This engine build has been nothing but a pain graemlins/angry.gif !!!
The problem on the table now - two of the pistons are making a "scuffing noise" at the bottom of the stroke (starts about 3/8" before the skirt comes out of the jug) There are also slight scratches on the coating of the Speed Pro Pistons.

There are no marks whatsoever on the cylender walls,& we have removed the pistons to double check the installation of the rings...

Does anybody out there have any idea what could be causing this?? Could it be a bad bore job? Or could it just be from the bore being tighter at the bottom of the jug?

Any help would be appreciated,& thank you in advance.
Scott Salerno

Take it back to the machine shop and have them check the bore and piston size.

Did your machinist match the bores to your piston set? Each piston should be set to a specific bore if he's thorough.

If this is your first engine assembly and you spent $3000, I'd be nervous too. Do you have the instruments to check bearing clearances, crank end play, piston to wall, piston to valve, deck height, etc.? Just my opinion, but I'd pay the machine shop a couple hun to assemble it and make sure everything is right as they go. I'd wait and assemble a junk smallblock as my first to gain some experience and confidence. That way the machine shop would be more willing to accept responsibility if something goes wrong and your wife won't leave you if something very expensive happens after you assembled it. :D

Well this morning I went to the machinest & dragged him (actually he offered to come) over to my house to checkk it out. We removed the piston in question (# 5) & measured the bore. It was SLIGHTLY larger in the bottom 1" of the jug.

He said it would prob. be OK but he would feel alot better if I took it all apart so he could re-hone that cylinder.

I know he did not bore the block untill he received the pistons, so I assume that was to match the bore exactly..

The rest of the engine was as smooth as sick,& he said that what I did looked real good. However all he could offer was his appoligy & to correct the problem. he did say that this is the first time he has ever had this problem(my luck)

The part that hurts the worst, is after having a clearence prob with the rods & having to grind out the block. This is the second time that I have to tear down & it will be the third time putting it all together....But then again, isn't that the fun of having a muscle car...

Thanx for the help,
Scott

Look at it this way after three times you can do it with your eyes closed.

I havn't heard the word "jug" used for a cylinder in a long time.
I must be thinking of Girls Gone Wild too much graemlins/clonk.gif

Scott,
One thing that we do, that I have not seen many other machine shops do...is to take a sanding roll on the die grinder and run it around the bottom of the bores to break the sharp edge that results from boring and honing. We come in from the top and just make a quick pass around the bottom of the bore. I personally think that it reduces a lot of the initial scuffing that you are seeing on the skirts. I guess we got in the habit because we always do it on engines we build ourselves. You could do the same thing with a fine file or some emery cloth. Its one of the small details that make a big difference in overall reliability.

Originally posted by ssal396:

The part that hurts the worst, is after having a clearence prob with the rods & having to grind out the block. This is the second time that I have to tear down & it will be the third time putting it all together....But then again, isn't that the fun of having a muscle car...

Thanx for the help,
Scott Scott, You are way ahead of the game. Lots of people get so geeked when they get their block back from the machine shop that they HAVE to assemble it THAT weekend! The next weekend you see them posting about some serious engine trouble ;) Three assemblies is a hassle, but I think you'll be smiling when you fire up the finished product. graemlins/thumbsup.gif

Mike

Thats a great idea Bill.
I whish I would have thought of that on my last rebuild. When I tore it down I noticed scuffing in the bottom of the cyllenders. I though the piston skirt and bore diameters were wrong, but they measured right on. I bet that is what it was.
Well, next time... smile.gif

last night I tore the block down AGAIN, I figured while it was torn down I'd take the dye grinder & put a slight chamfer to the bottom edge. I just hope when the machine shop re-hones the cylenders it doesn't create another edge down there.

PS
what do you guys think about the bearings after three assemblies. Or for that matter, the rear main seal. It's been siliconed together twice already...

That sucks Scott, was hoping to see you at the Brunswick cruise Saturday!!If you need any help give me a shout. Mike