Give us your thoughts on these pistons

These pistons are from (342g) Harold Websters engine. During cleanup I found the skirts in this condition. 6 of the piston skirts were in this condition on the outside.Some were high on the skirt and some were on the lower part. They look like weird rough scuffs on the outside but on the inside they are actually cracked. At first I thought it may have been due too to much side clearance,but after I mic'ed the skirts they were w/in tolerance.anywhere from .006 to .009.The engine had approximately 3 to 400 passes on it after a fresh bore on the block. The block also had some ware lower in the bore. It was on alcohol. Any one seen this before or know what might have caused it?


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what brand and type piston?

Dome Venolia Forged .Standard valve layout.

Being that there is a significant shiny ring just below the oil ring groove, it would appear that the RUNNUNG clearance was at some time or another to tight. That can be from a number of situations.
1. running piston temperature got way to high at sometime
2, water temperature to cold for the amount of piston heat
3. not enough bore clearance to begin with.

How used are they?

Just a wild guess. 8 or 900 passes. I did'nt assemble the engine the last time but I did on other freshenings and clearances were good. The only other thing this time around different was it was changed over to Alky.

Pitts IMO are the Alky atacking the Aluminum. May need to work on the maintence before storage.

May even be from sitting over the winter.

what do the cyl walls look like?

Rick,

Those are Venolia? Is that a 1/16, 1/16, 3/16ths ring package? Kinda' looks like an old 5/64" deal to me. Anyway, alcohol attracks water/moisture and it sure looks like some corrosion was taking place on the skirts and or cylinder walls. If it was mine, I'd bore it and put new pistons in it, then switch back to gasoline.

Charlie

Is the block sleeved?

I had a sleeve and a piston with similar symptoms, just at the top instead of the bottom. The sleeve was moving round and caused a bunch of fretting that looked similar to what you've got on your pistons.

Have you checked to see if the cylinders out of round?

The bores actually looked good.I wiped them out and took a look before I took it to the machine shop to be honed.Machinist said the bores were wore more than normal for just 3 to 400 passes. It was a fresh bore by the same machine shop before the last assembly. While I was disassembling the engine,I took a top and second ring off the piston and put it back in the bore to see how much the rings had wore,and to my surprise the had .0035 gap in the rings. I'm maybe thinking that the alky was washing out the cylinders w/that much ring gap.

it looks like a realy fat tune up to me and that crack dont realy look like a crack. but it is a pic i'm looken at,you've got the piston.lol.i've saw a lot of bbc pistons out of pull trucks look that way.they dont get much heat in them before they see abuse.

Yea,i'm planning on running alky this season. I think a heater and a leanout will be a must.And a really good maintenance program.

I see no reason to put it back on gas, but then again you cant treat it like it is on gas.........and even gas race engines need a little TLC between races.

FWIW I've been into a lot of engines run on meth and the cyl walls will usually look a lot worse than the skirts.

Bore it, toss a new set in, get a good storage regiment between races and go on. Also the block heaters help a bunch, if everything is already up to temp its gonna seal up a lot better from the git go, oil heater is another very good idea.

Hell 800 passes is a bunch.

I'm thinking that there is probably alot of things that might have contributed to all this. The pistons had some age,alot of use,maybe some not enough HEAT,and some cylinder washing. I agree w/slapping a nice set of quality slugs back in since the cylinders are ready and he will be good.

As most others have replied, the storage between race events IMO have created most of the damage you see. Cylinders have rust, the piston is moved and the rust does two things, scratch the pistons and walls as well takes up valuable piston to wall clearance and may have contributed to the skirt breakage. The ring area looks a if had it's share of corrosion issues as well. Crazy things can happen!

Remember the presentation Jon Kaase gave of header rust being pulled into an engine and causing ring damage?

When your drunk on alcohol, the consequences can be alarming!

Just my worthless $0.02,
Dave.

top ring gave up .

I always get my engine up to around 190-200 with the lean out before shutting it down after a race to get the pistons warm enough to evaporate anything that could seep into the cylinders after shut down. A carb can seep alcohol into the combustion chambers in or on the trailer on the ride home.

I have ran alcohol for 15 plus years and have not had an issue like this , not saying it couldn't happen because it could there are just certain things you do when running methanol. I would not let the fear of corrosion change my mind on running methanol there are simply way to many advantages to running methanol in a bracket racing application that is why methanol is the dominate fuel at big money and weekly bracket races.

its hard to tell from pics,but this could be caused from 2 diff conditions,and have 2 different problems


ive seen this from to much rock of the piston, and detnation,then breakdown of oil on top of the above

When I removed the rings from the pistons, I did find quite abit of rust in the ring lands. Whether it be from rust inside the headers,or rust in the cylinders. But,the cylinders were free of rust or pits on disasembly. Harold and I spoke on the phone today and he said that when he first put it on Methanol that he felt he had washed the cylinders a few times.

bbf-falcon wrote:When I removed the rings from the pistons, I did find quite abit of rust in the ring lands. Whether it be from rust inside the headers,or rust in the cylinders. But,the cylinders were free of rust or pits on disasembly. Harold and I spoke on the phone today and he said that when he first put it on Methanol that he felt he had washed the cylinders a few times.

washing the cly will give us that wear,but not cause cracks, this thing had to be ratteling ? are the ring lands still tight? were the gaps all lined up?

reading back, maybe the cracks were fourming in the other engine they were from/ honed too big? but like was said too tight would make the scuffs with a lot of heat. Its nice to always know what happened ,and we'll prob never know in this case as they are ash trays now


my $$ is on the fact they were cracking in ( or weakened) the first engine they were in,and not seen when installed in this one,once in this one after being washed bad,ratteled a little and cracks came to the surface to be really seen. either or this is whay we take them apart, you did good by catching it now

From the looks of the slugs,some of this damage is high on one side of the skirt and lower on the other.Which makes me think they were rocking some.
Like Rich said,we will probably never know 100% but I think we have some good ideas. Thx for all the replies.

BOSS 429 wrote:

bbf-falcon wrote:When I removed the rings from the pistons, I did find quite abit of rust in the ring lands. Whether it be from rust inside the headers,or rust in the cylinders. But,the cylinders were free of rust or pits on disasembly. Harold and I spoke on the phone today and he said that when he first put it on Methanol that he felt he had washed the cylinders a few times.

washing the cly will give us that wear,but not cause cracks, this thing had to be ratteling ? are the ring lands still tight? were the gaps all lined up?

look at the back wall of the oil ring . I'd say the ring lands were glass beaded . not a good idea to do

DanH wrote:

BOSS 429 wrote:

bbf-falcon wrote:When I removed the rings from the pistons, I did find quite abit of rust in the ring lands. Whether it be from rust inside the headers,or rust in the cylinders. But,the cylinders were free of rust or pits on disasembly. Harold and I spoke on the phone today and he said that when he first put it on Methanol that he felt he had washed the cylinders a few times.

washing the cly will give us that wear,but not cause cracks, this thing had to be ratteling ? are the ring lands still tight? were the gaps all lined up?

look at the back wall of the oil ring . I'd say the ring lands were glass beaded . not a good idea to do

Never beaded. Just brake clean and air.