409 pistons with holes on the skirt

[Ckruse59]

I have a used set of forged pistons and they have holes on the side. They came with plastic plugs for the holes. The guy I got them from didn’t know much about them. I’ve never seen anything like this . Anybody help me out here ?

 

[Ishiftem]

I think they were used to take up space in a cold engine with large clearances yet allow the piston to grow in a high heat application without scuffing. Old tech but still think it’s used in some odd ball applications.

 

[Don Jacks]

I think they were used to take up space in a cold engine with large clearances yet allow the piston to grow in a high heat application without scuffing. Old tech but still think it’s used in some odd ball applications.

Dan's 100 percent right.A 409 given it's large bore would,on those "Old Tech" forgings would run a piston/wall clearence of around .016 cold.They were meant for racing only so cold slap wasn't a concern.Those things,like the forgings in the Chrysler Max Wedge engines[.014] grew a lot.I wouldn't even consider running them in any kind of application today.Wall art.

 

[63 dream'n]

So why the knurling on a brand new piston......????. knurling is used to achieve an oversize......?????..

 

[La Hot Rods]

Hold oil to lube the button's

 

[Ishiftem]

That would be my guess.

 

[tenxal]

I have a used set of forged pistons and they have holes on the side. They came with plastic plugs for the holes. The guy I got them from didn’t know much about them. I’ve never seen anything like this . Anybody help me out here ?

Those are for skirt buttons....similar to the Teflon pin buttons.

 

[Ckruse59]

Dan's 100 percent right.A 409 given it's large bore would,on those "Old Tech" forgings would run a piston/wall clearence of around .016 cold.They were meant for racing only so cold slap wasn't a concern.Those things,like the forgings in the Chrysler Max Wedge engines[.014] grew a lot.I wouldn't even consider running them in any kind of application today.Wall art.

 

[Ckruse59]

I appreciate your input because I was lost. What’s the main reason you would not use them in today’s application? Is it simply because there are more modern better pistons available? Just curious

 

[Don Jacks]

Yes today's modern pistons are stronger,lighter,and run much tighter piston/wall clearances than the old stuff did.Example,A N/A W engine for street/strip use on pump gas will be in the .005-.0055 range as opposed to those old tech/material like you have there which will require .015-.017 piston/wall.Wide wall clearences will mean more piston rock,more ring scrub,which means lost power,shorter componant ,engine assemby life.Just not worth fooling with as these engines are too hard to come by.

 

[Ckruse59]

Yes today's modern pistons are stronger,lighter,and run much tighter piston/wall clearances than the old stuff did.Example,A N/A W engine for street/strip use on pump gas will be in the .005-.0055 range as opposed to those old tech/material like you have there which will require .015-.017 piston/wall.Wide wall clearences will mean more piston rock,more ring scrub,which means lost power,shorter componant ,engine assemby life.Just not worth fooling with as these engines are too hard to come by.

 

[Ckruse59]

I understand now. Thanks for taking me to school.