Head Bolt Torque Pattern

[ButchPetty]

I just stumbled across this: http://www.westerbeke.com/ServiceBulletins/sb_223.pdf

I noticed a big difference in the tightening pattern than the one in my Moyer Marine Bible. Is there a reason for this difference that anyone could explain? Is it just the years of knowledge that "Don" has acquired?
Just wondering.

[Dave Neptune]

Patterns

Butch, I'll chime in here. I have not seen the MMI manual and if it is a bit different no biggie. I have done 100's of head replacements and don't even look for anything but the final torque value. When tightening any flat surfaces together you always work from the "center out" in a concentric pattern. I have seen many differant patterns on the same head and it is just their instructions. Most important especially on the A-4 as it is a "thin" head is ti get the head set with a low torque setting and go over it a few times steadily increasing the torque a bit at a time. When the head settles in and the amount of rotation to achieve the torque value is consistant with the value you are working with then you can begin to increase the torque a bit more until the final torque setting is achieved. Retorque after it has set for a while and especially after the first time it is fired up and warmed. It is also a good idea to retorque after a couple hours of operation. Some gaskets such as the 2 required in the A-4 compress quite a bit requiring resetting after the first couple of runs. I built some modified Rotaries and the torquing sequence on the housings takes forever and you are only going to 17 ft lbs of torque.

Following the above procedure I have never had a gasket failure under "normal" operating conditions.
Note if you use a bit of Av grade (my personal recomendation) around the edges of the studs and cylinders torquing will take a bit longer and more finess. This is because a bit more squeezing to compress the sealent is necessary. I replaced my head 27 years ago in this fashion and it still is in great shape, no signs of water anywhere around the studs or head.

Dave Neptune

[hanleyclifford]

Butch - I don't like that pattern Westerbeke recommends - suggest following Don Moyer's advice.

[ButchPetty]

Ok. I didn't assume it to be a biggie either. I was thinking maybe Don knew something the folks a Westerbeke didn't.
And yes, I'll stick with the MM manual also.