Queston for US1, JSRE or Greg Moss. How loose is too loose??

[DUCKY]

I'm puttin the 225 block together so I can get back on the water, and all of the bores are within +.005" of standard except one. I got one that is 3.397". I have a piston that will net .015" skirt to wall clearance. If I put in this piston, am I asking for this thing to come apart, or will it live? My other option is a Wiseco that will net .003" clearance (It's 3.394" Dia), but being a forged piston won't this expand and scuff? Will this thing live with either of the aforementioned pistons, or do I need to break down and buy a .015" over. If this is the case, does any of you guys have a used one laying around? Thanks for your help, Scott:confused:

[us1]

Neither one of the pistons will work at all. The Wiseco is a super expander and scuffer. You will need a minimum .007 to get the Wiseco to work. The .015 piston will run a short time then fold up the skirt and wedge in the bore sideways. You better get the right one. The bore in question is .020 over. Is that an out of round measurement or has it been sleeved and bored .020 over?

[DUCKY]

That's kind of what I figured, but I had to ask! Step 2, anyone got a .015" over stocker piston laying around??
It was sleeved and bored, just to answer your question John. Thanks for your input. :D

[us1]

A .015 over wont fix it. your are .022 over. You need a .020, looks like it was bored for a Wiseco.

[DUCKY]

T-rex said he has some .020" over seizeco's Will that fly?:confused:

[Greg Moss]

Get a hold of rick and see what he can do for you on price. If Rex has it it more than likely is as old as he is. If you run a Wiseco send it to John and have him top pin it.

[Arizona Hotboater]

Hey Duckman,
how about this idea.

BUY A NEW PISTON! :D

[DUCKY]

Do you see a problem with continuing to hone the cylinder to gain the proper clearance? I'm only .008" away!:confused:

[us1]

You are perfect for a Wiseco now, they come .020 over. Do not use a hone to get .008 it will taper and egg shape the cylinder. You need a boring bar to go that big. What is the out of round measurement on the 3.397 cylinder.

[DUCKY]

I got a hone with really long stones on it, (I figured the worst case scenario was needing a sleeve) It measures 3.402 +or- .001 all the way around, and that smallish .030" over piston will now fit a .010" feeler in between the wall and skirt. A .012" feeler will not fit. Is this kosher?:eek:

[us1]

You can't measure the piston clearance with a feeler gauge. You need an inside mic and an outside mic. You need 3.406 for a .030 over. I have been doing this a long time and have never seen a cylinder that was straight after a .004 hone.

[DUCKY]

I'll be praying this thing stays together! I could use some help!!:cool:

[Arizona Hotboater]

I was at Duckys place today and saw the block. He did a really good job of opening up the bore to fit that .030 over size piston. I agree on the bore vs. hone but it looks as though he may have gotten it right. We will see. Lets hope I dont have to tow him in. :D
AZH

[us1]

It will seize in 5 minutes with the bore that tight. You cant see taper and out of round with the naked eye, you need mics.

[Greg Moss]

wonder how good a deal he has on ROPE? Sounds like there may be a market for some here

[us1]

Originally posted by Greg Moss
wonder how good a deal he has on ROPE? Sounds like there may be a market for some here

Now that's funny. I have started to realize that he is pulling my leg on this just to see how far I'll go.

[Greg Moss]

I think he may be serious some guy's will try things to save some money and in the end have to spend 10times what they were tring to save.

[B.Leonard]

Good point on using a hone to get extra clearance.

Since we're on the topic... I have the mics (inside and out) but where is the best place to measure the piston? Those things are not round by any means.

Also I wonder where the manufacturer expects you to measure them? They don't say. They tell you how much clearance but not where to measure it from.

-BL

[Greg Moss]

depends on the piston some want you to measure 90* to the wrist pin Mercury you measure the skirt with the wrist pin and 90* to it

[us1]

Yes Greg is correct, on Mercury measure the skirt 90 degrees from the wrist pin. That's why you could never use a feeler gauge to get an accurate measurement. Not to mention calculating in the bore taper and out of round.

[B.Leonard]

That's where I always measured them on 4 stroke motors, but I noticed 2 cycle pistons seem to have even more varience.

I took some old pistons and noted where they scuffed and measured from there. On the crossflows I've built I think it was about 45* from the pin and slightly above the centerline of the pin.

The manufacturer should tell you this :rolleyes:

-BL

[us1]

They want you buy a new motor not fix the old one. I.E. it must have taken years to perfect a ring locator pin that falls out right at 100 hours.:D

[B.Leonard]

I saw those pics of the work you did for Danny.

Is that what JSRE does?

-BL

[us1]

He does it by staking the original pins.

[dan agnew]

dont make a mistake of this magnatude. if that pistons grabs u will be doing more than minor repairs. i have seen fresh engines sieze at 2500 and pull the rod apart. next rotation you can inspect interior of engine from outside.
listen to john, he is trying to help ya.

Danny

[Arizona Hotboater]

Well, you guys think it will fail on the flush kit? Duckman intends to run it a while that way before we hit the lake. I have plenty of rope, just in case. Ducky usually has luck on his side. I am keeping my fingers crossed for him.

AZH

[KIRCHNER]

wonder how good a deal he has on ROPE? Sounds like there may be a market for some here oh, thats cold!