Supposedly stroked 3.8 liter?

greeneyegi

Well-Known Member
Joined
Feb 21, 2010
Got another tune up 1987 gn, turns into blown head gasket!
Somebody gave bad advice to this guy.
Supposedly the motor was stroked.
Stock 8445 refreshed heads.
4" downpipe
72mm turbo
stock size roller cam,lifters,ta roller rockers.
stock converter
The car wouldnt build boost.
The tps was way off and iac off also.
I told him i would fix that and go from there.
By the time the car came back I did a quick compression check and cyl 3,5 were gone.30 psi
All the other cyl were 180 psi.
After pulling the head to replace gasket,turns out, its got wrong ones installed.The builder used NA head gaskets.
The pistons arent stock.They also dont have any numbers stamped on them? My experience always showed what size the slugs were oversized. Am i correct?Maybe just stock bore?
there is good crosshatch but some real good scratches in cylinders.
Are their oversized, that arent marked on top?
And can i measure the length of cylinder while all the way down to see if it is stock stroke?
I will have alot of questions here,but first is, pistons and if the motor was bored/stroked.
I attached pics of cylinder scratches
and the pistons say "right side" and arrow on them.
Any ideas on pistons?
Going to install a 58mm turbo and put back together and fix all the rigged stuff and bring this beauty back to life.
 

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Take a cliper to the bore and measure it. They look forged but is there a ridge wider than the crown?? What is that?
 
3.82 is what i measured.
He ordered JE stroker .020 over.
Also the driver bank all say front right with an arrow
the passenger side has 2 front left and a front right on them
here is a better pic after cleaned.
Do the je pistons have a oversize stamped on them?
These just have the direction on them.
So bore size seems ok,now question is will the piston saying right bank in left be ok?
 

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I have JE's and they do not say .030 on them and mine are .030. I inherted the motor messed up and the left side pistons where on the right side and vise vera. That's ok it won't hurt anything. The scratches on the cyl walls....as long as your finger nail won't catch I 'd run it. And the pic with red circle looks like the top compression ring with ring gap showing.

I don't know of a way to measure the stroke in block, we had to remove the crank and check mine. And mine was supposed to be a stroker (I have the receipt from PO) but it was a stock stroke.

I feel your pain. No doubt you'll fix it up in no time.
 
I have JE's and they do not say .030 on them and mine are .030. I inherted the motor messed up and the left side pistons where on the right side and vise vera. That's ok it won't hurt anything. The scratches on the cyl walls....as long as your finger nail won't catch I 'd run it. And the pic with red circle looks like the top compression ring with ring gap showing.

I don't know of a way to measure the stroke in block, we had to remove the crank and check mine. And mine was supposed to be a stroker (I have the receipt from PO) but it was a stock stroke.

I feel your pain. No doubt you'll fix it up in no time.
as long as they dont come marked then i believe its the kit he ordered.
I can feel a couple of the big scratches on the cylinders, he only has 33 miles tops on this thing.I dont know what to think right now.
 
image.jpeg
Idk. Something looks wrong in these pics I'm circling or is it an optical illusion??

I could be wrong, but I've personally never seen the gap in a ring with Pistons installed In reference to my first post
 
33 miles ouch, I'd take it all back apart that sucks. They used the wrong headgaskets , probably not their only mistake.
 
Yeah even 3000 miles shouldn't have a damaged bore like that. Looks like a bad hone job without a torque plate. Or the piston is rocking in the hole. I agree with Steve. Help the guy salvage what he has invested, who built that, Pep Boys?
 
View attachment 276728 Idk. Something looks wrong in these pics I'm circling or is it an optical illusion??

I could be wrong, but I've personally never seen the gap in a ring with Pistons installed In reference to my first post
Looks to me like an oil ring retainer got folded over on piston install and never got noticed.
 
Yeah even 3000 miles shouldn't have a damaged bore like that. Looks like a bad hone job without a torque plate on an oblong cylinder. Or the piston is rocking in the hole. I agree with Steve. Help the guy salvage what he has invested, who built that, Pep Boys?
So i just went out and turned it over and took some real good pics.It seems to me the one with the bad scratches is one that the gasket came apert on.What do you think?
You can see where the burn is at the top of the sleeve where the gasket gave way.
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gasket and head that caused this?
 

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If it has head gasket damage in 300 miles it doesn't matter what gaskets were used. It saw detonation.


Sent from my iPhone using Tapatalk
 
If it has head gasket damage in 300 miles it doesn't matter what gaskets were used. It saw detonation.


Sent from my iPhone using Tapatalk
It wasnt ready to be beat on when it left the shop.Tps was @.26 and WOT was 3.7.
The wastegate rod was extended and whole thing was asking to be broke
Unbelievable what some people will do .
 
It wasnt ready to be beat on when it left the shop.Tps was @.26 and WOT was 3.7.
The wastegate rod was extended and whole thing was asking to be broke
Unbelievable what some people will do .

ESPECIALLY if they just put headgaskets on that and SHIP IT ... you got a whole lot going on there ... the bore looks like DOOKEY !
 
Looks to me like an oil ring retainer got folded over on piston install and never got noticed.
I thought the same but it would almost be impossible, you would have to hammer the shit out of it to get it in the hole. :eek:

I can hear my machinist/mentor if I brought that in.. "Well, you better do it right this time"...:confused:

And you are right, that is an $11 dollar NA head gasket. I use that gasket under my torque plate lol. But like Bison said, doesn't matter what head gasket, something made it blow.
 
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Those cylinders were detonated like Bison said.
The ring gap may have been too small and the pressure/heat from detonation butted the rings and scratched the walls.
At this time . . . It's time to question/measure everything and start over.
 
Those are some interesting looking scratches on the walls. I'm more worried about feel than looks though. Since my engines last more than 300 miles I have no real world experience diagnosing them with pics on my laptop.... How do they feel on your fingernail? What does the bore gauge show?...


Also if it says 'right bank' and 'left bank', that does matter. When there's a right and left that usually means there's a thrust offset on the pin bore. Now what's odd is that those pistons have no valve reliefs. So a 'right' piston could be installed 'upside down' on the other side and it would be the same thing.
 
Those are some interesting looking scratches on the walls. I'm more worried about feel than looks though. Since my engines last more than 300 miles I have no real world experience diagnosing them with pics on my laptop.... How do they feel on your fingernail? What does the bore gauge show?...


Also if it says 'right bank' and 'left bank', that does matter. When there's a right and left that usually means there's a thrust offset on the pin bore. Now what's odd is that those pistons have no valve reliefs. So a 'right' piston could be installed 'upside down' on the other side and it would be the same thing.
On average, I move around 4-5 blocks a month from station to station. Some of these blocks are used out on the salt flats, and sprint cars. I've not ran into a single one with cylinder walls like that. The only difference is they are in to "freshen" up, on occasion fit new pistons, and have previously been machined here. There is a problem with the machine work, or someone assembled it after a bottle of bourbon....thats beyond a 6 pack.
 
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