I finally removed my motor to tackle an oil consumption problem I have been having. To my surprise, the pistons look almost like the day I installed them. They were oily and are coated with a oily residue but not a carbon buildup that I thought I would see. remember I am burning like a quart every 150 miles or so. It looked like some oil was seeping in through the exhaust valve stems on 1,7,2 and 8 cylinders but not that much. There was slightly more carbon on the backs of the exhaust valves but not bad at all. The cylinder walls still have the crosshatch hone pattern on them and they look very smooth with no score marks. I have yet to pull a piston.

Here are some pictures:





What surprised me is the amount of piston rock I have. Both fore and aft plus up and down (towards lifter valley and away). I can't find my feeler gages but I would bet it is .020 to .030". My build sheet states the piston to wall was .003". I know these pistons have short skirts but I find it very strange that they rock so much. They are SRP pistons set up for a 5.85" rod. Click the link to look at the video.
http://s162.photobucket.com/albums/t...t=P1010022.flv
I plan on pulling one piston and re-checking bore diameter and piston to wall clearance. I hope all I need to do is put in a new set of rings with a standard tension oil ring. Is this amount of piston rock normal?

 

does this block have any hardblock ??

 

No it does not. I built this when 396 motors where just coming on stream. More Performance did the block work and short block assembly.

 

I pulled number one piston and it looks good. I removed the rings and placed the piston back in the bore and seems there is alot of moving around. The piston measured 4.0288" by the guy at MORE that assembled the motor. He honed each cylinder to get the proper clearance based on what the piston dimension was.

The rod bearing looks brand new with no copper showing.

 

Try to mic the piston and then the cylinder bore to get an idea of how much clearance there really is. See if it measures out of round a bit.

 

Too bad More Performance isn't in business anymore. How did you break it in?

 

I was just thinking the same thing. Looks like a lot of blow by to me. Maybe those rings never got seated in properly?

 

Id get a measurement, if you really had 30 thou clearance you would have some serious racket going on under the hood.

 

Plus, you'd now have collapsed skirts.

What's the ring land measure? And ring end gap?

 

Heh Jason. Nice to see you ripping it apart. What's the plan with the motor? Thinking about going back to the miniram?

 

Is there were any plugs oil fouling,

 

Just to throw a comparison of engines, here is my MorePerformance 396 after about 3000kmiles. Mine was More 118. And I burn about a quart a 1000 miles, which I believe is due to rings being low tension. It was broken in with Dino oil and broken in hard. And the build sheets.
First Pics I cleaned the psiton.




Notice the timing chain

 

Steve,

Your pictures look identical to mine. I still have yet to measure the piston to wall clearance since I have to borrow the micrometers. However, If I square up the piston in the bore, and try to move it side to side without rocking it, it does not move. So probably the clearance is correct and the movement of the piston is piston rock.

The rings are Speed Pro and my end gaps are .017" top and .015" for the second ring and I think my oil rings are low tension but I can't remember. Is there anywayto tell? My piston to wall clearance was .003" and honed with a torque plate. Finish was a 625 three brush hone.

I drove the car hard right out of the box with no special break in procedure. The second ring interestingly does not have the full shiney surface on it. One two sides it does but on the other sides it is only touching about 50% of the ring. I too think I have alot of blowby because my oil turns black almost immediately.

After I confirm all my dimensions are correct, I'll re-hone the cylinders and install new rings. I remember Mike at MORE told me he started using a different top ring or second ring to combat oil usage.

 

I dont feel so bad about my stock bottom end having about half that movment in the pistons now!! My bores also have a crosshatch on them and are exceptionally smooth, im just shy of 100,000 miles. I dont know what the history of the engine is before i bought it @ 81,000 miles though, the top end was all pulled off at some stage before i got it (although i did it all again myself and its not smoking now that the valve guides and stem seals are sitting still)

Does anyone think there is a good chance my block my have been honed at some stage or is the crosshatch pattern normal from the factory? There is abit of movment in the pistons, but not as much as that, probably less than half.

 

Unless you have the build sheet, I dont think there is a part number on the rings. My build sheet shows the part number for the rings, and More Used low tension oil rings unless you requested something else, so the horspeower was higher.
I would highly recommend standard tension rings as there are great ones out there. JE makes them too, and since you have either JE or SRP pistons (same company, SRP are a little tighter clearance), I would get ahold of them and get rigns to fit your pistons and follow there honing recommendations. And Break it in with Dino Oil and run it hard. There is a procedure on this forum where a guy swears by his break in procedure, and it works apparently. Its like 3-4 dyno runs, which seats the rings very well.

 

NEVER!

 

Steve,

I have the SRP pistons. They look just like yours with a -14 cc dish and are for a 5.85 rod. I was thinking the same thing you were about calling SRP and asking them. The pistons are set up for 1/16, 1/16, 3/16 rings. I have the build sheet and it does not say low or high tension oil rings. I supplied file fit Speed pro rings to MORE (I was going to build the motor myself but decided to have MORE assemble it). I remember that Jesse (the guy that assembled the motor) called me and said I supplied him with standard tension oil rings and he recommended low tension rings. I think I told him to use low tension but I can't remember. I don't think there is anyway to tell which rings (std or low) right now.

 

the only time you would want a low tension oil ring is if was an all out drag car and with a vacum pump other wise you have very bad oil consumption problems hell i have reg tension oil rings in that 572 bbc 14.1 comp motor i built making just a tad over 900 hp that runs high 8s on the motor

 

The low tension are what people are telling me is the reason I use oil. I bet you change to standard and you will not use oil like you havebeen, especially with a proper break in.
Here is the procedure
http://www.mototuneusa.com/break_in_secrets.htm

 

I didnt know any better and should have changed them the last time the engine was out. I will pull it again and change rings soon I hope.