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Piston to head clearence
Just can't stay away
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2015/3/22 7:42
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Just wondering what the smallest clearence people have run between the head and piston.

Im trying to get the quench as tight as i can engine will rev to 7500-8000rpm. I have not checked how much the piston rocks yet but will get to that.

Any idea how much a rod will stretch at those rpms?

Posted on: 5/2 13:24
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Re: Piston to head clearence
No life (a.k.a. DattoMaster)
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I'm going to guess the minimum is .6mm as the competition head gasket is .6mm, I've always found Nissan Comp/Nismo's specs to be pretty spot on.

As for the rods I've used the standard rods for the last 30 years, in conjunction with .8mm & 1mm crush gaskets and rev the motor as high as 8600 RPMs without issue. Note I'm even using the standard rod bolts.

If you can find a copy of the Datsun N10 competition tune-up manual that offers lots of good information; I've got a PDF copy buried somewhere I could likely dig out.

Posted on: 5/2 21:03
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Re: Piston to head clearence
Just can't stay away
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Il definitely try find this tune up manual.

I did measure the piston height in relation to the deck and it sits about 0.24mm below the deck (maybe it was 0.34mm)

Which means even with a 0.6mm gasket we get 0.94mm of clerence which is why am getting the block decked.

But i will obviously have to remeasure with the new flat top pistons.

Posted on: 5/2 22:15
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Re: Piston to head clearence
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0.75 to 0.50 mm

which generates good quench for power and allows for rod stretch. stock rods & rod bolts are fine

Posted on: 5/3 21:52
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Re: Piston to head clearence
Just can't stay away
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I did come across those figures in the tech section.

From my research alot of the v8 guys run much more then 0.5mm closer to 0.85mm.

Has anyone successfully run 0.5mm in a small bore engine like ours?

Posted on: 5/4 0:23
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Re: Piston to head clearence
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Yes, and some V8 guys build their engines with 0.75 mmm (0.30 inch) piston-to-head clearance. Isn't that due to rod stretch more than bore size? The larger bores can have more piston rock so bore size does come into play, but apparently rod stretch is the biggest factor

* NISSAN COMPETITION HEAD GASKET has an uncrushed thickness of 0.8mm/0.032
* MLS head gasket that I ran was (crushed thickness) 0.50 mm (0.020 inch) which was in my 1522cc A14, I ran it up to 6500 RPM fairly often. Pistons were even with the deck

0.75 mm is a conservative choice for the A-series in my opinion

Posted on: 5/7 10:56
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