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Smog 440 bore?

jeepthrills01

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Man I seem to consistently find the weird ones.
So my 04/12/1978 440, which "allegedly " came from a low mile motor home...just for giggles I measured the bore (3 different depths, 2 different directions all 8 holes) and i come up with the same exact measurment...which normally would put a huge smile on my face...nothing out of round...all even...no ridge.

But the number....which i double checked with 2 different gauges (one of which was just calibrated for FAA repair station use....has me tearing my hair out.... is 4.317. WTH?

Someone school me please...and no..there are no sleeves in the block.
 
Man I seem to consistently find the weird ones.
So my 04/12/1978 440, which "allegedly " came from a low mile motor home...just for giggles I measured the bore (3 different depths, 2 different directions all 8 holes) and i come up with the same exact measurment...which normally would put a huge smile on my face...nothing out of round...all even...no ridge.

But the number....which i double checked with 2 different gauges (one of which was just calibrated for FAA repair station use....has me tearing my hair out.... is 4.317. WTH?

Someone school me please...and no..there are no sleeves in the block.
Which bore diameter were you expecting? 4.32?
 
Well...yeah
Well, your 440 block would actually be the third 440 I have either seen or heard about with a bore diameter less than 4.32". I actually have a 06/27/1976 date code 440 that had a standard bore diameter of 4.318 no matter which way I measure it.
 
What do the pistons measure? Numbers on the pistons?
 
Nope. 4.340 is standard 400 b

I disregarded his comment...this is no 400

20210406_183922.jpg
 
Well, your 440 block would actually be the third 440 I have either seen or heard about with a bore diameter less than 4.32". I actually have a 06/27/1976 date code 440 that had a standard bore diameter of 4.318 no matter which way I measure it.

Did standard bore pistons fit without a bore job? Was hoping for a home garage redo.
Looks like i may need to bring it in to get.."standard"
 
Did standard bore pistons fit without a bore job? Was hoping for a home garage redo.
Looks like i may need to bring it in to get.."standard"
I had a standard set of Diamond Pistons on the shelf and the piston was super snug in the hole. Just as a test I had to hone the block .004" to make the standard piston fit perfectly.
 
The bore is finished to the piston to get the proper clearance. So your pistons are small. Not that big of a deal. You measure the pistons first. You don’t bore it to 4.32 and then measure the pistons.
Don’t take it in and say bore it to 4.32. Have the bore size fitted to the pistons for proper clearance.

You are very Lucky to have such a good bore with no wear. Don’t pull your hair out, it will come out on its own in the coming years. LOL
 
Blocks and cranks normally have "selective" parts to set the appropriate clearances. They aren't going to send a block or crank back to get re-machined when the size isn't optimal. A lot of engines are stamped by the bores, or painted on the outside of the block which represent selective fitting of pistons and bearings. It is and was done all the time.
 
We should all be so lucky to find a block in that condition after all these years! I'd like to have a few of those!
 
The bore is finished to the piston to get the proper clearance. So your pistons are small. Not that big of a deal. You measure the pistons first. You don’t bore it to 4.32 and then measure the pistons.
Don’t take it in and say bore it to 4.32. Have the bore size fitted to the pistons for proper clearance.

You are very Lucky to have such a good bore with no wear. Don’t pull your hair out, it will come out on its own in the coming years. LOL
Im 48...been watching the hair leave my melon for the last 20 years..lol
 
Blocks and cranks normally have "selective" parts to set the appropriate clearances. They aren't going to send a block or crank back to get re-machined when the size isn't optimal. A lot of engines are stamped by the bores, or painted on the outside of the block which represent selective fitting of pistons and bearings. It is and was done all the time.
So safe to say we are headed to the machine shop then...
Time to put it back on the "back burner" and get the 383 ready to go.
 
4.317, close enough for Chrysler LOL!
When you get the paint off it look for big paint letter marks under the bores " A B C D" etc. That denoted different sizes.
Here is my '78 block...it was marked "B B C C". Kinda hard to see what's left of them, but they were there.
I doubt any factory blocks were a perfect 4.320 on all eight. That wreaks of effort...
20200428_2012231.jpg
 
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