Engine Bore

[wildphil]

I have a couple of questions for some of the engine builders on the board.

I just picked up my engine block from the machine shop.

Two of the cylinders have scratches in them. They look like the scuff marks that pistons get on the skirts. On one cylinder they can barely be felt with the fingernail. The other cylinder has more scratches and are deep enough to catch your fingernail in the scratch. But just barely. Is this to deep of a scratch and something needs to be done about it?

My other issue is the honing. The cylinders to me don't look like they were honed When I dissemblance the engine I could still see light hone marks. And to me it still looks the same. Should the hone marks make it rougher and not have any type of smooth texture? Or can it look smoother with light hone marks?

I tried to get pics but they didn't come out well.

I just couldn't get a good pic of the scratches.

Here is a pic that shows the scratch a little better. But it looks worse in the pic than it really is.

The hone marks look better in the pics than they do visually.

 

[SYCLONE#1531]

Re: Engine Bore

you shouldnt beable to feel any scratches with your nail. It looks like someone used a dingle berry hone on it which will leave hone marks without material removal.? Are you sure that they actually bored it. From my experience with my fathers cnc Sunnen hone you will be left with a nice smooth scratch free surface. No vertical up down scratches.:2cents:

 

[wildphil]

Re: Engine Bore

you shouldnt beable to feel any scratches with your nail. It looks like someone used a dingle berry hone on it which will leave hone marks without material removal.? Are you sure that they actually bored it. From my experience with my fathers cnc Sunnen hone you will be left with a nice smooth scratch free surface. No vertical up down scratches.:2cents:

Thank you for replying. This time it was not bored. The block was bored 2k miles ago to .030. I noticed low oil pressure. So The engine was tore down and the bearing were gone. The crank had to be reground from .010 to .020. The guy at the machine shop was supposed to check the block out to get it ready to assemble.

As I remembered from years ago when I rebuilt engines in the old days. The honing marks were more rough.

And those scratches while not deep, They can be felt with a fingernail.

 

[Don W.]

Re: Engine Bore

Couple things. It's really a judgement call on the scratches. Without seeing them , emmm ok, leave them. The alternative is prolly a re-bore? Those hone marks (or whatever you call 'em) are NOT at the correct angle and may not even be deep enough. Anyway, angle is to great. For example see:

http://www.brushresearch.com/engine-hone.php

 

[RealFastV6]

Re: Engine Bore

If you didn't bore it, then those are from your pistons. Honing it isn't going to remove anything like that.

I guess in the end it's your call - do you want to buy pistons or not?

 

[wildphil]

Re: Engine Bore

Thanks everyone. We have been discussing this over on chat. It looks like the scratches are low enough in the bore to not cause a problem.

 

[HopnDude]

Re: Engine Bore

I've got a question, if I may pitch in on the subject.

First off, the guy who helped me piece together my engine build, and did the machine work, did a A1 job! I didn't take any pictures, but got to see it after the machine work, it had to be bored .03 over, after he did the "dingle berry thing" sounds funny, but I know exactly what your speaking in reference too. It had the cross hatchings, but was baby butt smooth!

Now my question!
If someone had to do more of a bore than they'd like, would it be a good or bad idea to sleeve the block?
1) Opinions about this
2) Technical good/bad from doing this

 

[Don W.]

Re: Engine Bore

Now my question!
If someone had to do more of a bore than they'd like, would it be a good or bad idea to sleeve the block?
1) Opinions about this
2) Technical good/bad from doing this

:2cents:My machinist told me that sleeving these blocks distorts them (or at least the adjacent cylinders) enough that you have to bore the other cyls just so everything is straight. IOW it's virtually impossible to bring just one cyl back from injury. So I was told anyway.

I think that the reason is the relative thinness of our cyl walls compared to "the old days" when sleeving was more common. Also sleeving requires the block be decked. So, as I understand it, it ain't worth it.:2cents:

 

[HopnDude]

Re: Engine Bore

Just now thought about it, but to add to my question;

Would block material greatly effect a sleeve job? How it's done or how long it last.

 

[Don W.]

Re: Engine Bore

Here's an interesting site that explains things. Dave, I'm not entirely sure what your machinist means by glue. Sealant maybe? I don't think the entire cylinder is removed. This would reduce the strength of the block considerably and require both a sholder at the top for the sleeve to sit on and some sort of sealing mechanism at the bottom. I think you're thinking of a wet sleeve like used in big diesels.

Block material? You mean iron as opposed to aluminum? I believe most iron blocks are similar excepting detail mix of the raw material like nickel content.

http://www.popularhotrodding.com/enginemasters/articles/hardcore/0603em_block_sleeving/viewall.html