Wiseco Piston to Wall Clearance
Wiseco Piston to Wall Clearance Checking piston to wall clearance on a my Wiseco 6394F3 pistons. I'm getting the following:
#1 - .0056
#2 - .0055
#3 - .0053
#4 - .0048
#5 - .0053
#6 - .0052
#7 - .0055
#8 - .0054
I'm not sure what the spec is for these (I've read about .004), but I'm wondering if this is too much to run NA. The variation is the other thing that's bothering me. Measuring the bores, I come up with about a .0005 difference from the top to the bottom, except for one bore, where the difference is about .0009. Other than that, the block seems fine. Machine work was done by a shop in Jersey. I'm about tempted to scrap this block and move on to something else.
#1 - .0056
#2 - .0055
#3 - .0053
#4 - .0048
#5 - .0053
#6 - .0052
#7 - .0055
#8 - .0054
I'm not sure what the spec is for these (I've read about .004), but I'm wondering if this is too much to run NA. The variation is the other thing that's bothering me. Measuring the bores, I come up with about a .0005 difference from the top to the bottom, except for one bore, where the difference is about .0009. Other than that, the block seems fine. Machine work was done by a shop in Jersey. I'm about tempted to scrap this block and move on to something else.
If you aren't measuring with a torque plate attached, it may explain the variation. Wiseco pistons usually have .0035-.004" clearance, so whoa you're seeing is a little loose, but it would run just fine.
Thanks, I guess I needed a sanity check because I AM NOT wanting to invest in another set of pistons lol.
Rather than scrapping the block you could look at piston coatings to make up a little distance.
Here is one I looked up, There are several companies that can do it for you. I'm not sure of the cost though.
PC-9™ is commonly used to salvage a motor that has excessive piston to wall clearance. Vintage motors and other applications with hard to find pistons can have up to .004” of PC-9™ added to the diameter of a piston to tighten piston to wall clearance.
http://swaintech.com/race-coatings/r...piston-skirts/
Here is one I looked up, There are several companies that can do it for you. I'm not sure of the cost though.
PC-9™ is commonly used to salvage a motor that has excessive piston to wall clearance. Vintage motors and other applications with hard to find pistons can have up to .004” of PC-9™ added to the diameter of a piston to tighten piston to wall clearance.
http://swaintech.com/race-coatings/r...piston-skirts/
Rather than scrapping the block you could look at piston coatings to make up a little distance.
Here is one I looked up, There are several companies that can do it for you. I'm not sure of the cost though.
PC-9™ is commonly used to salvage a motor that has excessive piston to wall clearance. Vintage motors and other applications with hard to find pistons can have up to .004” of PC-9™ added to the diameter of a piston to tighten piston to wall clearance.
http://swaintech.com/race-coatings/r...piston-skirts/
Here is one I looked up, There are several companies that can do it for you. I'm not sure of the cost though.
PC-9™ is commonly used to salvage a motor that has excessive piston to wall clearance. Vintage motors and other applications with hard to find pistons can have up to .004” of PC-9™ added to the diameter of a piston to tighten piston to wall clearance.
http://swaintech.com/race-coatings/r...piston-skirts/
Another option is to remove the pistons from the rods, tape off the ring lands, and have a local shop media blast the skirts. Similar to old school knurling this will reduce the clearance by .0018"-.0022" depending on the sharpness of the media used.
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Best simple explanation I can give you is to take a piece of flat stock metal and wack a starter punch with a hammer. Like as if you were trying to create a starting point to center a drill bit for a hole.
Now when you run your finger over that spot you feel the ridges from the metal deformation. media blasting does this thousands of times to the soft surface of a piston skirt which by puffing the surface up, this in turn reduces the wall clearance.
Now when you run your finger over that spot you feel the ridges from the metal deformation. media blasting does this thousands of times to the soft surface of a piston skirt which by puffing the surface up, this in turn reduces the wall clearance.
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Joined: Jun 2011
Posts: 1,343
Likes: 8
From: Katy, TX
those clearances and variations look great, I'd run it.
Which parts of the bore are you measuring? do you have a torque plate or head bolted on for measuring? Even if the block was finish honed with a torque plate, when you bolt the head on the bores will not be round anymore.
Which parts of the bore are you measuring? do you have a torque plate or head bolted on for measuring? Even if the block was finish honed with a torque plate, when you bolt the head on the bores will not be round anymore.
For the two of you that said those clearances are fine, so you're saying .005+ clearances on forged pistons will not in anyway make considerable noise at cold startup and/or excessively wearout the rings?
those clearances and variations look great, I'd run it.
Which parts of the bore are you measuring? do you have a torque plate or head bolted on for measuring? Even if the block was finish honed with a torque plate, when you bolt the head on the bores will not be round anymore.
Which parts of the bore are you measuring? do you have a torque plate or head bolted on for measuring? Even if the block was finish honed with a torque plate, when you bolt the head on the bores will not be round anymore.
I don't have a head bolted on for measuring. Btw, this is an iron block. I know these don't expand nearly as much as the Al blocks.
Last edited by GA95DCMSS; Jan 18, 2015 at 01:53 PM.
I highly doubt it will wear out the rings, but it may make noise at cold start up and then again, it may not. I've seen stroker engines with almost that much clearance not really make much more noise than the valvetrain.
TECH Fanatic
Joined: Jun 2011
Posts: 1,343
Likes: 8
From: Katy, TX
Did you measure at 12:00 and 6:00, or 3:00 and 9:00, or both? Also, do you have the long head bolts or the short head bolts?
TECH Fanatic
Joined: Jun 2011
Posts: 1,343
Likes: 8
From: Katy, TX
yes. My 12k mile stroker motor has loose ptw clearances with Wiseco 2618 pistons and zero noise and great compression.
I have long head bolts I think (2004+ block).
TECH Fanatic
Joined: Jun 2011
Posts: 1,343
Likes: 8
From: Katy, TX
2004+ would be the short head bolts. My theory is that the short head bolts are better because they limit bore distortion when the head is bolted on. I have not tested this theory yet, but I'm getting there.
12-6
#1 - .005625
#2 - .005125
#3 - .005100
#4 - .004675
#5 - .005425
#6 - .005125
#7 - .005800
#8 - .005300
3-9
#1 - .004550
#2 - .004625
#3 - .004975
#4 - .004875
#5 - .004875
#6 - .005175
#7 - .005375
#8 - .004625
Last edited by GA95DCMSS; Jan 19, 2015 at 01:17 PM.
4032 alloy should be around .0025"-.003"
2618 alloy should be around .0045"-.005"
Will it run ??? YES
Is it right ??? That's your judgement call !!!
Plenty of folks would beat that ****** and spray the **** out of it; others might want it factory quiet with no oil consumption issues.
Keep in mind that as the rings seat/wear in, those numbers will increase.
2618 alloy should be around .0045"-.005"
Will it run ??? YES
Is it right ??? That's your judgement call !!!
Plenty of folks would beat that ****** and spray the **** out of it; others might want it factory quiet with no oil consumption issues.
Keep in mind that as the rings seat/wear in, those numbers will increase.