318: .030-.050 over and Stroked to 340

[racerdude5]

With a bore of .030 - .050 over in a 318, what crankshaft do I need to make it have a displacement of 340? What's the best?

 

[RustyRatRod]

At .030 over with a 3.58 stroke (stock 360) you'll be at 349.

 

[70aarcuda]

With a bore of .030 - .050 over in a 318, what crankshaft do I need to make it have a displacement of 340? What's the best?

get a 4 inch crank and skip to 390 cubic inches...by the time you cut the crank and find pistons that fit correctly you will be money ahead .....

you can buy a 3.58 stroke crank with 318/340 mains...it is the same cost as the 4 inch crank...

there are a couple of cast 318 pistons that work with the 3.58 stroke but need the pin boss cleared so they dont hit the crank....

no substitue for cubic inches....

 

[RustyRatRod]

Or you could simply find a 318 block that'll bore to 4.040. They're out there.

 

[70aarcuda]

Or you could simply find a 318 block that'll bore to 4.040. They're out there.

cheaper just to find a 360 engine

 

[RustyRatRod]

cheaper just to find a 360 engine

I agree a bajillion percent, but that ain't what he asked. lol

 

[70aarcuda]

I agree a bajillion percent, but that ain't what he asked. lol

that is true....just suggesting a cheaper atlernative......

 

[MRL Performance]

318 and 340 have the same stroke crank. Do worry about the CI so much. A well built 318 will hang with a 340 that is built the same. CI doesnt really matter. Its just a number.

 

[Robbie2734]

318 and 340 have the same stroke crank. Do worry about the CI so much. A well built 318 will hang with a 340 that is built the same. CI doesnt really matter. Its just a number.

YEP, what he said. Put your money into the 318, you can make it a monster!

 

[dodge freak]

I disagree, the extra bore of the 340 allows for better flow using a 2.02 or larger intake valve. You could notch the cylinders on the 318 but it still be 20 CI short. When 15 extra hp can knock off .01 a Q mile et that extra 20 CI could win a race you otherwise would lose

Sure a 318 can crank out the power but built the same the 340 will eek out ahead

 

[racerdude5]

Am I gonna' need longer rods with a 3.58 stroke?

 

[DJVCUDA]

no - all small blocks used a 6.123 rod

 

[racerdude5]

Would there be a benefit of longer or shorter rods?

 

[MRL Performance]

Its complicated and if your not 100% into building the ULTIMATE engine, dont worry about it.

CI does matter, but when it very close, like 20ci, its not that much difference. But a 318 and 340 built the same will run just about the same.

.01 quicker in the 1/4 for a 340 over a 318? Thats hanging with a 340 in my book.