Cylinder wall problems ( never seen anything like it)

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fishmens67 said:
block is scrap metal. you won't clean those bores up with a hone. never seal.
looks like the bores were rust pitted before the last trip to the boring bar.
didn't cleanup then, won't now.
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There were no rust pitts in the bores before and yes the block is junk, but what caused this to occurred??
 
My guess is that you have pin holes in the cyl wall from years of rusting on the inside. aka water jacket side. When you honed it, it hit that critical thickness and stared to leak coolant/water. into the cyl/combustion chamber.

I bet, that if you took a flapper wheel to the dent in the bottom of the bore........You would go thru the cyl wall. aka paper thin.

Hope you find a sonic tester
 
Cudafever said:
My guess is that you have pin holes in the cyl wall from years of rusting on the inside. aka water jacket side. When you honed it, it hit that critical thickness and stared to leak coolant/water. into the cyl/combustion chamber.

I bet, that if you took a flapper wheel to the dent in the bottom of the bore........You would go thru the cyl wall. aka paper thin.

Hope you find a sonic tester
Click to expand...

Exactly what I was thinking ! If I don´t find a sonic tester I will buy one just to find out.
The walls also has bold spots with no cross mark left all over the place, so it has to be extremly thin and out of roundness.
 
The block is shot right? why not grind on it or better yet get a small ball peen hammer :violent1: and give them dents a little tapping.

Dime to donuts, it brake through...............
 
This engine sits. Anything that sits will see condensation. If you have a thin spot on the water jacket side of the block, it will pocket, especially in an engine with infrequent use and condensation.

Your bore diameter and skirts check out fine. I'm running .0015"-.002" clearance.

The groove in the piston is an accumulation groove to help seal between the upper and lower compression rings. It acts as a buffer and will only cause any marking on the cylinder walls, due to trapping moisture between use.

65SignetSweden said:
No my instructions says it should be the same, it also says so on kb:s homepage.
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This is a giant red flag for me. Why;

http://www.kb-silvolite.com/article.php?action=read&A_id=32

I'm running a street engine and the requirements of my engine put the end gap at .030" with the exact same piston.

Those pistons, while being hypers, also have a much higher top ring groove, closer to the heat and they will absolutely need to be file/ gap fitted, so the heat won't close them. The bottom rings are ok to install without additional gap.

The gap that you gave is the exact gap that my 2nd ring has.

My guess is that with every pass, you are building heat from tight ring gaps closing, distorting the already distorted cylinder walls under load and it will only make problems worse, each time the engine is run this way.

What I think the cause of your trouble is;

Shoddy block, bad wall thickness/ abused/ pitted water jackets, causing distortion on the inside of your piston wall caused by... Tight ring gap giving excessive heat/ warp/ pitting/ pocketting to an already stressed block.

They may feel smooth when the engine is out of the car and examined, but I'll bet you that is a different story when it's running.

I think if this engine saw anything, other than drag strip pass use, you would have broken a piston.
 
Interesting thread. I went .032"first ring,.036" second,on a KB356'ed 408. Instead of buying a sonic tester,why not a early to late 70's block?.......
 
Yeah, they called N/A applications ring gap factor in at .0065" and Tow/ RV/ Boost .0080" I qualify for the prior, but it will see mountains once in a while, so I went .030" Lucked out on the '73 block. It's never been overheated or run on water. Original shim gaskets looked great, decks checked out with a straightedge even, when it came apart, so I got a green light to just bore/hone after looking at it.

Why did you go .036" on 2nd? Do you mean .036" top and .032" bottom?
 
Okey I finally took the thumb out of my a## and checked the engine block.
I took a Hammer and cracked the cylinder walls in big pieces.
The thinnest spot I could find was 0.110
I then took my new sonic tester and calibrated it with the cylinder wall pieces so it would be as accurate as possible and I did not find any thinner spot then 0.110". So I think that the thickness was not the issue, and all the discoulor on the walls I think was caused by the octane booster I´d had used ( never thought of that before)
Have a friend that had the exact same issue but he ran his engine on E85 fuel.
Again thanks for all the input.
 
The wall pattern and discoloration in pix 1 and 2 looks like 'gas washing' on the cylinder walls; the oil is being washed off by something, perhaps excess gas or alcohol or chemicals; the wall is heating due to something. This type of discoloration will happen due localized heating of the wall due to the oil being washed off. How were the rings?

What is in your fuel? I can understand the E85 perhaps washing off oil.

Can't say anything on the 'dents' in the wall....that is a new one? Or perhaps a really bad case of the oil washed off.
 
You have multiple problems-
Block wasn't honed with a torque plate, preventing the rings from sealing, as seen in the ring wear patterns. Those bores move .002" with a plate on them, using up any effective clearance the piston might have had.
IMG_0238.jpg


and seen on the piston
IMG_0253.jpg


Along with being way to fat at idle and sucking oil somewhere IMO.
 
I agree with above post ^^^ and I also feel it was dumping fuel into the cylinders as well. too much fuel pressure or bad float seats in the carb or both, ... you said "hard to start"... sounds like it was flooded. so the getting worse each run was all that fuel washing the oil away, rings not seating, compression getting worse and worse.

what did the spark plugs look like? just curious

65SignetSweden said:
Do you guys think to much rpm could do this. The last run at the stip was the worst, the engine was very hard to start before I was going to warm the tires ( has never been hard to start before ) I started in 2 gear and reved it to 7000rpm as usual and after the burnout the engine started to run like a bag of nuts, shut down on cylinders and so on.

But when I lined up against the tree it started to go on all 8 again so I thought what the h# and ripped of a bad 12.88 @ 103.1 but a decent 7.98@1/8
After that I got home and made a Leakdown and compression test And the readings were all over the place so I took it apart and found the discoulor and dents.
Click to expand...
 
Yes the car did flooded the last time out and only fired on 5-6 cylinders after the burnout, but it cleared right up just before I staged. Mmmm sounds like the last burnout nailed the last nail in the coffin.
Never took the sparkplugs out on the track, I just loaded it up and went home, but before I did the leakdown test I had it warmed up and it started easy and runned like normal and the plugs looked good.

moparlover said:
I agree with above post ^^^ and I also feel it was dumping fuel into the cylinders as well. too much fuel pressure or bad float seats in the carb or both, ... you said "hard to start"... sounds like it was flooded. so the getting worse each run was all that fuel washing the oil away, rings not seating, compression getting worse and worse.

what did the spark plugs look like? just curious
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Hello Motorworks. Don't know if a torque plate was used but yes the bores is out of roundness big time. The idle af. has always been at 13-13.5 and the plugs looked good. af. at full throttle 12.2 -12.7 .

CPMotorworks said:
You have multiple problems-
Block wasn't honed with a torque plate, preventing the rings from sealing, as seen in the ring wear patterns. Those bores move .002" with a plate on them, using up any effective clearance the piston might have had.


Along with being way to fat at idle and sucking oil somewhere IMO.
Click to expand...
 
Okey gents, lets sum up.

The causes:

1. Bores out of roundness ( lack of torque plate? ) All the scars and bold spots.

2. Gas washed the oil of the walls ( flooded last burnout )

3. Discolour on walls made by heat (no oil on walls ) and chemicals in octane boosters.

4. Dents with white rings below piston rings at the bottom in cylinder walls = MYSTERY

Does this sound right?
 
Don't ever have that machine shop do work, or build you another engine. I would say 90% of your problems started there, by the looks of the inside of that thing. But your tune was also off as well, big time. Improper ring seal and piston/wall fit most likely attributed to that though.

Find a new/good machinist, and assemble it yourself. ;)
 
I have assemble all of my engines my self. The only ting I can´t do my self is honing and balance a rotating assembly. I now have an other shop that doing all of my honing and balancing.
And my tune was not off ( no pinging, 12.2-12.7 af. ,plugs ok, timing 35 deg)
I strongly think that all of this damage occured at the last race when the car started to go rich and flooded at the burnout. I have had this engine set up for 7-8 years now and has always tuned with Wideband af meter.

nitrojunkee said:
Don't ever have that machine shop do work, or build you another engine. I would say 90% of your problems started there, by the looks of the inside of that thing. But your tune was also off as well, big time. Improper ring seal and piston/wall fit most likely attributed to that though.

Find a new/good machinist, and assemble it yourself. ;)
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7,000 RPM doing a water burnout! With virtually no load on the engine! That will do nasty things to it. Just like revving it up to 7000 in neutral. 4500-5000 is my max with my NHRA stocker. But that's just me.
 
well I have a manual trans and no linelock so the car will jump forward a little bit before I can hold it still, and it´s no water there(very small waterbox). I have to almost floor it to hold the rpm between 6000-6900. I can´t hold it perfekt still and car want´s to move forwards, this is in 2 gear with 4.30 in the rear. physixx what is your engine and driveline combo?

physixx said:
7,000 RPM doing a water burnout! With virtually no load on the engine! That will do nasty things to it. Just like revving it up to 7000 in neutral. 4500-5000 is my max with my NHRA stocker. But that's just me.
Click to expand...
 
65SignetSweden said:
I have assemble all of my engines my self. The only ting I can´t do my self is honing and balance a rotating assembly. I now have an other shop that doing all of my honing and balancing.
And my tune was not off ( no pinging, 12.2-12.7 af. ,plugs ok, timing 35 deg)
I strongly think that all of this damage occured at the last race when the car started to go rich and flooded at the burnout. I have had this engine set up for 7-8 years now and has always tuned with Wideband af meter.
Click to expand...
I am thinking this too. With the high rpms and the associated reciporcating stress on the pistons, plus the sudden heat input of the burnout, it would not take much oil loss on the cylinder walls to do this. The wall discoloration is the clue that I have keyed in on that says gas-washing.

Just one dumb thing to check is to make sure that the piston/cylinder oiling outlets on the rods are pointed in the right direction. I assume this engine has them.....And that the pistons are oriented right and not mounted on the pins/rods 180 degrees out. I saw the 'dents' on the cylinder walls and wondered of the pin offset was backwards. Not that I know it would cause that....just all that came to mind.
 
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