Do your pistons come out of the block?(pics)

crafty

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#1
I needed to rebuild after 140,000 miles, so I put in .020 over JEG pistons. I know that the 7M is supposed to be a non-interference engine but the piston actually comes out of the block a little bit!!

There was .009 taken off the block and the head has been shaved twice .005 the first time and .006 the second. A total of .020(.5mm) I plan on using a 2mm head gasket.

Does anyone have a pic of the stock piston in the block? Does it actually crown out of the bore?

http://img.photobucket.com/albums/v335/dms03/Jeg5.jpg

I posted this on SF and got 45 views and not a single response.

Thanks, Dennis
 

siman

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#2
Well using a 2mm headgasket will take care of the clearance problem...though you might have a problem with heating on the ring lands or sides of the piston, though i am NO WHERE NEAR an expert on this, thats just something that i would think about...

weird situation you have there...maybe some more compression for your luck self will give you that extra kick :x:

good luck bro, email Dr.Jonez or Adjuster or someone of significance here...that might be better...1 on 1 convo
 

lagged

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#3
siman said:
good luck bro, email Dr.Jonez or Adjuster or someone of significance here...that might be better...1 on 1 convo
so no one else can benefit from the answer to his question?
 

Supra Blues

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#4
Yeah, lets get some input on the board on this so the rest of us know too.

But I think a 2.0mm MHG will probably take care of any clearance issues. Get one and put it on and see what it looks like.

Your compression will def be higher too.

Let us know what you find out.
 

crafty

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#5
I called the machine shop and asked them to check to see if there are limits to the amount that can be removed from the head. They said the reference manual does'nt have any max or min head thickness. It only lists' what the stock head hieght is.

I really don't want a high comp motor. I run 14 psi daily and 22 at the track (or when I'm feeling the effects of boost deprevation)

I really wish someone else could check their motor.

Isn't there someone out there doing a BHG job????

Here is another pic showing a piece of paper fitting under the file.

http://img.photobucket.com/albums/v335/dms03/Jeg6.jpg

Dennis
 
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Race Bred

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#6
i may be able to check later on today/tomorrow. I have the crank/rods/pistons ready to go in. I just need to find the time. The machine shop took .012 off my block for reference...
 

suprra_girl

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#13
well mine are .015" above the block and survived... but then again i never broke my cambelt or set my timing wrong on purpose to find out if it was now interference lol
 

crafty

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#14
Thanks TurboA and Supra girl, but after seeing Defiant's piston sticking out,(holy---) I feel pretty confident my motor will be OK.

And thanks for the picture Allan, you have put my fears to rest.

By the way, I had posted a while back about which bearings to use. I was concerned because my journals were a little under the recommended spec(.0002ish) I miked the crank and bore of the block journals and came up with my own numbers, then ordered the corresponding bearings. I put it together and according to the plastique gauge all came out within specs.(Yeah for me)

Dennis
 

DEFIANT 7M

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#15
crafty said:
By the way, I had posted a while back about which bearings to use. I was concerned because my journals were a little under the recommended spec(.0002ish) I miked the crank and bore of the block journals and came up with my own numbers, then ordered the corresponding bearings. I put it together and according to the plastique gauge all came out within specs.(Yeah for me)

Dennis
I knew you would figure it out :icon_wink
 

flubyux2

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#16
so wait, spec is like 0.010" above the deck on an unshaved motor?

cuz i have 0.017" taken off my deck. the fire rings on the stock HG really did a number on my block. its got a HKS 2.0mm on it now, and the cylinder head isa bout shaved to its service limit.

i guess i got some serious pop-up pistons !!!