GT6 cylinder heads

[WhiteV]

Hi --- Is there a straight forward way to tell the difference between a head from
a early MK 3 flat-top piston from a later recessed/dome piston head -- is there a number on the casting etc. We have

31X ?   308351   516816   from recessed/dome as we have block

X04     308351   517528    from ?  no block

with a vernier guage we measured a significant difference in chamber depth

cheers

[WhiteV]

Thank you Spitbang

We will have to recheck block number which had 516816 head on as
techical data says flat top pistons, but block contains dome pistons--
do we have a mismatch hybrid here --- sorry we have no vehicle history

could someone have put dome pistons in to compensate for what appears
to be a low CR head originally flat top?

please comfirm GT6 mk3 dome piston head number listed is 219015 because up
the page is GT6 mk2 dome piston 218255 which i didnt know existed-- thought
all GT6 mk2 were flat top?

please clarify if poss----- not going out in the rain again!

regards

[rotoflex]

WhiteV wrote:

please comfirm GT6 mk3 dome piston head number listed is 219015 because up
the page is GT6 mk2 dome piston 218255 which i didnt know existed-- thought
all GT6 mk2 were flat top?

Another report of domed pistons in the Mk2/+ engines!

Folks over the years have sometimes mentioned to me here in the US that some of the GT-6+ engines had domed pistons, & the New Zealand folks are reporting them for the Mk2 on their web page.

I asked here once about them, & folks said they'd never heard of domed pistons in any GT-6 engine except the last Mk3's.

The "Mk1" & Mk2/+ parts manuals have 2 parts numbers for pistons but no indication of the difference:
139809
149976

The Mk3 parts manual lists 2 parts numbers for pistons:
144976  (Fitted in all USA engines, but only up to engine # KE/KG 10 000 in other markets, so these are the flat pistons)
158112 (Fitted from engine # KE/KG 10 001 up in all non-USA markets, so these are the late Mk3 domed pistons)

What was 139809?  A flat-topped piston supersed by a better design flat-top piston?
Were the domed pistons competition equipment?  Don't know about the GT-6 & Mk2/+ (before my time), but factory competition parts were not listed in the parts manuals, but in separate mailings for the Mk3.