340cui with .070 bore

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Chrippa

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Hi everyone!

I recently bought my Duster from the US!

The previous owner told me that he had bored the 340 that sits in the car .070 and stroked it to 412 cui!
The stroke kit came from Hughes Engines!

Has anyone tried this kit out and how bad is it to bore that much? What i heard you should not bore the 340 standard block more than .040 ?

Hope someone knows :)

Cheers! // Chrippa
 
If its a 4" stroke crank with a .070" over bore you'll have 425 cubes. A 412 would be a 4" crank with a .010" over bore.

To know how far a block can go safely it would need to be sonic checked.
 
AdamR said:
If its a 4" stroke crank with a .070" over bore you'll have 425 cubes. A 412 would be a 4" crank with a .010" over bore.

To know how far a block can go safely it would need to be sonic checked.
Click to expand...

Thx for the quick response!
Yes it is a 4" stroke crank! I havent checked the bore yet but i plan on doing it while my heads are of, and at the same time sonic check the block!
This is the crank kit i have by the way http://www.hughesengines.com/crank_kits/408crankkit.asp

By the way how do you count the bore? Is it .070 on the radius or diameter ?

How much was the 340 bored from the beginning ? I read it was 4.04" , is this right ?



// Chrippa
 
340's had a factory bore size of 4.04. When overbored the amount comes off the diameter, bored .070 equals 4.110. Like adamr said sonic checking should be done in order to be sure of wall thickness. I've taken a high compression race engine to +.060 with good results without sonic checking but consider it lucky that it lasted well. A partial fill with block filler may help the cylinder walls a little also.
 
AdamR said:
If its a 4" stroke crank with a .070" over bore you'll have 425 cubes. A 412 would be a 4" crank with a .010" over bore.
Click to expand...

i think the 340 with a 4" crank is 416 with the standard bore alone. the 360 comes out to 406 with the standard 4" bore and the 4" stroke. so the 340 .010 over should be more than 412
 
BadAssDodge said:
i think the 340 with a 4" crank is 416 with the standard bore alone. the 360 comes out to 406 with the standard 4" bore and the 4" stroke. so the 340 .010 over should be more than 412
Click to expand...

actually it is 416 at 4.07 +.030 412 is .010 over

steve
 
My guess is that it is bored to 4.070" which is .030" over the standard bore size. And yes, this would net you 416 cubic inches.
 
GotDart said:
My guess is that it is bored to 4.070" which is .030" over the standard bore size. And yes, this would net you 416 cubic inches.
Click to expand...

That makes sense!

I just checked the bore metric style and it showed 10.32 cm which counts as 4.070" so GotDart was right :)

Im gonna go sonic check the block anyway just to be sure ! :)

Question: How do you count the 416 cui ? Stroke X bore etc ?

Chrippa
 
that's where i'm at. 340 block .030 over = 4.070 x 4.00 stroke = 416.:thumblef:
 
bore x bore x stroke x .7854 x #cylinders = cubic inch displacement.

4.070 x 4.070 x 4.0 x .7854 x 8 = 416.32231872 this would actually be a 417 as any fractional amount of a cubic inch is counted as a cubic inch. At least as far as NHRA is concerned.
 
Hey guys what is the standard stroke for a 340?? You guys got me wondering what my displacement is with a 340 bored .030" over with a standard stroke.

Also if your worried about cyclinder wall integrity you can always sleeve the block for extra strength like i did. >:)
 
TheCrazyCheesehead said:
Hey guys what is the standard stroke for a 340?? You guys got me wondering what my displacement is with a 340 bored .030" over with a standard stroke.

Also if your worried about cyclinder wall integrity you can always sleeve the block for extra strength like i did. >:)
Click to expand...

3.31 stroke and a .030" over bore is a 346
 
Thx everybody for the answers , now i know more about this than i did before ;)
 
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