[Healeys] A90 Head Update

[gradea1 at charter.net]

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:  

	* 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.
 	* 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. 
 	* 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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