With the piston and cylinder job behind you, and your engine turning over nicely, it is time to install your cylinder heads and cam boxes.
Your restored cylinder heads should be ready to plop on, but if you have not rebuilt them, check out our eight-part series. As well, now is the time to take a cylinder head volume reading if you have changed any part of the heads! The engine math is not complicated if you work through it step by step.
On this 2-Liter 911T engine, we are using stock head studs. If you are using the updated 993 studs, (on the exhaust side and or the intake side), you will have worked through any fitment issues already. The heads will slide on just fine with the set-up we have.
The first thing to do is remove the hold-down nuts and install the head gaskets. On this engine, they are composite head gaskets. And care needs to be taken to work the gaskets down in place.
Now is the time to lubricate the cylinder head studs with copper grease. Drop each head over the studs till they seat. Cylinder head stud washers come next. The trick to installing the head stud washers is to use a screwdriver. With the screwdriver placed on the stud, then drop the washer. This little trick will make your life a lot easier!
Chemicals you need for the job.
When we put on the cylinder head nuts we do not tighten them all the way. We want to let the cam box have some wiggle room to the heads for the best fit. The heads must lock into the dowle pins on the cam-box.
Clean up any oil or grease on the sealing surfaces of the heads. Before you put any sealant on the cam box, you need to install the one piece oil return tubes. The oil-return tubes are sealed into the case and cam box with a big silicone O-ring. Again, as we have said many times, no sealant required here, just a good amount of silicone lubricant.
In the cam boxes, there is an oil feed line for the cams. This line is the end of the oil system and if you have not gone through your cam box, we have a lesson on that too! You may not need to remove the tube every time, but you sure need to clean it out!
Apply the 574 sealant onto the contact surfaces of the cam box. Get around all of the bolt holes as oil can travel up the threads. Spread out the 574, remember you are on a time limit when the 574 touches the metal.
Gently work the cam box down, using a plastic hammer to set onto the dowel pins if necessary. At the same time as the oil return tubes go in as well. 8mm-Wave washers and nuts go on next and we work them down from the center out.
We are going to torque these 8mm nuts to 25Newton Meters. Remember there are three barrel nuts too.
Torquing the Cylinder heads.
Now the cam box is torqued to the cylinder heads it is time to torque the cylinder heads to the case.
The final torque is 35 Newton Meters. We will do this in two stages, first to 25 then to 35. Work your way from the center out.
Chain Box Housings
Now the heads and cam boxes are on you can go ahead and install the cam chain housings. There is a gasket at the base and studs and locator pins in place on your engine block. Torque these 8mm nut to 25 NM.
Up Next, Camshafts and Timing
The cam timing is not a hard job if you set up things correctly and have the correct tools. The lesson will start with lining up the cam chains with the intermediate gears.
2 thoughts on “How to install the Cylinder Heads and Cam Boxes on your Air-Cooled Porsche”
Do you have a preference when it comes to chain box gaskets? Green vs grey graphite like gasket?
Also, I see a lot of paper gaskets where mechanics have coated them with 574…trans gaskets, chain box gaskets, etc. Is there any benefit assuming the surfaces are good?
The chain box gasket is an area where there are a lot of factors to consider. Firstly the grey graphite gaskets are the Porsche superseded ones that are supposed to be the best to use. They are designed to be installed dry without any sealer. When building a 3.0L aluminum motor and on this is not an issue, however with the magnesium engines they are other factors to consider. Most magnesium engines are showing signs of surface pitting and warpage across the sealing area. What we are doing here is resurfacing both the chain box and the engine case surfaces. The next issue is that the material removed now has to be made up so that the chain box will correctly align with the cam box.
what I will do is make a new gasket using a gasket paper thickness that matches the amount of material removed plus the original gasket thickness. When it comes to using a gasket sealer it is always a patch, as the gasket is supposed to be the seal. But I also understand that sometimes it has to be done when doing a repair versus restoration. What you have to consider is that it will add a degree of increased cleaning the next time that anyone goes into the same area again as now the old sealant will need to be cleaned off. In a perfect world, the surface should be corrected then the gasket applied to the clean and dry surface.
What I do see a lot is mechanics that apply a sealant to everything. This is not a good practice at all and should not be done. If the surface is clean and flat then only the gasket is required. O-rings and oil seals should never have a sealant applied, just lubricate them with either engine oil or silicone grease and install. If you need to use a gasket helper then the only one I would use is the 574, never use silicone or any kind of curing liquid gasket. This can result in more damage occurring due to contamination.
Comments are closed.