"Faure, Marin" <marin.faure@boeing.com> wrote:
>Assuming I'm facing the "time to change to an unleaded
>head" situation, I'm curious which would be the more efficient
>solution. Have the original head on my engine overhauled and
>refitted with hardened valve seats and the appropriate valves,
>or simply buying a ready-made, complete unleaded head from
>Rovers North, etc. I like the idea of a bolt-on solution, as
>opposed to running around hunting up a competent shop,
>collecting the necessary parts, etc.
There are only two situations where I might consider using a "pre-made"
head: the vehicle was my one and only means of transport. The other is if
the head is truly hosed with stress cracks. If the vehicle is not needed
for daily transportation, go the machine shop route.
>How common a procedure is this (the installation
>of hardened valve seats in a head with machined-in
>seats), and what sort of shops tend to do this
>kind of work?
Quite common...any decent machine shop should be able to handle it. it's
not exactly 'rocket-science'....
>It appears a complete unleaded head (stock head,
>not some sort of semi-performance head) runs
>in the neighborhood of $1,000 by the time it's all
>said and done and shipped. Is having an existing
>head overhauled and set up for unleaded fuel that
>much less by the time it's over?
I think I spent something like $250 when I had the head overhauled a year
or so ago. And that included the cost of the new valves, seats, amchine
shop work and magnafluxing.
Of course, the deciding factor is the health of the old head. Have the
shop magnaflux the head first...or, if you are really 'old school' use the
french chalk method. If there are any cracks, go for the new head, even
though the old one could be welded and repaired.
Have the shop buy the valve seats. They will have the proprietary cutters
to match whatever style of seats they buy. Even with carrying in the head
to a shop, you shouldn't be without the vehicle for more than a day, if you
make prior arrangements. I removed the head one evening, dropped it off
the following AM and picked it up on the way home that day.
Buy two 1/2 by 5" 24 bolts and cut the heads off. Machine a screwdrive
slot in each. Use these guide bolts to keep the head gasket in place on
refitting. Composite head gaskets get fitted dry. Copper-jacketed ones
get oiled. Make sure the bolt holes are clean and dry with just a schmear
of copper-anti-sieze.
Liquid in the bolt holes (glycol, WD-40, oil, etc.) will cause
'hydraulising' and possibily breaking out the bottom of the bolt hole.
Cheers
*----jeep may be famous, LAND-ROVER is legendary-----*
| |
| A. P. "Sandy" Grice |
| Rover Owners' Association of Virginia, Ltd. |
| 1633 Melrose Parkway, Norfolk, VA 23508-1730 |
| (757)423-4898 (757)622-7054 FAX (757)622-7056 |
| |
*----1972 Series III 88"----1996 Discovery SE-7(m)---*
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