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[308] 253 stroker internals into 308

Elscrappycoco

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hey guys I've got a 253 stroker with a crow cam roller rockers etc...
I have a 308 black motor for my vk with light scoring in bores 30thou over
Im wondering what internals would be interchangeable.. if any at all
Anybody have any ideas or played around with this before?
 

EYY

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The crank should work, as will the rods. What's the 253 bore size? Usually when they stroke them they go pretty far with the overbore (upwards of .080)

253 and 308 are the same engine apart from crank counterweights and bore-size, basically.
 

Elscrappycoco

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The bore size on the 253 is only .030 over
I'm sure it was virgin bore before he built the motor up... then never used it...
I did hear you could swap out internals but just not sure of performance and balancing issues
 

Reaper

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So you want to de-stroke a 308??? I suppose you can but wtf would you? Pistons are not going to fit.
 

Bigfella237

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More cars than I've got space to park!
So you want to de-stroke a 308???

253 and 308 both had the same stroke from the factory (3.06") so a crank that increases the stroke in one would also increase stroke in the other.

253 crankshafts have lighter counterweights to adjust for the smaller pistons. I suppose that if you could lighten the 308 pistons enough (ie. make them the same weight as the 253 pistons) then it might work?

You may also be able to get 'heavy metal' put into the counterweights to compensate if you can't take enough meat out of the pistons without weakening them (remember that the piston deck height will usually need to be accounted for as well)?

The lower the reciprocating mass, the better the responsiveness of the engine too, but it definitely won't be as smooth at idle.

Interesting concept though...

Andrew

P.S. The "cubic capacity" of an engine is simply the total swept volume of all the pistons, so...

((Area = π r²) x stroke) x No. of cylinders

If we do this calculation for a standard 308 we get...

Area of each 4" diameter piston = 12.57 square inches
(12.57 x 3.06) x 8 = 307.7136 cubic inches

So if you know the bore size that the block will end up with, and you know the stroke of your crank, you can easily work out what size motor you will have when all is said 'n done.
 

Elscrappycoco

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Hey guys thanks for replies, only reason I was thinking of doing this is I have a worked 253 and was hoping to swap out the internals into my 308, also I had the idea that a lighter crank would be more helpful in the higher rpm range, with the right head work and cam...
Although I might just hone the 308 out and slap the cam in it.. use it as is.
Only reason I posted was to see if anybody has actually done it, because I know the cams are the same
 

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253 and 308 both had the same stroke from the factory (3.06") so a crank that increases the stroke in one would also increase stroke in the other.

Duh - yeah way too long since I messed with these things :/
 

Zeke Topanaga

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You have to know what rods you have in that stroked 253 before you can find the pistons to suit, it could be any stroker kit.
Some stroker kits are for torque, towing type stuff and they have short rods and the more power type ones will use a longer rod.
 

Elscrappycoco

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Hey mate I'm yet to strip the 253 to know exactly will keep posted and go from there with it
 
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