blackeg

a while back i had a few threads on my b20b that was preigniting like a ****. finally took it apart and this is what the cylinders look like

.
now thats a 120,000ish stock b20b. tons of carbon buildup. the headgasket between 2 and 3 was compromised you can see wherethe pistons were being washed a bit. also the compression in 3 was 180 but high leakdown into the 2nd cyl. the other cyls had compression a bit more and less leakdown.

anyway a closer pic of the walls you can still see the crosshatch for the most part, but there seems to be some rust about 1-2 inches down in the bore.



the head is off for a cleaning/ new valve seals and a fresh valve lap. think i should pop the pistons out and run my 600 grit ballhone through it then toss it back to gether with new hastings rings or just let it ride

wreckeddc4

Do the hone and fresh rings. You will be happy you did. Otherwise, getting the head re done is almost a waste.

turbodcxbro

iTrader: (1)

Another vote for a quick hone and fresh rings! Use a ball hone and some WD40, about 10 strokes in each hole.

nealnanoHX

Yeah do a hone might as well. New rings and since it is apart get some 84mm ITR style pistons and new bearings. You will increase compression and have a nice fresh motor.

0Justin@Spreen

another vote on the hone and re-ring

bigG

iTrader: (6)

deck the block to

blackeg

well, rings are ordered so i guess that answers that.

ill check the block with a good straightedge, but i think the service limit is like .004 or some crap that i doubt it is warped past. white scotchbrite pads seem to clean up head and block surfaces real nice after a little brake cleaner removes the oil and grease

though i do have a perfectly good set of 84.5mm itr's on ls rods, this motor is going back together as bone stock as when it was taken apart. it is a spare engine in case i blow up the one in my daily driver so pretty much it will sit in my shed for a long time. (might spec it all out then pack it away still apart ready to go together quickly if i need it)

Rocket

This looks like pitting from the ring micro-welding to the upper cylinder. If it is, you'll need to bore and hone to the next oversize. Consult with your machine shop for an opinion.

blackeg

rocket your knowledge is top notch i would have overlooked that. the motor ran hot egt wise but not coolant temp. i did have plans to add cams and valvetrain to this motor but it never really ran right. might have to use those rs machines itr pistons after all...

spAdam

iTrader: (1)

I'd wait on the machine shop's determination before committing to keeping the stock bore. The RS pistons are a great option though if you decide to go oversize. I'm glad you found your culprit though, I know you were getting pretty frustrated with the thing.





**Shameless plug... I have some oversize PHK's on reconditioned ls rods ready to drop in if you still want to stay with a stock-ish piston. Check my sig.

EsotericImage

iTrader: (8)

I have a flex hone I used for my B20 if you plan on doing a DIY hone.

PM me if interested.

blackeg

i have 2 flex hones, a 320 grit and a 600 grit and used both with good success in the past. ill swing by the machine shop on monday take a closer look. if it has to go 81.5mm and i use my rs itr pistons then ill just have the machine shop hone it too. unfortunately im right in the middle of a full renovation on the only bathroom in my house so my time is not focused on car stuff for another week or 2