

I built a hanging platform using that electrical positioning beam stuff - 3/4" plywood slots nicely in - so it has pretty decent resistance to bending. Hadn't thought of it for a track. Are the hangers lag bolted to the ceiling joists? Strong enough to hoist the engine/tranny?

When I built my garage I had no inkling that the I beam could be put to other uses.




On seeing my picture I think I used the unit system because I was doing trial fitting and clay

['78 SC]

Originally Posted by Walt Fricke

A little overkill on that balancing beam, perhaps?

Maybe, but it's a Harbor Freight special so "too much is never enough"?

I originally used a length of 2x4 as a spreader to keep the chain from pressing against the fan housing, but didn't like the risk of it popping out (plus it was a bit too "shade tree").

Originally Posted by Walt Fricke

I built a hanging platform using that electrical positioning beam stuff - 3/4" plywood slots nicely in - so it has pretty decent resistance to bending. Hadn't thought of it for a track. Are the hangers lag bolted to the ceiling joists? Strong enough to hoist the engine/tranny?

I would have preferred double-deep Unistrut. If I could weld I would put two sticks together back to back for more stiffness. The trolley (the part that rolls) is rated for an honest (not HF ratings) 600 lbs. The trolley and hangers are from McMaster.-Carr and designed for this kind of use. The space above the garage is engineered for occupancy - 2x12 joists on 16" centers with tongue and groove subflooring to stabilize them. Prior to installing the Unistrut I had the hoist hung between two of the 2x12s and found that easily supported the engine weight.

The only time I roll the trolley is to move the transmission or heads around. When transferring the motor between the stand and hydraulic table I just dead lift the motor and swap the stand/table under it.

I'm glad you brought up the topic of strength. I wouldn't want someone to hang a chain hoist on a too-weak structure and have something go wrong.

BTW, nice I-beam and trolley.

[Walt Fricke]

I don't have (or didn't make) room for a hydraulic table or the like, so the I beam has proven super helpful moving engines and transmissions as the need arises. Old climbing ropes and a Jumar (one way rope clamp) put to good use as the beam slopes.

I got the Unistrut at HD while looking around, but didn't realize it had structural uses per se, and was more than just a convenient track to position holders of pipes and conduit.

The steel verticals which suspend my storage platforms from my flat roofed garage ceiling are bolted horizontally through the 2x10 joists. Ceiling drywall came later. I didn't know just what the load bearing capacity of vertical lag bolts in 1.5" wood might be, though perhaps pretty significant? Overkill for static structures probably not a bad thing in the face of uncertainty/ignorance?

Sounds like lift tables are probably the most practical for most of us shade treers, who adapt to our garages rather than purpose building them.

[JJ 911SC]

I use a small hydraulic lift table to get it close enough and took a big breath before lifting and sliding them on the studs