7mge compression test

IJ.

Grumpy Old Man
Mar 30, 2005
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IJ.;1321125 said:
If you get a chance measure the Deck to Valve cover seal surface

HG

and the block from the Main bearing saddle to the Deck surface, as I said I wasn't aware of different pistons in the Japanese/USDM engines as we got the Jap spec engines here.

But having said that the change in dish volume still wouldn't account for your 230+psi readings.

in case you missed it...
 

dopeassjackson

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Mar 13, 2009
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IJ.;1321133 said:
in case you missed it...
4.570 on the head and i dont have the crank out on the JDM engine but the US main to deck is 8.712. both oil pan surfaces to deck where about the same.
 

dopeassjackson

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IJ.;1321133 said:
in case you missed it...

IJ.;1321136 said:
Just checked with a bud here 9.8:1 V's 9.2:1.
(learn something new every day)
so there are different compression numbers. thats odd that the factory manual dosnt say that. any more power out of this?
 

dopeassjackson

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IJ.;1321144 said:
Virgin head then so that rules that out as being a factor.

What HG was in it?
couldnt find a make on it and i looked hard. it was graphite paper gasket though. some of the coolant copper rings looked a little warped but not blown yet.
 

dopeassjackson

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IJ.;1321152 said:
If you have enough octane to keep it out of detonation yes there would be some more power there.
Measure the HG at the CC ring?
i can get 93 octane every around here.
3.220
 

IJ.

Grumpy Old Man
Mar 30, 2005
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Normal HG is 1.37mm compressed yours was 1.27mm so being that tight would explain the extra crush.

I'd be checking that the head is still straight after checking it for hardness.
 

dopeassjackson

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checked it alreaty and i cant fit a .003 feeler guage under it anywhere. i took a machinist oil stone to the block and head, they cleaned up good. i actualy did a half ass re-deck on my 4runners engine while it was in the truck.

thank you for the help sir. :)
 

IJ.

Grumpy Old Man
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I'd check the cam tunnels to make 100% sure it's straight, measured a bud's 7M with the IR gun yesterday and there's a HUGE variation Front to Rear on these heads temp wise :(

Also check the Exhaust side for hardness.
 

IJ.

Grumpy Old Man
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Depends on how anal you want to get.

It "should" be straight in both checks, a quick dirty check is to strip the head torque the cams back down with no valves/springs and make sure they turn easily.