Oversize pistons

[seapadrik]

So I was just talking with the machine shop and they thought maybe they could just hone the cylinders but now he is thinking they should be overbored.

He says the current pistons are already .040 oversized and I would need a .050 size piston.

I am not seeing any pistons that oversized on the Moyer catalog, should I be nervous ? I s there such a thing available ?

Thanks

[hanleyclifford]

My understanding is that pistons for the A4 come in .010", .020" and .030" oversize. Many believe that only the .020" is acceptable. If your pistons are .040" oversized, they must be some other brand and in my view the walls must be very thin. A better plan is to have the cylinders resleeved to standard.

[seapadrik]

Thanks for the response. It turns out I got lucky in that the shop got it wrong. Something about a typo. Anyways I had them call moyermarine and get the specs.

At present I will only need to get the .010 oversize pistons.

[hanleyclifford]

I was hoping for something like that. You should be good at .010" over. I am at .020" over now but I will not go to .030". Next move will be to resleeve to standard. I have already done this on another engine with excellent results. All the best, Hanley

[JarrettF]

Hanley, and all,

I am mid-rebuild. My cylinders are already .020. I wanted to resleeve, but the machine shop I have doesn't have a supplier who has sleeves that will fit. And I don't know where to get .030 pistons and rings.

What to do? Any ideas of suppliers or options I can now take?

Thanks!

[Ball Racing]

People are scared to bore a block past .020 over, but are willing to bore it out to sleeve it to get it back to standard bore.

Well for lots of sleeves depending on what you use you will need to go to around .100 over bore to contain the sleeve. That would only make the new cylinder wall .050 thick. You may use a even bigger sleeve.

Okay, you need a good amount of cylinder wall left to hold the new sleeve.
If .020 and .030 is cutting into the water passages then sleeving the block will be just as bad, or worse
as the new sleeve without good support can move around and go out of round and lose ring seal.

With both sides of the cylinder having water go past it, it's not much strength to hold it rigid when you bore it large.
You may cut through alot of the original wall when sleeving, then it's weaker.
Putting a sleeve in does not make the cylinder area stronger, it requires a press fit to keep it in place, and when you inlarge the bore for a sleeve, the block can lose it's clamping strength.
I might consider it for one piston, but would not sleeve the whole block..

This may not totally apply to this engine, but for 15 years of building briggs flatheads, this is what I ran into..

[hanleyclifford]

It does seem a little unnerving to bore past a cylinder wall into the water jacket but I have it on good authority that the cylinder, the sleeve, derives it's support from the two landings of the block and does not get much support from adjacent cylinders. If the crankcase end and the head landing are sound all the way around the circumference of the sleeve there is no problem with stability.

[lat 64]

I have seen sleeves put in auto v8s where the factory block had a casting core shift and the original cylinder walls were so thin they got cut through on the first oversize boring(.010"). The repairs were fine.

L. A. sleeve Co. was always the place to go in the ol' days. It's still there, but with a clunky web site.
http://www.lasleeve.com/master.html
I think the a-4 is a standard inch and fraction size, so there should be something to fit it. Somewhere!

Never say "can't":D

Russ
Update:
I vote Jarrettf's avatar pic the best avatar EVER!

[JarrettF]

Russ
Update:
I vote Jarrettf's avatar pic the best avatar EVER!

Thanks Russ, it's from one of those WPA/WW2 posters, Merchant Marine or something. I love the pic and its sentiment. And it kind of looks like me in that average white guy way.

I am considering sleeving all four cylinders. I contacted marinedieseldirect.com and got a price for 30-over pistons and rings that will put my wife into early labor.

How deep/how much can he bore out to make the new sleeve fit? As much as he needs to (because the sleeves will replace all that bored out material)? I can't exactly explain why, but structurally the idea of sleeves and standard pistons & rings makes me feel better than 30-over pistons.

Otherwise my block is in good shape; I have done an acid flush 3x in the past 5 years.

[lat 64]

I just remembered that my boss used to goop-up the new sleeve with some kind of ceramic sealer when installing a sleeve in a bore that had been bored through into water. He said this was just an extra precaution. If you measure a .040" oversize piston, you will see that it is .020" larger on the radius. So you will bore .020" into the block. About the thickness of my big toenail. I know I'm not too worried about oversized pistons:) ....She's my little duece coupe, you don't know what I got.

ta,

[JarrettF]

OK. I give.

I found 30-over pistons, but rings are on a 7-10 week backorder!

So I figure, fine, I wanted to resleeve anyway, but the machine shop can't find sleeves small enough from his suppliers for the A4.

(I left a message with Ken, already.)

Any help?

[JarrettF]

Ne'ermind!

I called LA Sleeve and we're good to go! Thank you, Russ! I dismissed them after seeing only JetSkis on their site, but it looks like they have something that'll work.

mmmm...back to standard!

Thankthankthank you!

[lat 64]

Oooh, Jetskis.
That'l empty the barracks. Around my house they're known as target drones. We're trying to get the State of Alaska to open a season on them. Maybe something with "fair chase" sporting concerns like smooth-bore or black powder only.

I know, I'm bad. Gotta love their technology though. All that power in a hobby horse.

[Administrator]

We have these on our creek at times. Anybody know of a source for piano wire? Anybody got a friend with Special Ops training?

Bill

[JarrettF]

1. For future A4 sleevers, you definitely want to call LA Sleeves. Ask for Dave. And the part # you want is T209.

2. The guy across from us on our creek had a jetski dock built over the Spring. So far so good - I mean, if it has to be there, at least he has been calm and respectful about it. We were mighty worried about it, though.

[lat 64]

Jarrett,
Can you take some photos of the process and document it in a new thread?
This is always coming up in discussion. If it is a good fix, we could flag the thread with keywords to direct searches for other potential sleevers to find.

Just a thought,
Russ

[67c&ccorv]

We have these on our creek at times. Anybody know of a source for piano wire? Anybody got a friend with Special Ops training?

Bill

I'd be happy to see them taken out with a CIWS mounted on a frigate...:D

[sastanley]

Ha...have you guys seen the guy with the rocker launcher on the Hobie Cat? :D

We just call them creek gnats and big mosquitoes around here. I also have a few friends that are power boaters (& own jet skis) and for the most part they know what they are doing.

However, there are always the guys with the jet ski on a trailer that lives in the condo and comes out only on the weekends and jumps big boat wakes all day. :rolleyes:

[JarrettF]

Jarrett,
Can you take some photos of the process and document it in a new thread?
This is always coming up in discussion. If it is a good fix, we could flag the thread with keywords to direct searches for other potential sleevers to find.

Just a thought,
Russ

Definitely.

If it's not a good fix you won't hear from me again because I will have gone berserk and I'll be living out my days making pot holders at some institution somewhere where there are no boats, no water, and no engines.

[roadnsky]

If it's not a good fix you won't hear from me again because I will have gone berserk and I'll be living out my days making pot holders at some institution somewhere where there are no boats, no water, and no engines.

Nah! You'll be back.
Once a sailor, always a sailor... :p

[hanleyclifford]

We have these on our creek at times. Anybody know of a source for piano wire? Anybody got a friend with Special Ops training?

Bill I think this is a more sanitary solution. http://www.balinorintl.com/water_cannon.html