912 Head Nut Washers

[ironhorse]

I bought a '68 Type 616 (912) motor several years ago. The seller claimed that it had been rebuilt, but never ran it.

When I examined it, I noticed the builder didn't install the air defector plates under the cylinders, so I needed to remove the heads to install them. When I removed the muffler and cooling tins, I noticed the left-bank cylinder head (cyls #3/#4) had a cracked cooling fin, some erosion at the face of cyl #4's exhaust port as well as two cracked exhaust stud bosses. I had EMW repair all of the problems, but just now getting back to the project.

A couple of weeks ago I installed the head and started the tightening process. One of the internal head nuts (far right one) didn't want to fully seat and had a visible gap. I removed the head again and chased the threads on the stud. The nut still didn't want to thread down all the way, so tried I the other 3 nuts - with the same result

I grabbed my tech book and read the head installation procedures again. That's when I realized the builder forgot to install the rubber O-rings for the internal head nuts too. It looks like he applied some sort of sealant around the nuts after tightening them. I didn't check to see if they were torqued to spec. Assuming the other bank was probably missing these parts too, I ordered 16 head washers and 8 O-rings (as well as new intake & exhaust gaskets, etc.).

Today I oiled and installed the new O-rings, then I dug out a 912 tech book to refresh my memory on torque sequence for the head nuts. I also read the installation procedures in the 'Orange 912 Book'. Now, in addition to the O-rings, the Orange Book specifically states to install head washers under the nuts of the external head studs, but they don't mention anything about installing washers on the internal studs.


Are there supposed to be washers under the internal head nuts? ... it's the only way the internal nuts fully seat. Is there something else I should check for?

[djdsc]

Parts book indicates 16 head bolt washers, 8 o-ring gaskets..

[ironhorse]

Thank you, Jung

Now if I could only remember where I stored the fan housing. I found the boxes with the oil filter housing, filler can, generator with the fan assembly, the carburetor and the throttle linkage, but not the fan housing

Where can something that large hide ???

[NICE 69 S]

If you leave the washers off, the head bolts inside the valve covers will crush the aluminum head all around them. Bought an engine once and found both heads had to be welded up and machined around these 8 head stud holes. Just don't understand how someone could do that and not realize there was a problem?
Bob B

[ironhorse]

Yeah, I checked the one head I had repaired ... will have to take a good look at the other side when I get it off (I noticed you already saw my other thread, Bob). I appreciate the heads up (no pun intended) ...