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vch headgasket

Posted: Thu Jul 04, 2019 5:01 pm
by charvey
1952 VCH alloy Head, 5 bolt is the head gasket a thin copper type or a composit type and where can I get one from Thanks Clive

Re: vch headgasket

Posted: Fri Jul 05, 2019 8:16 am
by charvey
Hi All,
After going through old forum messages and a couple of other sources I found there is no headgasket on 5 stud alloy heads, but I found out the top hat nuts homemade needed more thread in a couple of them and shortening so as not to bottom out so I was slightly tightening on to the thread not the head any way can finish off rebuild but I cannot get my head round no headgasket just very clean metal to metal torqued to 28Lbs also smaller o rings than I fitted first time to the push rod tunnels but it works hopefully.Clive.

Re: vch headgasket

Posted: Fri Jul 05, 2019 9:44 am
by Bob.Murphy
The head and liner have to be 'lapped' together with fine grinding paste.

I had to machine-away some alloy from the top of the barrel to get the head and liner to make contact and it all works OK now.

I wasn't sure how much clearance to leave around the liner, as the head has to be pulled down to keep the joint tight but I didn't want it bowing over the liner. I opted for about 0.010" (I could just glimpse daylight between the head and barrel before tightening).

I would be interested to hear what others think.

Hopefully you have got this all sorted now.

Bob.

Re: vch headgasket

Posted: Fri Jul 05, 2019 11:12 am
by pete.collings
I had a problem in the past with blowing from the head/barrel joint when mating a VHA head with a new make alloy barrel. I think the head had been lapped in too many times, as there was alloy to alloy contact between the head and barrel, rather than liner spigot to head contact.
I cured this by delaminating a composite copper head gasket used with Velocette singles, a piece of which neatly sat on top of the liner spigot.
Like Bob, I made sure there was a small gap between the alloy faces, although I cannot remember exactly what the gap was.