[Healeys] A90 Head Update

[Alan Seigrist]

Hank -

Is the spray on sealant silicone, or is it a non hardening kind like
hylomar?  I'm a little concerned to use this as it may make disassembly
difficult later if I have to strip the engine down again.  What is your
experience?

Thanks,

Alan

On Wed, Feb 3, 2021 at 10:46 AM <gradea1 at charter.net> wrote:

> Alan-two questions: do you know if the car overheated at any time after
> the replacement of the head?
>
> Secondly, do you have any idea what torque they used to tighten the head,
> even if they did not go in order?
>
> A couple of us, who have been doing this for awhile, decided on about 80
> FT LBS. as max torque. There is no book spec. That is a spec for that size
> stud and nut. The tightening order in the workshop manual is strictly
> adhered to, and the torque is brought up in 1/3 increments.
>
> Again, I sprayed  both sides of my copper gasket with a light coating of
> Permatex copper seal.
> I used a Payen gasket which was marked top/front. Yea, the good old
> days...Hank
>
> -----------------------------------------
> From: "Alan Seigrist"
> To: "Bob Spidell"
> Cc: "Healey list"
> Sent: Tuesday February 2 2021 6:07:37PM
> Subject: Re: [Healeys] A90 Head Update
>
> 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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