Cylinder bore wear limit

[groove]

Hi All,
just yanked my engine for what I thought was a cracked piston. Turns out piston is OK but rings are missing pieces...
Anyhow there is almost damage to cylinder walls, and even some crosshatching visible on most. Wondering if I may be able to hone and put new standard bore RCD pistons in but would like to measure the bore first to see where its at. Cant seem to find fords acceptable wear limits for standard size pistons.
Thoughts and comments are welcome!

 

[webb06]

You need to check the "roundness" of the bore. I have zero specs for you but I think in the American hogger build there he had specs when his was done. Hopefully you can just go with a hone job and be good.

 

[groove]

Yes exactly. Thanks for the info, I will check out the build a see whats in there.
It would be great to just hone, but the machine shop here is only 200 bucks to bore, although at that point I will check the crank and replace cam bearings...which I should probably do anyhow.
Any problem running new lifters on the existing cam? Im thinking replacing the lifters is cheap insurance, although they all look good.

 

[webb06]

I would think you could have the cam polished just like you can a crank. Either way I would put in all new bearings and lifters.

 

[White_monster]

Specs as follows
Cylinder bore diameter 3.866-3.867"
Cylinder bore maximum taper 0.003"
Cylinder bore maximum out of round 0.002"
Piston diameter standard size 3.863-3.864"
Piston to cylinder bore clearance 0.002-0.004"

Hope that helps. Info right from the service manual.

 

[drunk on diesel]

allowable taper is 3x the allowable diameter variance?

 

[White_monster]

Allowable taper is max 0.003".

 

[2wd-fire]

Yes exactly. Thanks for the info, I will check out the build a see whats in there.

It would be great to just hone, but the machine shop here is only 200 bucks to bore, although at that point I will check the crank and replace cam bearings...which I should probably do anyhow.

Any problem running new lifters on the existing cam? Im thinking replacing the lifters is cheap insurance, although they all look good.

We put new lifters in all 6.0s over 100k getting hgs. And I will in my 6.4 too for less than $200 I wouldn't see why anyone would not.


Sent from my iPhone using Tapatalk

 

[drunk on diesel]

Allowable taper is max 0.003".

cylinder bore diameter = 3.866-3.867"

an allowable variance of 0.001"

Allowable taper = 0.003"

.001X = .003

solve for X

 

[White_monster]

Yes. Let's get all mathematical in here.

 

[78f100]

Yes. Let's get all mathematical in here.

LOL

 

[drunk on diesel]

Just saying it sounds like allowable taper is .001

 

[White_monster]

No, allowable taper is maximum 0.003" no matter what the bore diameter is. I'd have to double check the book but I believe if the bore to piston clearance is greater than 0.0035"-0.004" you need to bore the cylinder same as if the cylinder taper is greater than 0.003".

This isn't a mathematical equation, it's engine building basics.

 

[forcefed6.4ford]

Forest! Shush!

 

[groove]

Thanks guys, will see what the machine shop comes back with this week.

Will be replacing lifters and rockers as well. Cam should be fine I imagine.

I was anticipating a cracked piston, but when I tore it down found that #2 had broken top and middle rings, #5 broken top ring and #8 broken top ring. Surprised it ran as good as it did...but now I know why it was smoking so bad!