[Healeys] A90 Head Update

[Bob Spidell]

Thanks for the update, Alan. Good Luck!
Bob

On 2/2/2021 6:01 PM, Alan Seigrist wrote:
> Hi Bob -
>
> This gasket was put on the car only about 5K miles ago if you can 
> believe it, but the car sat for about 10 years afterwards...  I've 
> checked both the head and deck with a rectifier (see pic), both are 
> very nicely flat and do not need to go to the machinist.  Both are 
> flat to within 1/1000 on the surface... which is less than the error 
> on the rectifier!
>
> I have the previously removed very old copper gasket which I saved and 
> it has no signs of gas leaking between cylinders compared to this 
> newer gasket that I just removed.  I discovered a few things:
>
>  1. The old gasket is made with better quality, softer copper, and is
>     thicker than the newer gasket that was put on.  The old gasket
>     that showed no problems is 1.8mm thick after being installed, the
>     new gasket that failed is 1.5mm thick after being installed.  The
>     old gasket is very nicely marked as to orientation, directions,
>     copper compression rings are thicker, etc., etc.,  Clearly the
>     older gasket was made to work in circumstances where the mating
>     surfaces weren't always perfectly flat.
>  2. I highly suspect the mechanics that installed the head last time
>     did not torque the head in the proper sequence, quite possibly
>     working from the outside in.
>  3. The head stud mount holes on the deck were raised a bit in couple
>     places and may have caused the head to deflect a little, possibly,
>     but they don't seem to have been enough to make a difference... I
>     have already filed those holes down.  Micheal Salter has told me
>     to run a countersink to debur the hole.
>
> It's a weird one, I think possibly a combination of all three issues 
> above.  Let's see how she goes after I finish the job.  Ultimately one 
> thing I learned is I cannot anymore rely on mechanics that I do not 
> know well to do work on my car... I end up having to redo everything.
>
> Best,
>
> Alan
>
>     On 2/1/2021 11:23 PM, Alan Seigrist wrote:
>     > All -
>     >
>     > Got the head off.  Sure enough the gasket blew between 3&4 .  some
>     > evidence of gas flow between 1&2 as well. Last pic is of me
>     standing
>     > in the engine compartment lifting the head off, just to make all of
>     > you jealous ... :D
>     >
>     > Cheers,
>     >
>     > Alan
>     >
>
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