LLY disection

[Cougar281]

Got the top of the motor apart tonight. The #5 glow plug (the one I couldn't get out when I tried to do a compression test a while back) came out with no issue and the tip was fine. Interestingly, none of the pistons show the obvious star pattern that I've seen in pictures of other disected motors, despite the fact that I've run some "warm" tunes.

For the most part, the cylinder walls don't look bad, although some of them have some fine lengthwise scratches that I could see but not feel with my fingernail.

Attached are some crappy pics from my crackberry... I'll probably get some good hi-res pics with my DSLR tomorrow and post them up.

 

[Akdiesel]

Did anything fail?

 

[dmaxfireman]

if you wipe down the piston decks with a rag and maybe some paint thinner you will most likely see at least a faint flower pattern. i have seen it on all the motors i have torn down stock or tuned.

 

[Cougar281]

Did anything fail?

No, it was running fine when I pulled it for the LBZ swap. I'm going to pull the oil pans and timing cover, swap the crank reluctor and cam reluctor, and roll it over and inspect the bottoms of the pistons to make sure I don't see any cracked skirts. Assuming everything looks ok, It's going to go back together with a LBZ top end and going back in the truck so I can take my time building the LBZ shortblock.

 

[Akdiesel]

Right on man...can't wait to see the thread on that so when I get ready to mine I'll have some good info to go off of

 

[Cougar281]

Here are some pics.... Looks like #4 has been seeing some coolant.

What's with the top edge of most of the pistons? Is that normal? I'm not sure if they're pitted or if it's hardened carbon....

These where taken before I blew the cylinders out with compressed air or even turned it over, so there's some debris from the removal of the heads.

Is there anything about the pistons that screams take it all apart? Motor was running fine when I pulled it.

 

[duratothemax]

looks good Dave. Did you check piston protrusion for bent rods?

 

[Cougar281]

looks good Dave. Did you check piston protrusion for bent rods?

Not yet..... Probably this weekend.

If you look at the top of _MG_3144, what's the deal with the "flakes" between the piston & wall? IIRC, they broke away like carbon, but I thought they where odd _MG_3160 shows what I was asking about.... Looking closely now, it does look more like buildup (such as carbon) than pitting. Is there any special cleanup I should do on the pistons before putting it all back together? Maybe get some of the white Roloc discs and clean them, or just leave them be?

 

[Cougar281]

.0085 - 2 1 - .0065
.0090 - 4 3 - .0095
.0095 - 6 5 - .0135
.0095 - 8 7 - .0065

According to the GM spec (.0039" max variance), either I have 7 short rods, or I somehow goofed on #5...

 

[duratothemax]

so they had positive protrusion right? At TDC the pistons were sticking up above the deck?

 

[Cougar281]

so they had positive protrusion right? At TDC the pistons were sticking up above the deck?

yep.... by the amounts above.

 

[Cougar281]

I re-measured #5 today and the most protrusion I could get was .010, in which case, all would be within spec. Maybe there was a smidge of grease under the "top" edge of the mag mase casing the readings to be a bit off on that one.

 

[TheBac]

Everything looks and sounds good, Dave. C gaskets?