Is it possible to use the KB 251 pistons (made for the 400/451 strokers using a 440 crank and 400 rods) with closed chambered heads? They are made with a quench pad that is meant to be machined to fit but are these pistons meant only for people using open chambered heads or can they be machined down enough for closed chambered heads as well? Thanks in advance for your help!

Sounds like the pistons that came in my shortblock. If you machine the pad off completely, you have a standard flat top. That's how mine are. Then it's just a matter of checking your compression as a standard flat top with approx 5cc for valve reliefs.

Not sure what it costs to machine them but you can probably step up to a forged flat for close once you factor in the machining.

Thanks.

It's part of a package deal on an abandoned project I'm thinking of of picking up:

400 Block (don't know year or casting number yet)
Hot tanked
Magnafluxed
Bored .060" over, honed

Not honed with torque plate.
Not align honed
Not decked yet
No cam bearings installed

Set of 060" over KB 251 pistons with rings
440 forged crank - nothing done yet
400 cast crank (not sure what I would do with that - scrap?)
Set of stock 400 rods
Pair of new Edelbrock valve covers

2 727 cores

Engine stand

All for $350

Different pistons and using the 440 rods probably would have been a better way to go maybe?

Seem like a good deal or someone else's mess to straighten out?

Ya, my pistons are for 440 rod length. Much lighter I'm sure but no reason you can't build a good shortblock from what you've got there. I'd probably buy it as long as you know that machining costs add up quick.

Line hone
Deck
Polish Crank
Resize rods w/arp bolts
Cut Piston Tops Off
Fit Pistons
Balance Assembly

I recently finished a 440 build so I know the machining costs for the standard stuff and have the receipts to look at but I don't know the costs for the special stroker-related stuff like turning down the 440 crank mains and machining down the counterweights. Also don't know the costs for machining down the KB quench pads.

Looking at old threads, it looks like a pain to get things just so with these quench pad pistons to use them with factory iron head open chambers being all over the place in their specs from chamber to chamber.

So that leaves me wondering if these KB 251 quench pads can be lopped off and made into flat tops and at what cost. He's already bored and honed the block .060" to go with this piston and ring set so they are kind of stuck with each other, no option for other pistons.

Maybe in the long run this build would save a few hundreds at the expense of being able to pick out things exactly how I would do it?

I think the best part of the 400/451 stroker is the light piston. Easy on parts, etc. This setup doesn't really take advantage of that.

Sounds like a good deal $$.
the obvious? you could always go with 906 heads? with 86 cc 11 to 1 CR page here
I have been thinking of building the same combo, a set of the 251 are on ebay now but to much for used IMO. I have a 400 ready to go. I priced the crank work and was quoted $200.00 to turn the mains down to the 400 journal size and grind or polish the rod journals. I was also told the bob weight {or weights} will need to be turned for clearance which may add to the balance cost.

I spoke to a guy at KB and he said they could be made into flat tops. Still not sure how much something like that would cost.

As soon as I upgrade my 440 to some aluminum heads, I'll have a pair of perfectly good 452s collecting dust so I could go do some home porting on them and toss them on it later to keep things low buck.

I would sell the pistons and have the 440 crank set up for the 400 motor with a offset stroke to 3.91 stroke and buy new forged, (KB, Ross or any other good name brand company with a shelf pistons for that stroke and the rod length you want to use ) pistons and new H beam rods and then beat the snout out of that combination because you can and it will live