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View Full Version : Do your pistons come out of the block?(pics)



crafty
April 16th, 2005, 05:21 AM
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
April 16th, 2005, 05:43 AM
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
April 16th, 2005, 08:20 AM
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
April 16th, 2005, 08:28 AM
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
April 16th, 2005, 09:06 AM
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

Race Bred
April 16th, 2005, 10:52 AM
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...

crafty
April 16th, 2005, 11:25 AM
Race Bred: That would be great!! Do you have stock pistons or aftermarket?

Dennis

DEFIANT 7M
April 16th, 2005, 11:43 AM
Yes the stock piston does come out of the deck .012-.020.

DEFIANT 7M
April 16th, 2005, 11:58 AM
Someone asked about deck height last week or so. I verified my reply and it's correct.
http://www.supramania.com/forums/showthread.php?t=212&highlight=deck+height

Hope this helps...Just for :crazy1: here is a pic of the stock piston on a my stroke @ TDC
http://www.villagephotos.com/viewpubimage.asp?id_=10237863

crafty
April 16th, 2005, 12:08 PM
Thanks Defiant, I measured, my piston comes .010" above the deck. So I should have enough clearance.

Dennis

DEFIANT 7M
April 16th, 2005, 12:29 PM
:bigthumb: No problem...

turboa7mgte
April 16th, 2005, 02:58 PM
I just got my 2mm HG and have my motor With JE's still sitting on the stand if you need Pics.

suprra_girl
April 16th, 2005, 04:22 PM
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
April 16th, 2005, 04:27 PM
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
April 17th, 2005, 10:11 AM
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
April 17th, 2005, 11:56 PM
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 !!!