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1954 dommi head gasket

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1954 dommi head gasket

Posted by lee_rice at August 19. 2017

Afternoon,

 

HELP PLEASE.

 

just fitted andover head gasket to all iron, spigot barrel 500cc. still 'blowing' from head gasket. not sure if crank case pressure up pushrod tube?? of out of cylinder?(100psi per side).

 

how thick should gasket be? gasket at all?(when head sat on gap is about the same as current gasket... should I put 2 gaskets on??

 

thanks

 

lee

Re: 1954 dommi head gasket

Posted by John Shorter at August 19. 2017

Previously lee_rice wrote:

Afternoon,

 

HELP PLEASE.

 

just fitted andover head gasket to all iron, spigot barrel 500cc. still 'blowing' from head gasket. not sure if crank case pressure up pushrod tube?? of out of cylinder?(100psi per side).

 

how thick should gasket be? gasket at all?(when head sat on gap is about the same as current gasket... should I put 2 gaskets on??

 

thanks

 

lee

 

Re: 1954 dommi head gasket

Posted by John Shorter at August 19. 2017

Hi Lee,   I had exactly the same problem, after fitting new valve guides, a few months ago.  You must appreciate, the head is now over 63 years old, and may have been skimmed, in the past.  I took my barrels, and head to a machine shop. The head showed signs of previous skimming, and required a further 2 thou removing, to make it perfectly flat.   The machinist lightly cleaned the grooves (that go over the spigots) but, you can´t remove much metal, or the pistons might touch the valves.  I don´t remember how thick the, copper, gasket was, but, not thick enough!  The head sat on the spigots, before it made contact with the gasket.   Fortunately, I found a local firm who could make a thicker gasket (no help to you, I now live in Valencia, Spain!).

You should not have the bother of removing the barrels.  Place the head in position (without gasket), and check what gap, if any, there is between head and barrel.   If a thicker gasket is needed, I understand Andover will make one to order.   

p.s. I initially tried two gaskets, didn´t work! ( possibly because the head needed a further light skim).

You may get further posts rubbishing this reply, from "Experts", who were not even born when your bike was built, I was, and was riding one.  The above worked for me.  

 

 

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