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Discussion Starter · #1 ·
Still have a very nice guy at Ford racing trying to locate a new piston for the mid-90's 5 liter for us. He's been very patient and helpful but he's now asking for the "Magic Number" that is supposedly on top of the original #8 piston, or on top of the head. He says those engines were/are assembled using pistons labeled/rated as #1, #2 or #3's. I can't find a single mark anywhere. Any ideas gents? He asked if I've honed out the cylinder yet (no) and then suggested going with a #3 piston (largest of the three), as he's assuming I'll be taking out a lot of meat. So at the moment I'm kinda in neutral. Not sure wheter to hone first and measure second, and then give him the new size? Or just gamble and go with a new piston marked number 2? Hmmmmmm, auto repairs..........

Thanx
 

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Convicted Drunk Dialer
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Does it look like it needs to be honed? I think I remember in your other thread you saying it had ~1000 miles. If you still see crosshatch and there's no other damage theres no real need to hone it.
 

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Satyr of the Midwest
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Can you get some specifications for these pistons from them, instead of just #1, 2, or 3? Just assuming what size you need is going to lead to disaster. That cylinder needs to be finished FIRST, then measured with a telescoping bore gauge and micrometer or dial caliper. Only then will you know what size the piston needs to be.

You're really being a good sport about repairing their assembly F-up (IMHO).
 

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Discussion Starter · #4 ·
1). For Chebbie-----yeah, it's gonna need some light honing because the slapping piston skirt created thin verticle grooving on about 50 percent of the bore, but on the other 50 percent the c/hatching is still there. Also upon more reflection the engine has less than 150 miles on her since my son over-heated it and caused the damage.

2). For Sig-----I was kinda leaning in that direction as well...hone, c/hatch, measure and then order. I sent pics and every number on every part to Steve at Ford but he says he still can't decipher (using old Ford records?) exactly which number piston was installed originally.

Nothing's ever easy is it? I think it's time to pull out the power tools..........
 

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my bko ate my money
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ya do what sig said....finish the cylinder, then measure, then order, its not easy but not hard just time consuming and delicat, make sure you put the right finish on the cylinder so the rings seat properly
 

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I'd never heard of them having different sizes of pistons...I'm not sure if I believe that. With modern manufacturing tolerances the block should have all bores finished out to the same size and then pistons dropped in that are all the same size. Matching three different sizes of pistons to each cylinder would be a lot of extra time and effort on the assembly line. I could be wrong...but that seems really fishy. I've worked as a parts guy at a dealer...they don't always know what they are talking about...including me at times! :doh0715: I'd call a different dealer and see if they say the same thing or not.

As far as honing...if the bore ends up a little on the loose side you might look into having a replacement piston coated. Been a long time since I read about it but you can get ceramic/wear resistant finishes that coat the piston and can add a little to the diameter. Usually the coating is very thin but maybe it can be applied thicker...just something to check out.

Derek
 

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Discussion Starter · #7 ·
Thanx for that Derek. Something does sound strange...and here's why. I honed the bore today and it measures pretty close to 3.86 inches at the top right now. (Haven't used the Flex Hone yet nor run a real micrometer in the bor at different locations. Mostly because I can't find anyone who rents them...not even AutoZone.) Then I measured the piston across the top on an undamaged area and it reads out at 3.80 inches. Now on page 2D-5 in Mr. Haynes they state that the piston diameter on the 302's, 1991 and up is 4.0001---->4.007. Which is a pretty big discrepancy. The only thing I can think of is that when the guy at Ford told me that this engine was a late '90's 5.0 that were surplus engines that went into the Explorers, then maybe that could explain the size difference. I'll have to run this info past him tomorrow and see what kind of explaination I get from him.

On another note I used the tripod style stone hone today with my Makita cordless 9.6 volt ninety degree drill motor. Worked like a champ. I'll toss some more pics up tomorrow if/when I can get the FlexHone tool and a proper mic.....


EDIT---Forgot to mention that in the Haynes the matching cylinder bore is supposed to be 4.0004-----> 4.0052 inches. My public school math computes the gap/spacing between piston and cylinder at somewhere around .0002 to .0045. Am I close?....
 

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Satyr of the Midwest
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Something is seriously wrong with your measuring instrument then. Both the 5.0L and 5.8L engines share a nominal bore diameter of 4.00 inches. 3.80 inches is WAY too small. I mean really, a 0.200-inch discrepancy?

And yes, there are select-fit pistons. Check out the Haynes manual, and it lists them (or at least mine does lol).
 

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Discussion Starter · #9 ·
Anyone got a clue on how to get a hold of an accurate dial bore indicator and a FlexHone for cheap/free? The FlexHones are almost $80.00 and the least expensive dial indicator is an import cheapo at $120.00------------and they go up to $500 plus. I found one at a pawn shop but they guy wanted $250.00 for it. Called all the tool rental shops and nada. Plus I even tried to bribe a couple of local mechanics but to no avail. Hate to spend 2--3 bills on two toys that I'll only use for 5 minutes.

Operators are standing by..........
 

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Discussion Starter · #11 ·
harborfreight has one for $100 cheapest i found
The dial type? Cuz I was right there today (when the quake hit in fact) and all they had were the slide-rule style micrometer goodies. The three guys that have worked there the longest said they had never seen one in their store.

This is what I got;





And this is what I need;





Any So Cali mechanics here wanna make some easy moola?........
 

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my bko ate my money
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Discussion Starter · #13 ·
no this is what i found when i went there

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=94873

no luck on your hone though just found that bore gauge



Gawd, I wonder just how accurate that Centech gauge would be. Cuz right now I'm looking at my feeler gauge and the .0018 blade (which is the piston to bore gap average) and to quote my first g/friend 'There ain't a whole lotta meat there'. Meaning if it's off just a hair then I'll probably be playing piston tag with Ford 'til I get the right sized one. Hmmmm.

Btw Gents, when these parameters get down to so precise as to require numbers like three ten-thousands of an inch and such, wtf do they use to measure with? It certaintly can't be 250 dollar goody like these?.....
 

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my bko ate my money
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Electronic readout
Displays Metric or SAE units
Gauge accuracy: 0.0002'' /0.005 mm

Includes anvil sizes 1.4", 1.6",1.8",2.0",2.2" 2.4", 2.6",2.8", 3.0", 3.2", 3.4", 3.6", 3.8"
 

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Satyr of the Midwest
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my bko ate my money
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