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1986 Holden Piazza Head Gasket - Wanted To Buy.

Posted: Sat Dec 04, 2010 5:43 pm
by sbs
Hi there Folks,
I am in need of a head gasket for my Holden Piazza and I wonder if anyone can help me please? Even if it is to direct me to a supplier it would be much appreciated. I am in Western Australia.
Thanks and I look forward to any help. Best wishes, sbs.

Posted: Tue Dec 07, 2010 4:34 pm
by wedgenut
I have some here but they are easy enough to get from almost any parts place. Don't ask the 10 year old behind the counter for a Piazza head gasket. he will just pick his puss filled nose and start crying. Ask for it as Holden or Isuzu 4zc1 engine head gasket

Posted: Tue Dec 07, 2010 10:13 pm
by sbs
Hi Wedgie,
Thanks for letting me know you have head gaskets, if I have any problems getting one I'll get in touch. Cheers, sbs.

Posted: Mon Dec 20, 2010 6:22 pm
by IZU069
Damn - it's for a G200Z...
It's listing said Piazza 1/1990-12/1993, but on checking, the 4ZC ACL headgasket is a BP980 (not BM490).


But since I went to the trouble....
eBay - ACL montorque BM490MT isuzu jackaroo holden rodeo etc - AUD$50.00 Buy It Now; free postage.

Posted: Tue Dec 21, 2010 9:42 am
by Piazza_man
I have a solid custom brass (i think it's brass) gasket if anyone wants one. It was made to de-compress the motor for higher boost applications. Also handy if the block and head have been machined and you want to bring back the compression ratio to factory specs. It was one of the last things I bought before deciding to sell the car. In other words never used. Not sure of the thickness but I can find out if asked.

Should I post this in a new thread? Don't know.

Posted: Tue Dec 21, 2010 10:02 am
by IZU069
What - not copper? You have to have copper for performance engines!
Or if you like pulling the head off often and don't mind lots more corrosion! Ah - there are so many street racers these days - they used to be confined to the track.


But a decomp plate is different. (As usual, I was having a go above. A recent discussion with someone about all the high performance Isuzus (Read: Geminis) with ACL pistons... ie, turbos etc. More money than sense.)


See how the response go here (to your plate, not my sarcasm).
But later you should advertise in the FS section.


Of course, maybe the Gemini sites are better - they can require silly things for their hot engines. A lot of the are deck-heads. (Did my Kiwi accent come across eh?)

Posted: Tue Dec 21, 2010 11:55 am
by Piazza_man
You could be right buddy re copper. I thought of copper before posting, but wasn't sure. It's about 3mm thick. Isn't copper expensive these days? I actually had it made for specifically increasing boost, didn't know about special de-compression plates. There you go. I've been out of the game for so long that it proves I have no freakin' idea. I did warn ya buddy. Feel free to correct me at any stage. I'm never too proud to acknowldge genious. BTW is there a quick way to verify that it is copper? But I'm sure it's copper now.

Your last comments remind me of a line in a commercial currently running in Oz re. Timber deck oil. The wife walks past the husband and says "Ah, boys and their decks". Bloody funny commercial.

Posted: Tue Dec 21, 2010 12:43 pm
by IZU069
Ah - I love getting the good oil!
(Especially if she rubs it in. Alas I get more rubbing in from these forums!)


When it comes to copper gaskets, I'm "not in the know" either - except that they were used by racers for various reasons including that the engines were pulled down every few races.
Aluminium and iron are bad enough, but with copper in between...!!! IE - block and heads.
Copper gaskets were more common back in iron head days (before they went to wood... wood; head... my bad!)
But many use them because they reckon they need them to handle high boost & compression. And for that they need rubber-ringing. And on it goes....
The rest of us blow away their hot copper gasketed cars with simple exhaust mods on standard engines - but never let me tell you how to do that! :yawinkle:
And yes - I loved the Cu gaskets in my old motorbike because you just annealed and reduced them. But that was not liquid cooled!


But there are also de-compression plates. Originally used because people used to deck (shave) their heads for compression (rather than a one-off block decking). And since over time heads get shaved anyhow, there becomes a shortage of shavable heads. (ie - Most learn to deck blocks instead...)
De-comp "gaskets" or spacers are used where shaved heads are still usable but are too high in compression.
But the latter has also become popular with the move away from base compression to turbocharging - ie, a 40% power increase under boost without the need for leaded or "anti-knock" petrol etc.


Other than brass visually being less copper colored (d'oh!), I'm not sure how to pick the difference. Conductivity is another method (brass conduction is much less than copper).

Maybe some local engine guru could see?
Or a more knowledgeable reader might chime in...
Or advertise in here and see if someone knows....

Posted: Tue Dec 21, 2010 4:01 pm
by Piazza_man
Thank m8. It sounds like we've also hijacked sbs's post too.

Posted: Tue Dec 21, 2010 5:14 pm
by wedgenut
The "gasket" you have is not a gasket, it is a shim for use when the head or block has gone past mimimum or if you want to reduce compression. It should be annealed before use to soften it (it will be copper by the way..or should be) The act of annealing will confirm it. In its non annealed state it will be quite rigid, heat it with a gentle blowlamp flame evenly and watch all the pretty colours, this will not only confirm that it IS copper it will also anneal it and if you lift it from one end afterwards you will see it wants to droop and is no longer as rigid. In other words it is now annealed and soft enough for use. To use it you need to go to an engine reconditoners who will sell you some proper adhesive/sealant to apply to the block surface and the block side of the shim ( they must always go between the block and the head gasket as you don't want copper in contact with alloy heads) I'm not going to wither on about the galvanic scale etc, just believe me. You will also need a new head gasket because you can't seal the head with a shim only. Follow the instructions and it willl go well. If you short cut the annealing and sealing steps it will fail. Trust me on that.

Posted: Tue Dec 21, 2010 5:37 pm
by Piazza_man
Handy info there guru wedgenut. Should I bother with putting the shim (& the adhesive/sealant that came with it) up FS? I mean we are talking about a specialized part now, not OEM. Doesn't even worry me if I don't. I don't even know what they're worth these days.

Sorry sbs. We've really gone off topic now.

Posted: Tue Dec 21, 2010 7:42 pm
by wedgenut
Copper head shims usually cost between $35 and $50 and the adhesive is around $25 for a small tin which is useful for other sealing purposes as well.
Is it a G200z or 4zc1 version? You could always ring up your local ACL agent which is probably Repco or similar and ask them for a cost

Posted: Tue Dec 21, 2010 9:11 pm
by Piazza_man
Thanks for that. I'll look into it.

Posted: Wed Dec 22, 2010 8:42 pm
by IZU069
ACL agent - what's that?


I found out my "cheap but excellent" Wasp pistons were ACL (namely RePower 4RP6586-1.00 & Ringset PS1465-1.00 for G161).

I figured I'd sacrifice a head gasket and re-ring her whilst I had her out for her main seal replacement (she's only done 170,00km since her 2000 rebuild).
The ACL office wasn't answering....
They went into receivership in 2009.

Bluddy r'soles - couldn't they have waited just another year?

Now I will have to use the G200W.
Eventually.

Posted: Wed Dec 22, 2010 9:40 pm
by wedgenut
They went into receivership in 2009.

Bluddy r'soles - couldn't they have waited just another year?
WHAT???? Check again, I just ordered some thrust from ACL NZ (through APPCO which is owned by Repco as they wouldn't sell direct to me) and they had to get it over from ozzie head office. that was less than two weeks ago