FactoryFreak

iTrader: (2)

I was wondering if it is even possible to take a stock roller block and just change the crank to a 383 crank and not change the rods or pistons. I'm sure there would some things you would have to change, but what?
Thanks

RB83L69

No.

The rods and/or pistons.

Think about it.... if the stroke is longer, that means the pistons will try to come out the top of the block. They'lll hit the heads.

A SBC block is 9.025" from crank centerline to deck surface, more or less. In a typical factory motor, the pistons come up to about .025" from the deck surface. That means that the rotating assembly has to be exactly 9.000" tall. You'll find that it is; in a 305 or 350, the stroke is 3.480", the rod is 5.700" long from center to center, and the piston pin center is 1.560" from the top surface of the piston. So, the pin height, plus the rod length, plus half the stroke, you'd expect to come out to 9.000"; and in fact it does: 1.740" + 5.700" + 1.560" = 9.000".

If you change the stroke, one or more of the other dimensions has to be changed also, to keep the sum of those 3 numbers equal to 9.000".

Streetiron85

Or you could get a plate of steel that's machined perfectly flat on both sides .100" thick (depending upon your gasket thickness) and drilled / bored to perfectly match all the holes in your deck, and then sandwich that between 2 head gaskets before you bolt the heads down, to increase the deck height.
But then you'd have to put spacers on the intake gasket surface too.

Easier to just buy a set of rods and/or pistons.

Chris89GTA

iTrader: (2)

I can't say I have ever heard of that...

Are you freakin kidding?? I hope so...

Streetiron85

I never heard of it either.... it's just something I thunk up.
Although, some guys who were into building stroker Harleys used to use "stroker plates" which didn't amount to much other than a spacer under the cyl jug, to increase the deck height.

Chris89GTA

iTrader: (2)

I have heard of it on motorcycles too... but not on V8 stuff... who knows... I just don't think I would do it.

Streetiron85

Well... with a stroke of 4.25" X 4.155" bore, I just calculated that you could get 461ci.
The deck height could be increased by adding a .125" spacer between the block and head, and the rods and pistons from a 434ci stroker could be used.
.... Why not ?? I'm sure it would be a strong running engine, for a while at least.


I cant believe I'm posting this

ME Leigh

Build it please,.... just remember you'll need 4 head gaskets, and some intake spacers.

Stekman

A tube of RTV is handy, too.

Streetiron85

For the cost that the custom machine shop labor would set you back, a guy could probably buy a bridgeport mill and perform the labor himself. And if the project proved successful, produce and sell kits for tall deck SBC retrofits.

I'm not gonna be able to sleep tonight :lala:

OMINOUS_87

Uh lets not forget the obvious here.

Tossing in a stoker crank without having the block machied to hold it and you will never turn the motor over.

Now a stoker plate is just damn silly.

Buy a kit, do it right, what the hell yall smokin to hatch some of these half baked ideas???

THEGENERAL

my goodness whats goin on in here ...lol...i hear stuff about 4 head gaskets and shims to make a 383 crank fit ???? WOW......lol...it must be bed time or somethin well im gonna hit the hay before we start talkin about weldin the heads to the block so you dont blow headgaskets or something stupid like that..LMAO>...... :werd:

Streetiron85

It's gotta be the full moon.... I'm not smokin anything

Stekman

That would depend. You can buy pre-fitted 383 cranks with the mains already ground. but yep, the pistons need to be 383 designated as well. With the given piston height of a 350, if you add a 3.75 stroke, you will push the piston over the top of the deck.

Oil pan rails need grinding as well. Mine did.

On a side not, i too, would like to see this stroker plate made.

Streetiron85

Stekman, you meant on a side note... right?

Hmmm....
Assuming a part like this actually proved itself to be functional / reliable....
What applications might it be useful for?
By a enabling builder to increase the deck height, it could allow the use of a piston with a taller compression ht, a longer rod, or a longer stroke than the stock block would. True.
But in fact, it's probably the least practical way of getting around the issues of inadequate deck height, considering the parts are already being produced to fit stroker cranks into stock blocks.
Unless a builder starts approaching the outer reaches of increasing the stroke, and isn't interested in investing in custom made rotating assy pieces. Or wishes to keep the taller compression ht/ longer rod combo.
Basically... A lot of knowledgable guys would argue that it makes no sense. Cause when you get into the really big stroker setups, parts hitting the sides of the block would become the limiting factor, anyway.
But still, if I had a machine shop, I might actually try the idea out anyhow. If it meant I'd be able to turn my 383 into a 406 by just swapping the crank.
(can a 4" crank even fit into a stock block?? ...I dunno)
The idea that really excites me tho, is an aftermarket tall deck alum block.
The 461 SBC is within $$$ reach!
As long as we're dreaming, might as well Dream Big!

Stekman

Yea, i meant side "note."

on side NOTE, there is no "c" in my name

Streetiron85

There... all fixt

If I ever get a mill, I'll whip out a prototype and let you know how it worked.

I'm not gonna pollute FactoryFreaks thread anymore with my whacko mad scientist ideas.

SweetS10v8

Stroker plate, lol

OMINOUS_87

Link me to one of these types of cranks. I am not calling you out or anything its just that I have never heard of this before and havent been able to find any. We are about to slap another 383 together for a buddy and if these cranks are avialable we might just buy one and save the hassle of clearancing the block.

Thanks

five7kid

iTrader: (14)

If it's being sold as a 383 crank, the mains have been turned to (or started out as) the 350 size.

You always have to clearance a 350 block for a 3.75" stroke crank. What the mains are ground to doesn't have anything to do with that.

Stekman

five7 is right. By pre-fitted i meant a crank that has already been setup for 350 mains. That is all. It has little to do with block prep.

OMINOUS_87

As I said origianlly, my statement had excatly nothing to do though with crank mains however, when you opted to corect the statement.

Cant stuff a 383 crank in without doing this first.

OMINOUS_87

Exactly right.

Without machining the block the motor will never turn over, for obvious reasons.

THEGENERAL

LOL if you dont machine that block your gonna have a big problem real quick ...LMAO