Custom bobber with a 2004 EVO 80" crate motor in it. Had a leak in both front & rear head gaskets. Replaced them both with the Cometic MLS head gaskets. Torqued head bolts down to 42 ft-lbs, put everything back together, go to start it, and I'm getting air coming out from where the new head gaskets are. I've never used these particular head gaskets before, is there anything special I should be doing when installing them.

 

First off, you need to make sure the threads are totally clean and lightly oiled, you gotta wire brush the threadsrun the nuts down them a few times and get it all squeaky clean before starting reassembly.

Check that they are going all the way down and also check the studs are not loose in the cases.

Then, any non-Harley gaskets usually come with a sheet detailing torques and tightening order, use those and only those.

 

Did you use o-rings with these gaskets? If so the your gaskets will leak. If not then check the installed height of the studs. did you LIGHTLY oil (Too much can hydraulic the nut and give you a premature torque reading) the stud/head bolt to include the flat area where the bolt and head meet? Answer these questions and then we can go from there. Hope this helps.

 

problem solved. it was the o-rings on the alignment dowels. must have missed them when i cleaned down the top of the barrels. thanks guys