Your new bore will be 4.44

 

that would stink, seems to me that usually piston to wall clearance with a decent forged piston is around 4-5 thou.. this is certainly more than that.. shame too cuz it's a new high dollar engine.

 

Any scuffing on the cylinder walls?

 

here is a video of the issue

http://youtu.be/dP0XEpk2ZrA

 

Pistons are smaller at the top than at skirt where you measure them for clearance.

 

I understand that but if they have the correct clearance down on the skirt should i be able to make them move that much and if i can make that noise with my hands i wonder what cold startup sounds like.

 

The only cylinder to show signs of scuffing. you cant feel it with your finger

 

The only cylinder to show signs of scuffing. you cant feel it with your finger

That is a lot of wear and tear for just dyno time Some thing is not right!!!

 

I believe that if the block is filled you would add .002 - .003 extra because the walls will not grow as much.

 

I don't think its a lot. Like was said, you need to check it down in the bore somewhere around 1/2" up from the bottom of the skirt for example. Side to side will be worse becasue the piston has no skirt on the sides. It is truly only relying on the crown clearance.

 

Piston rock is normal, if those are 2618 pistons, for a blower set up, and filled block, your clearance should be more than .005

 

X2, and on a blower setup, try and run them tighter and you will have more to worry about them Piston rock

 

Probably not too high dollar with a flat tappet cam. judging by the shadows on the cylinder walls I would bet the final hone was done with out a plate.

Best to knock one out and measure it if it's of that much concern.

 

Wouldn't the heads not being on/torqued affect this also?

 

More than likely what caused it... no plate when honed then heads torqued on and ran...pulls the walls out of round.

 

If you are really concerned just pull the pan, take a piston out and measure it. Looks like its on a stand. Anything else is guessing. IMO

Corey

 

If you are really concerned just pull the pan, take a piston out and measure it. Looks like its on a stand. Anything else is guessing. IMO

Corey

He's right.

The piston rock doesn't look real excessive to me, but the only way to know is measure .500" up from the bottom of the skirt and see where you're at. That cylinder wall looks like it had quite a bit of heat & wear just from being on a dyno? I suspect it isn't completely round and likely wasn't even after it was honed the last time..

 

Diamond recomends .007 to .008 on forced induction street / strip . 2618

 

sorry .......

Minimum of .0055 for 2618 material

Street strip - power adder add .001 to .003 .

 

The pistons do that no matter where they are in the bore, top , bottom or middle. this engine was supposedly honed with torque plates but i'm beginning to wonder. there is some odd texturing in the middle of a couple pistons almost like corrosion and i suspect it might be from detonation. looks like it's time for a complete teardown and inspection dammit

 

Holy crap. How much dyno time was that?

 

Pistons are not ROUND at the skirt, they are egg shaped,the clearance at measuring point may be .0055,but the ring belt will be about .040 smaller and round,the cam grind at 45 degrees off center may be .005 to .015 smaller than at measurement point.picture an egg in a round hole.Bill C.

 

whats strange is how the scuffing is evenly spaced around the bore

 

All directly between the torque area's

 

it / THIS IS ALL JUST GUESSING UNTILL THE PISTONS ARE REMOVED AND MEASURED PROPERLY / ACCURATELY...
and then compared to the actual boresize with proper dial bore gage instruments

pistons CAN shrink / collapse..

rings can hang up and skuff

there are just too many possibilities..!!

the pictured cylinder appears to be worn...
that is A LOT for the amount of TIME that you have spoken about...

 

Are they the right rings ? Sometimes they have a shallow ring grove and do not take standard rings . Some take a smaller radial width .

 

This is what I'd be looking at. It looks like the piston is touching the cylinder wall in several places around the top. I'd bet it's got .170 rings in a .200 deep groove or something along those lines.

 

got the engine pulled down and the skirts are not black at all. many other issues with the engine though.

 

All this talk talk talk talk talk......put a stinking bore gauge in the dang bore and measure it. That size bore can use anywhere from .006" to .009" clearance for a 1000 hp 455.

 

bore size is irrelevant now, crank journals and snout wasted, bearings wasted, bores scuffed. besides that i dont own a bore gauge and am not hauling a junk motor to the machine shop to have bore checked.

 

I would post this over on v8buick.com to see what Jim Wiese recommends.

 

smart ass

 

I'm sure the bearings are wasted, Jim likes those tight bearing clearances!

 

junking the crank, block and bearings. pistons will get sold

 

if it had dyno time only, why were you cleaning carbon off the pistons? what fuel was used and top ring material. I know you said bottom end is junk, nut it might help someone else with this issue.