The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: Peter Gee on 11.07. 2019 13:53

Title: Head Gasket: Sandwich or Solid type?
Post by: Peter Gee on 11.07. 2019 13:53

I have a modern solid copper gasket but also a supply of 60 yr old Payen types that feature an asbestos /mix core sandwiched between two thin copper sheets...the bores opening are also gusseted for strength. Which should I use, and will it matter if I use an A10 gasket for an A7SS?

Title: Re: Head Gasket: Sandwich or Solid type?
Post by: Black Sheep on 11.07. 2019 14:42

I find solid copper gaskets are prone to oil seepage despite my best efforts of annealing etc so I stick with copper/asbestos ones which are fine.
Ideally, you should use A7 gaskets for an A7 but A10 ones do work perfectly well. My A7 Star Twin is running with an A10 gasket because I have had difficulty sourcing A7 head gaskets.

Title: Re: Head Gasket: Sandwich or Solid type?
Post by: Peter Gee on 11.07. 2019 17:05

Thanks sheep, indeed I had the same problem trying to source A7 gaskets. These Payen are from 1950's de-coke sets and in perfect condition.

Title: Re: Head Gasket: Sandwich or Solid type?
Post by: RDfella on 11.07. 2019 20:36

Concur with BlackSheep - IMO solid gaskets lack the flexibility to adjust for movement when things get hot and slight movement (gaps) occur betweeen head and barrel.

Title: Re: Head Gasket: Sandwich or Solid type?
Post by: ironhead on 11.07. 2019 23:17

I always use solid copper gaskets but a trick I learnt many years ago is after annealing, and cleaning any oxide off I lightly paint them with aluminium silver frost paint ( just like the japanese do on there tin gaskets) never had a problem whether cast iron or alloy heads.

Title: Re: Head Gasket: Sandwich or Solid type?
Post by: Peter in Aus on 12.07. 2019 00:33

I use solid carbon fiber head gaskets supply by Draganfly. see my post  https://www.a7a10.net/forum/index.php?topic=10058.msg86623#msg86623  (I don't think that is quite the right way to get to that topic? some one might put me right there) The bit I like you don't have to re-tighten the head, and so far no oil leaks. 11000 miles and 3 years later still all good. *smiley4*

Title: Re: Head Gasket: Sandwich or Solid type?
Post by: Peter Gee on 12.07. 2019 08:55

Thanks all...yes retorquing could be a right pain, given the bolt locations on an A10...however I tend to build engines slowly, leaving the gasket for a  days then adding another lb or torque..for a week .. so I rarely have to re-tighten....I certainly would not have to take the head off again to fit the pushroad comb!

Title: Re: Head Gasket: Sandwich or Solid type?
Post by: TT John on 16.07. 2019 15:26

I think solid copper gaskets are the better of the two, I don't think I am bias because I sell them,(not for A10s though), if fitted correctly there should be no need to replace, the sandwich ones were okay in there day but now with modern soft copper, which is now readily available lazer cut you cannot go wrong, in answer to whether the same gasket will work on an A7ss, yes is the answer but you may drop a slight bit on compression but nothing really noticeable. HTH

Regards TTJohn

Title: Re: Head Gasket: Sandwich or Solid type?
Post by: Klaus on 16.07. 2019 16:49

I use solid copper plats to cut my gaskets for every barrel special. I have around 10 gaskets and on one fits realy good, so I descide to go this way, with a little increase the compression, by using 0.7mm plates. They are better to handle.
As I know for the A7 are no solid gaskets available.
Fitting this gaskets with a light smear of HTsilicone I never had retorque the headbolds, with no problems.

cheers Klaus