Cylinder markings (1 Viewer)

[middlecalf]

So with my new top-secret NSA spy camera from China, I spied on my ‘64 F135‘s cylinders while they were sleeping, and came across these markings on the top. Any ideas as to what these are (all 6 have similar markings). OEM, aftermarket? I have no knowledge of engine’s history.

 

[SteveH]

All 6? That makes it less likely that it's a broken spark plug electrode clattering around inside.

 

[middlecalf]

Yeah the first one I looked at I thought that same thing. Then after seeing similar markings on all six cylinders I thought, wow, that was one busy spark plug electrode, and very artistic .

Maybe those are Japanese markings?

 

[fyton2v]

I think everyone should take the time to have their pistons engraved.

 

[Steamer]

Jeeez! Looks like one of these was involved.

 

[Pitter Patter]

So many questions but, I will start with how is the compression? Something obviously got in there. If it was just one piston then I’d suspect there’s a broken ring land that allowed part of a ring to travel up but you should see that on your inspection. Being on all 6… my best guess is little Jimmy put rocks in the engine for fun. In all seriousness, I’m curious how is the compression?

 

[Pitter Patter]

First photo is a new 2F piston crown, second is a 1FZ-FE when I had to do an emergency head gasket replacement. The condition of the FZJ80 piston is what you want to see (granted it was cleaned from all the coolant in the cylinder). Something was definitely bouncing around inside the engine at some point. It’s possible that a PO resolved the issue and put the pistons back in because I don’t believe they are readily available anymore. Let us know what you find, I’m curious. Pull the head, it’s an easy job on a 1964

 

[mrboatman]

Something was bouncing around in those cylinders. And its still running!!

 

[3_puppies]

I'm thinking it's all part of the Davinchi? code.

 

[middlecalf]

@Pitter Patter compression is all good. Still runs pretty good with a fair amount of oil usage. Here’s the history. Started low, now not bad. But maybe it’s all that oil?

But I’ve become suspicious of the effectiveness of compression tests. There’s a recent thread where a member has a hole in one of their cylinders and it still measured 146psi!

 

[middlecalf]

Cylinders are aluminum alloy and cylinder walls/sleeves are steel? Wondering why the walls look unmarked (or at least not grooved).

Vacuum is good and steady, so I’m not missing anything to do with valves.

Yeah heads coming off - at least, maybe the whole kit and kabootle .

 

[middlecalf]

Possibly dents from valve interference that might have been fixed since now it’s running, per Cameron (Mosely Motors)

Maybe those dents add turbulence in the combustion chamber and I’m getting some extra horsepower with better mixing of fuel/air vapor. Yeah, I’m sure that’s the ticket.

 

[middlecalf]

But how does this happen in a non-interference engine? All the valve springs or keepers break at the same time?

 

[pjohnson]

Maybe some sort of debris down the carb that finally worked its way out the exhaust or was removed at the same time as a head gasket/valve job?

 

[Skreddy]

But I’ve become suspicious of the effectiveness of compression tests. There’s a recent thread where a member has a hole in one of their cylinders and it still measured 146psi!

I am guessing when that piston is removed, the top of the piston above the ring is broken, but the ring is still in tact, which is what’s maintaining compression on that cylinder.

 

[peesalot]

Something got into that hole, bounced around a bit and got blown out or pulvarized.

 

[3_puppies]

Maybe some sort of debris down the carb that finally worked its way out the exhaust or was removed at the same time as a head gasket/valve job?

Something got into that hole, bounced around a bit and got blown out or pulvarized.

the OP stated that all 6 look similar, I've seen one like that but not all 6

 

[pjohnson]

the OP stated that all 6 look similar, I've seen one like that but not all 6

That's why I think it was debris down the carb, distributed to each cylinder.

If OP takes the head off, it will interesting to see which cylinders show more markings than others.

 

[middlecalf]

Here’s link to pics of other cylinders posted in my build thread. Cyl 6 has the least. Pics don’t show the whole cylinder, hard to do in the constrained space, but they all do have marks.

So this is fun. Got my new top-secret NSA spy camera from China, 5mp of pure delight. Here’s pics (won’t post boring videos, all the cylinders kept their clothes on):

Cyl 1
View attachment 2973520

Cyl 2
View attachment 2973521

Cyl 3
View attachment 2973522

Cyl 4
View attachment 2973523

Cyl 5
View attachment 2973525

Cyl 6
View attachment 2973531

Spark plugs
View attachment 2973532

 

[middlecalf]

The shape of a lot of those marks points to valve/cylinder impact. But being non-interference engines this can only happen if something lets loose. There is a possibility that a builder of the motor used wrong valves with too long of stems, or the lifter/rods were too long. One guess is from the racing world, where 7500 RPMs has dislodged all or nearly all the valve keepers and the result is quite ugly. So maybe some PO of this motor pushed it and the valves let loose. It’s pretty obvious when this happens, so engine was probably shut down before complete catastrophe happened. And it was repaired, because I haven’t done anything wrt to this topic (cold valve adjustment only which was to only one valve iirc and not much) in getting it running.