Head gasket wont fit overbored 4G52

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Head gasket wont fit overbored 4G52

Postby Rally_2.6LC » Tue Oct 24, 2017 8:08 pm

Hey guys,

I've got a 4G52 which has been bored out to 90mm and the pistons sit 0.4mm proud of the block, built by previous owner and can't get in contact with them.
I cant use a standard head gasket and the 4G54 one is obviously too big in the piston bore at 92mm to use.
Has anyone bored an engine out this far or had custom head gaskets made?
Spoken to some people who say use a thin custom made copper head gasket.
I am wondering if anyone has used someone in Sydney and what the prices of copper gaskets was or know somewhere to get custom normal gaskets made.


Thanks
Matt
'75 GC daily (slowly dying)
'80 LC 2.6L rally car (generally something broken until 2 weeks before an event)
'71 GA 2.6 Turbo project (i only wanted the diff and got another project)
^This side up^


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Re: Head gasket wont fit overbored 4G52

Postby C_Fernance » Wed Oct 25, 2017 4:19 pm

Precision International sell head spacer shims in 0.8mm and 1.5mm for under $50. Not really a gasket but it might help with raising the deck height to clear the pistons.
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Re: Head gasket wont fit overbored 4G52

Postby cheaterparts » Thu Jan 04, 2018 7:20 pm

if it's any help I used a ridgecrest copper gasket on my astron build a 4G52 - from memory a 0.020 " thick gasket it worked quite well with just a spay of copper coat and some sealer around the oil return



http://www.ridgecrest.com.au
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Re: Head gasket wont fit overbored 4G52

Postby cheaterparts » Thu Jan 04, 2018 7:28 pm

just thinking back I also had the pistons quite proud of the deck at least 1 mm and possibly 1.5 mm but the pistons where machined with an angle around the outer edge and the head was set up with the same angle cut where the pistons became close - with the 0.020 copper gasket there was about 0.5 mm clearance around this squish band
again from memory there was a little bit of valve re-leaf also cut on the inlet side

this was back in 1999/2000 so some of the spec is from memory and a lot of engines were built after that
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Re: Head gasket wont fit overbored 4G52

Postby Rally_2.6LC » Wed Jan 10, 2018 11:18 pm

Thanks for the help guys.
Cheater this engine also has pistons with an angle around the edge. They sit approx 0.4mm above the deck.
From looking at the block I don't believe it has been o-ringed or sleeved.
It was build in the early/mid 90's and was in a GB rally car to start then a GE sigma rally car.
It is apparently a very strong motor and will sit at 7500rpm all day if needed.
I'll look into the copper head gaskets from ridgecrest.


Thanks
Matt
'75 GC daily (slowly dying)
'80 LC 2.6L rally car (generally something broken until 2 weeks before an event)
'71 GA 2.6 Turbo project (i only wanted the diff and got another project)
^This side up^


Formely "Matt"
User avatar
Rally_2.6LC
 
Posts: 943
Joined: Sun Mar 22, 2009 10:59 am
Location: Either under a car, on the computer or in bed...around Ryde
Country: Australia (au)


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