[TR] TR3A Head gasket Update #2

[Alex]

Hi Michael,

> Two observations:  first, the amount the cylinders are standing proud of
> the block deck is too much.  IIRC, 0.002-0.003" is probably the
> optimum.  You also need to check the distance at more than one
> location--at least, both left and right sides of the block, since there
> were at minimum a few blocks that were not milled parallel to the
> cylinder seating lands.

There was only one cylinder that was .006", the others were in the .005 range
with two at .000". I believe the manual called for .0055 max. The cylinders
were checked at every 90 degrees to the block, effectively providing 4
location check points. A straight edge was used to check both rock and to
measure cylinder clearance from the block deck.

You might also want to put a straightedge along
> the block at various places to see if there's any warpage (same thing
> with the head).

See #1 above. This was accomplished actually with two machinist straight
edges. One 6" and one 12" straight edge.

Second, if you're certain that the head nuts were
> torqued as you described, it's possible that the studs are stretching.
> If the nuts have been over-torqued in the past (say, if someone oiled
> the threads when the spec requires dry threads), it's possible the studs
> have yielded, which means that they will continue stretching under load,
> effectively reducing the clamping force on the head.  It would be wise
> to measure the studs against a known good stud. A stud noticeably longer
> than the good one (more than, say, 0.010-0.015") has probably failed.
>
In the 80's the engine was rebuilt and placed back in the car with minimal
drive time. I believe now that the head was never re-torqued. The torque
procedure is a standard procedure and the sequencing was checked against the
manual. After removing the studs they were dried and reinstalled dry. I know
you were referring to the initial installation, but we also followed this
procedure now. And in all honesty we talked about oiling them, but forgot to.
So they went back in dry.

Last, when using fiber/composite gaskets, don't blow through the head
> torquing one cycle after the other--take a few minutes off between each
> round to give the gasket a chance to compress fully and settle in.  On
> the last pass, wait a few minutes and then check them again.  Any nut
> that requires additional torquing after the third and last (105 lb-ft)
> round of torquing may indicate a yielded stud.

The head gasket is a copper one from a Curty-JMF head kit supplied by Triumph
dealers during the 70's-80's. I have three head set kits that I received with
the car. (another story)
There was a delay between sequences...and this was more dumb luck as opposed
to tactical planning, as both of us switched to take a break. It was amazing
the effort required to torque all head bolts to spec.

Our plans after checking compression is to run the car to temperature and then
re-torque or at least check it again along with doing a proper check on all
valves, etc.

Everything was completed prior to receiving this email, so time will tell if
we got it right.

Thanks for the excellent feedback.

Alex
>
> Cheers.

> Michael Porter
> Roswell, NM