BB piston rings

[Nacho-RT74]

Just to be sure ( once again ).

I can use .020 440 piston rings on a 400 standart measure... right ?

I got long time GOOD PRICED 440 Chrysler .020 rings suposelly Premiun set ( so I guess moly ) in just $20 or so and I have allways though use it on my 400 refreshening job with my KB240 new standart pistons

These pistons rings have a lates 60s PN ( PN 28xxxxx as far I recall, so around 67/69 year PN )

I'm allmost ready to begin the engine new assembly job whith these parts

[Cooter]

I don't know bout that...I would be concerned with the ring gaps closing up on me after it got hot...Why not just pop it .030 and run the correct rings?

[Nacho-RT74]

Engine doesn't need to be bored ( just checked it ) it has barelly around 25K miles on an sleeved 400 block. KB240 pistons were already around, in standart size to match my engine.

Of course ring gap will be checked.

but wondering and wanting to be sure numbers aren't wrong

if standart 400 is 4.34" and standart 440 is 4.32... then .020 440 is 4.34 too... right, and is matching the standart bore on a 400.

( I have known in fact you can install lates/smogger 440 pistons on a 400 too and will get around .010" CH more than with KB240s )

[Cooter]

440 Pistons in a 400? Not unless you want them to slap like hell....(.020 too lose)

[John_Kunkel]

+.020" 440 rings are the same as 400 standard as long as the width is the same. Rings are sold by size as well as application.

[Nacho-RT74]

Thanks John. Logic and numbers says that, but I just wanted to be SURE I'm not missing something

[Nacho-RT74]

440 Pistons in a 400? Not unless you want them to slap like hell....(.020 too lose)

Of course I'm talking being 440 .020 oversized to fit on standart 400

[Cooter]

440 Pistons in a 400? Not unless you want them to slap like hell....(.020 too lose)

Of course I'm talking being 440 .020 oversized to fit on standart 400

"( I have known in fact you can install lates/smogger 440 pistons on a 400 too and will get around .010" CH more than with KB240s )"

Late "Smogger" 440 pistons most likely aren't gonna come in at .020 overbore. SO, I read your post as you were using STOCK pistons in each engine...
Also, I can't see late smogger pistons in anything getting more compression Hieght (CH) than any aftermarket piston except a set of blower pistons...

[Nacho-RT74]

I have been searching info about this stuff latelly after heard about that and looks ist somehow "doable"

here The piston CH stated on stock replacement pistons for smogger 440s is 1.912" ( PN 424P )

http://www.campbellenterprises.com/mopar_sealed_power_cast_pistons.htm

KB 240s are 1.908

http://www.kb-silvolite.com/kb_car/performance.php?action=details&P_id=22

The max CH posible on a 400 Block stated here is 1.935":

http://victorylibrary.com/mopar/deck-height.htm

so although we know the block deck height must be checked, with tolerances and correct cut as factory spec looks is not some CRAZY to do

[Challenger340]

Whats this all about ?
Putting .020"over 440 RINGS, in a std Bore 400 ?
or,
using .020 Over 440 PISTONS, in a std Bore 400 ?

Piston "Compression Heights", are from the Pin Center to the TOP of the Piston, and MAY work ?
However,
RARELY, are the Piston SKIRT designs, BELOW the Pin the same ?

Careful that those 440 Pistons don't BANG into your crank Counterweights ?

[Nacho-RT74]

actually initially it was just about the rings

but then thread turned out in something else with more info

skirts... maybe it could be modified if longer. With care to not afect balancing I think

I'm just thinking out loud, not saying I will make it. I already have the KB pistons, but those would be another options for 400s

[flyinlow]

Rings should work. 1973 FSM shows 400/440 piston rings the same dimensions,except for length for different bores. So if the KB pistons use a standard size ring . a .020 over 440 ring should work.
Stock smog 440 pistons weigh 857 gms.  400 pistons with a bigger bore only weigh 768 gms. I would guess the 400 piston has a shorter skirt. I have never seen them side by side however.   

[Challenger340]

I've modified 340 Forged Pistons, BACK IN THE DAY when none were available for 360's, (thats how old I am LOL !), to work in a 360.
It involved Milling the Piston Tops down, re-cutting the flycuts, and then making up a skirt "recontour" pattern from sheetmetal that was placed in a Vise, and held the piston for re-work to fit the Crank Counterweight on the longer 360 stroke.
Then a rebalancing job complete of course.
Heck, BEFORE THAT, we even modified 327 Chevy Flat-Tops to fit, trying for a 360 internal Balance piston, using some .990" BBChevy Lightwt Superstock Pins !
That said,
THESE DAYS,
and not being as "Nuts" as we were back then ?
I just can't see doing it to a set of 440 Pistons to fit in a 400 unless a guy was really bored ?

Put it on the back shelf Nacho, play with it sometime, just for Fun if at all ?

[Nacho-RT74]

well, if you think 400 owners doesn't have more options than KB240s or stocks ( beside custom made ) so it is more less what back in the days you made with the 360 you built, and 440 smogger flat tops won't have the valve reliefs ( so 5 cc less ), is not THAT crazy, and yes, will be some "fun" if somebody with experience and tools want to play.

Of course I will be playing with my KB240s, won't get into deeper waters about custom job involved, but IT IS definitelly an option I think.



( even better if somebody find a cheap but perfect conditions used 440 smogger piston set to play )