Need advice cylinder scratches

[A408Cuda]

From what I can see, that looks perfectly normal and standard from all I have ever seen. A couple of times I have had to tear down engines with low miles for inspection (like a race engine that blew out all the oil and I wanted to look at the bearings), and the cylinder walls looked just like that. I don't see anything like overheating or scuffing or rings momentarily seizing in your pix. Actual problems like those make the wall marks look a lot more serious.

Leakdown test? That will be your real objective answer if you are not comfortable with opinions or others' experience.

Thanks I appreciate the advice, im going to run it and see, they just made me a little nervous, being this engine was pricy and the only run time was the dyno that I didn't witness.

 

[moper]

They did a crap job of cleaning the bores, or some debris found it's way between the piston/ring/bore surface. It would bother me, but I wouldn't take it apart for that. I've found worse in engines with a lot more miles... One 360 I took apart had been rebuilt but never run. Good thing too - 3 of 5 main bearing "bottom" shells were install in the "top" saddles in their respective bores...

 

[krazykuda]

Ok so ill try to keep this short, Ive been building this old Cuda for about 5 years now and I'm almost ready to fire it up. I had this 408 LA built about a year ago, I had to swap oil pans because the Moroso It came with sat to low to the ground. when I pulled the pan I could visually see up and down scratch marks in cylinders 3,5 and 4. I couldn't really feel the marks with my finger but they were there, Unfortunately I didn't have the for-site to take pictures. The engine was only run for the dyno and I was pleased with those numbers. (I didn't see it run.)
After much digging around the site I've come to the conclusion that there probably from the builder failing to clean up the ends of the rings (debur). At the time I told myself it would be fine and just to run it and see how it goes. But I cant seem to get it out of my head! Is it something i should fix before I start it up. I know what everyone is going to say. Send it back to the builder, but logistically that's a nightmare for me and I'm not sure I'm willing to wait another 6 or 7 months for them to get to it and its a couple states away. So the question should I go ahead and run it and see how it goes? What damage do I risk by running it? Would the smartest thing be to just tear it down now? 408, fully forged, KB pistons, 10 to 1 CR, eddy heads, Howards cam.

I talked to the builder, im going to fire it up and run it for awhile then do a compression test, they said they would stand behind there product, so worst case scenario, ill have to pull it and send it back to them. Sucks but at least I have a little piece of mind.

If you couldn't catch your finger nail in the scratches, then you should be ok...

Also, as long as the scratches did not make any metal proud (higher than the metal surrounding it), you should be ok... (If the scratches went below the surface and not above it and not too deep, you should be ok...)

The worst that can happen is you can get some blow by...

I would do a compression check, and/or a leak down test to see if it is affecting the sealing of the rings at all if you want a piece of mind without tearing the engine down again...

If anything, as the cylinder wears, it should make the scratches smaller and less affect on performance...

Keep in mind that combustion is pretty instantaneous and there is very little time for the small scratches to leak unless they are too deep, and if they are you should have been able to catch your finger nail on them when running it across the scratch.... Run the finger nail perpendicular (90°) to the scratch to check...

We used the finger nail test at the engine factory to tell if we could run with the issue or not on cranks, head surfaces, cylinders, etc....

 

[krazykuda]

If you couldn't catch your finger nail in the scratches, then you should be ok...

Also, as long as the scratches did not make any metal proud (higher than the metal surrounding it), you should be ok... (If the scratches went below the surface and not above it and not too deep, you should be ok...)

The worst that can happen is you can get some blow by...

I would do a compression check, and/or a leak down test to see if it is affecting the sealing of the rings at all if you want a piece of mind without tearing the engine down again...

If anything, as the cylinder wears, it should make the scratches smaller and less affect on performance...

Keep in mind that combustion is pretty instantaneous and there is very little time for the small scratches to leak unless they are too deep, and if they are you should have been able to catch your finger nail on them when running it across the scratch.... Run the finger nail perpendicular (90°) to the scratch to check...

We used the finger nail test at the engine factory to tell if we could run with the issue or not on cranks, head surfaces, cylinders, etc....

Run the compression test dry first, then put two squirts of oil in the cylinder and run it again and see if it makes much difference... That will give you and indication if the rings are sealed or are leaking some...

 

[AJ/FormS]

I kindof agree with Moper
After I built my car, and spent all that money, I couldn't justify running it just in summer. So every fall I would swap in a smogger-teen for the winter. Then I stripped that 360HO down for a look. For the first three winters, I always found potential troubles and upgraded as needed. But the one thing I never found was scratches like that in the cylinder walls. I did that two more winters, without finding any more issues. After that I left the 367 in there, and made it a summer car, because by now she had accumulated enough miles, and I found myself with enough disposable cash,to justify that.
I also agree with the leakdown test. But I would compare the leakage at the bottoms of the bores, with leakage somewhere in the scratch zone. To do this you would have to back off the rocker gear, and you would have to figure out how to anchor the crank in the part-way-up position. And you would not be able to use very much pressure because at 80psi, in a 4.04 bore, you will be generating over 1000pounds of force on top of the piston; I suggest 30ish psi and wait for the air pressure to settle down. I would not use a per-cent gauge but rather use a compression pressure gauge. Because of the small pressures involved,accuracy in reading will be very important. 30psi is ~360pounds of force, and 40psi is just over 500, so use a big fat bar, and do NOT try to hang on to it. I have used the balancer bolt at 30psi, and the bolt survived. I used a valve on the airline to engage the pressure softly.
It's a lotta work, and the results are only as good as your accuracy in reading. for instance, when converting your numbers to percent; a 1 psi error in reading amounts to 1/30=.0333 or 3%! So the point is not to let the percent numbers scare you. Rather the psi differences from bottom to wherever you stopped, and the cylinder to cylinder variation. Did I mention it's a lotta work?
If you couldn't catch a fingernail, as mentioned, I agree with everyone who says just drive it.

 

[mullinax95]

Seems like as small as those scratches are I would run it.

I would be hesitate to use that engine builder again.