Wiseco oversize piston fitment issue

[littleape]

OK I'm scratching my head at this and can't figure out whats wrong, kinda feel dumb posting this but I'm stuck.


I'm working on a '90 Evinrude 150, I oversized 5 bores to 010 over and one to 064 over.

I did the 010 over cylinders to 3.510 and the 064 to 3.564

The 010 over are using WSM pistons and the 064 a Wiseco, all brand new.

The 010 over pistons fit nicely, slide in and seem to have good amount of side to side movement. The 064 Wiseco will not fit, anything past 1/8" requires pressure. These test fitments were done without rings.


I measured things a million times, I have a bore gauge, micrometer and digital calipers. Measured the bore in every spot I could think of, from the very edge at the top to the very bottom in a bunch of position up and down and rotating. According to my bore gauge in no spot does it go under 5.564 and if anything it's slightly larger by a thou. The piston looks to measure 3.558 - 3.559


What could I be missing here?

 

[racerone]

Are you measuring at the skirt of the piston ?------Is the piston round ?-------What happens if you put the piston in the cylinder ring end first ?----What does that test tell you ?----Put some mechanics blue in the cylinder to see where the interference is !!

 

[littleape]

Are you measuring at the skirt of the piston ?------Is the piston round ?-------What happens if you put the piston in the cylinder ring end first ?----What does that test tell you ?----Put some mechanics blue in the cylinder to see where the interference is !!

Measuring at about 1/2 from bottom of skirt.

Going crown in first it goes in up to the pin before pressure.

I do see some residue from the coating rubbing off on the cylinder walls but using my bore gauge to measure at those points comes up dead on perfect 5.564

 

[Scott Danforth]

what does the bore gauge tell you about the piston taper and roundness?. measure bottom, mid, and top of bore. then rotate gauge 90 degrees and repeat


if youre measuring 5.564" on a 3.364' bore...... you have a different problem

 

[littleape]

what does the bore gauge tell you about the piston taper and roundness?. measure bottom, mid, and top of bore. then rotate gauge 90 degrees and repeat


if youre measuring 5.564" on a 3.364' bore...... you have a different problem

Ya that was a typo, meant to say 3.564 not 5.564


Taper and roundness are within 0.0005 measured in 6 spots (bottom of cylinder, between ports and about 3/4" from top. It's also the same just measuring all kinds of random spots throughout the cylinder. This is so weird.

 

[racerone]

----I say ----1-800-wisecomanhelp me------They may well be aware of an issue with a batch of pistons.-------Explain politely and I am sure they will assist you.

 

[littleape]

Hmm I think this cylinder is whacked, I put a ring into it and its overlapping. There are spots all around with gaps between the ring and the walls of the cylinder I think it was measuring fine because the low spots have opposing high spot.

Anyone know where I can get a sleeve for one of these?

 

[Tim Frank]

Ya that was a typo, meant to say 3.564 not 5.564

You did it repeatedly....

Taper and roundness are within 0.0005 measured in 6 spots (bottom of cylinder, between ports and about 3/4" from top. It's also the same just measuring all kinds of random spots throughout the cylinder. This is so weird.

Did you do the boring yourself? Do you know what tool was used.
Try a straight edge on the bore.....i.e. see if there was any drift.

 

[littleape]

Did you do the boring yourself? Do you know what tool was used.

Yeah I did it myself using Lisle LI15000, not sure what went wrong with this cylinder but the other ones that are 010 over all fit a ring correctly with the entire circumference making contact.

 

[Tim Frank]

I have a full machine shop in my basement but am strictly an amateur.
That said, and take it with a grain of salt because "I am an amateur" , my basic understanding would tell me that you were trying to rebore with a hone....not the correct tool......and you simply do not get a properly aligned result reliably when taking off as much as you tried to remove. I would bet that the centre axis of your new bore is not a straight line.
Imagine a series of discs stacked up. The tower can be "bent"....each one is the correct diameter, but collectively you no longer have a true cylinder. A straight edge should prove that

The 0.010" rebores are OK (presumably) because there was far less material removed.

We have some experts in here; if one of them checks in they might have a better opinion on what went amiss.

 

[racerone]

In an earlier thread it was clearly stated that it was MACHINED to this size.----Good camera work so far but perhaps post a picture of the machine and boring bar that was used.----And the honing tools.

 

[Tim Frank]

The Lisle 1500 is a honing tool used with a hand held drill for cleaning and patterning a cylinder....usually after a rebore.
What little I know of machining best-practice says that you do not rebore a cylinder (a highly-precise operation) using a hand-held clean-up tool.

But I could be wrong.

 

[Tim Frank]

In an earlier thread it was clearly stated that it was MACHINED to this size.----Good camera work so far but perhaps post a picture of the machine and boring bar that was used.----And the honing tools.

No...OP said "I oversized 5 bores to 010 over and one to 064 over."

Geometrically if his bore gauges are accurate and he knows how to use them, the only cause of the problem that he describes is a lack of axial straightness; i.e. a wobbly tower of blocks.

 

[littleape]

Yes it was a lot to remove with that tool. I guess too much. No going back now.

Now I need to grab a sleeve and have a shop replace it. Any better than the price here ?: https://shop.tsmperformance.net/Cyl...p-1971-98-3500-Bore-1000SA.htm?productId=1248

 

[racerone]

Nope----In an earlier THREAD and not this one he stated it was machined.----I also do my own boring and honing.-----Friend has a full machine shop where I pay a small fee to work on his equipment.

 

[racerone]

Find another block !---As per post #2 in the other thread.---Not that hard to find in my opinion !!-----But you now know that experience is a great teacher.

 

[Tim Frank]

Nope----In an earlier THREAD and not this one he stated it was machined.----I also do my own boring and honing.-----Friend has a full machine shop where I pay a small fee to work on his equipment.

Sorry, did not see the other thread.

 

[Bt Doctur]

even to sleeve a bore the bore has to be perfectly round to begin with

 

[littleape]

even to sleeve a bore the bore has to be perfectly round to begin with

I think a shop would cut it out and then press in a new sleeve.

I'm not in US so finding a replacement block isn't simple, the only one on eBay i see is $550 and would probably require work ontop of that. Shipping that chunk would require a small fortune.

 

[GA_Boater]

Why would you buy an unported sleeve?

Sleeves need to be machined after installation because they end out of round. Are you having the shop do the machining?

If I was doing this, I would buy a ported sleeve, have a shop install and bore, as well as have them check the other bores.