Mis labeled pistons?

[standup303]

Just finished disassembling my 440. Tops of pistons are all stamped .030 I pulled the measurements below. Are the pistons mis labeled?

Cylinder Piston
#1 4.336” 4.326”
#2 4.329” N/a still installed
#3 4.336” 4.322”
#4 4.333” 4.321”
#5 4.335” 4.321”
#6 4.339” 4.324”
#7 4.335” 4.324”
#8 4.335” 4.322”

 

[IQ52]

Where are you measuring the pistons?

 

[33IMP]

Well, nothing there, pistons or bores, are .030 over. And they aren't .030 over 426 wedge either.
Ten to fourteen thou piston to wall, you have a MESS there.

 

[RustyRatRod]

The BORE is what is .030 over size. The piston has to be smaller for clearance.

 

[standup303]

Where are you measuring the pistons?

Those were at the top before the first ring. I just measured mid piston and they were all 4.345-4.348.

I can only measure about 1/2” down inside the cylinder with the caliper I have and that’s where those measurements are from.

 

[33IMP]

The BORE is what is .030 over size. The piston has to be smaller for clearance.

Yep. .030 over on a 440 should be 4.350, pistons same minus clearance, say 4.344-4.348

 

[RustyRatRod]

Those were at the top before the first ring. I just measured mid piston and they were all 4.345-4.348.

I can only measure about 1/2” down inside the cylinder with the caliper I have and that’s where those measurements are from.

You measure at the skirt.

 

[RustyRatRod]

Be

In his particular case with standard size pistons, 4.320 and the bore 4.350. no !

cause he was measuring at the wrong spot. lol

 

[MOPARMAGA]

Be

cause he was measuring at the wrong spot. lol

Yeah, I actually saw farther in the thread and erased that post, I wasn't fast enough lol

 

[MOPARMAGA]

@standup303 don't cut that beak off eventually you'll want it back

 

[standup303]

The pistons are pretty close to 4.350. Thinking this caliper doesn’t have long enough arms to get down in the bore for a better measurement.

 

[MOPARMAGA]

The pistons are pretty close to 4.350. Thinking this caliper doesn’t have long enough arms to get down in the bore for a better measurement.

Calipers are good for quick close measurements.

 

[standup303]

@standup303 don't cut that beak off eventually you'll want it back

Lol your probably right

 

[MOPARMAGA]

Lol your probably right

Yeah, I used to think they were ugly when I was a kid, now I'd love to own one

 

[fishmens67]

Do you have the new.030 rings? old rings?
You could stick them in the bore in various spots starting from an inch down and measure the end gaps.
It would give you some kind of idea what your working with.

 

[Bewy]

Caliper is not accurate enough for this, especially digital or dial calipers. A micrometer is needed & I would doubt once measured properly that there would be 0.003" difference [ assuming no wear.