while installing piston2 i felt a bit of resistance and thought it would straighten itsef out if i kept tapping it...turns out bottom oil ring got loose anf flipped up scratchng two equal length marks from the deck down...its about at a 9 o'clock position looking at the block from the front...they are about an inch apart from each other...

its not so much a scratch but more of an abrasion....each of th scratches are about 15mm long and 1.2mm wide....they do not look very deep...maybe a couple thousandths deep max...


pretty much im just trying to save the block...if i put the piston in now it will definitely have more leakdown than id like to see....so now im wondering if i can hone out that single cylinder without issue....depending on how much i have to hone i may or may not have to get new rings...i already run loose tolerances on the rings since it is a nitrous motor...wondering how much a couple thousandths more ring gap may effect it... im currently at .021 .023....
i forget the conversion...is it for every thousandths increase of bore diameter ring gap will open 3.14 thousandths?


pretty much im just trying to salvage this block...i know its not going to run the best it would but it will get me by till i can afford to sleeve it....i dont think leakdown will be excessive...i measured the distance between the top of the piston and the first ring slot and its about 6.5mm...now consider that the scratch is about 15mm long...that leaves about 8.5mm of piston travel where the seal will not be true....i would assume te top of the pistons stroke is the most important time for ring seal, both on the compression and combustion stroke....but the piston does not dwell there for very long...just trying to gauge how bad the situation is for cylinder seal...

i know theres no way to tell until we measure exactly how deep the scoring is to see if it will be ok with a hone....but if a perfect circle is obtainable with a hone how important is P2W clearance? since i will be running that cylinder looser than the others....i just dont want it to create any sort of instability in the rotating assembly...

i was thinking maybe getting some sort of coating on the skirts of the single piston to make up for the excessive gap if necessary

hopefully that covers all the pertinent information, if anything else is needed ill do my best to give what ever information i can...

i can also take pics...

thanks!

 

dingleberry

 

anybody?

 

its hard to tell without seeing it but if you are going to try to salvage it i'd just run a hone through it real quick to break the edge in case the scratch protrudes into the bore. you just want to make sure the rings dont get damaged from the scratch.
then just assemble it and run it as it.

can you catch your nail on the scratches??

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by lohatch &raquo;</TD></TR><TR><TD CLASS="quote">its hard to tell without seeing it but if you are going to try to salvage it i'd just run a hone through it real quick to break the edge in case the scratch protrudes into the bore. you just want to make sure the rings dont get damaged from the scratch.
then just assemble it and run it as it.

can you catch your nail on the scratches??</TD></TR></TABLE>
thats what i am planning on doing....honing to the max(if need be) without having to overbore...
just wondering if there is an acceptable limit to p2w?
also if honing a single cylinder out will cause instability in the rotating assembly?

yeah you can definitely catch a finger on it...i will try to take pictures of it a little later...its not very pretty

 

they do it on boat motors all the time but then again were not talkin about a boat motor. i really dont see it hurtin anything as long as it is still in spec.

 

since its a nitrous motor i would just hone and assemble. i wouldnt do that on a daily driver but your gonna run the **** out of it anyway. i dont think it will take away any reliability, just hopefully that cylinder wont leak alot

 

yeah i hope not.....hopefully ill have some time off today to go down to the machine shop and do some measurments....tools keep coming up missing at our shop and its starting to really **** me off everytime i need something and its not there....