Al Gietzen wrote:

On the sparkplug side; front side housing.  There is a hex head plug
at the top - about 125mm thread; and a ~150mm allen head head plug
about 6-7" down the side (just above where it flares out at the
bottom).  What are they?

I'm guessing allen is water jacket and hex head is oil?  What
are/were they used for?

Thanks,
Al

You mean 12.5 mm. That sounds like somebody added that. That is
in the region of the main oil gallery.

The lower one communicates with the water jacket.

Paul Lamar

Hi Al,

Correct.  The hole/plug to which you refer above with the hex
headed plug is used for the oil gallery for the turbo bearing supply.

Normally, this hole is blocked off with a brass plug (just like all the
other holes needed for drilling the oil galleries),  but on turbo
engines,  it is "spot faced" and threaded to take a banjo fitting &
hollow bolt to supply oil to the turbo.  Depends on the year and the
model.

Sometimes,  if a set of turbo end housings are used on an NA
engine,  it is blocked ff by the builder.  (See,  turbo housing ports
are somewhat bigger than the 6 port housings, (unless you go mad
with a porting tool),  and most especially the REW '93 -on engines.
 They are huge!!  But I digress.

The Allen headed plug leads into the water gallery.  Very ahndy to
get differential temps frront & rear.  On some of the earlier front
housings,  there plugs have/had a raised square head like a normal
BSP/GAS plug).  On certain models,  there is a switch/sensor.
Not on all models - again,  it depends on the year and the actual
chassis model to which the engine was originally fitted.

Cheers,

Leon Promet
Best Wishes & Kindest Regards,

Leon Promet
Aerota.com
leon@aerota.com
0408 223 675

 
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