help 318 and 340

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same and will interchange, as i have been told
 
David William Elder wrote: "If you compare an early (such as 1968) 340 crank to a 318 crank of the same vintage you can clearly see the 340 casting is beefier. I think the two are the same numerically speaking but as far as strength the 340 is clearly the winner. The same goes for the connecting rods. The 273-318 connecting rods are similar to the 340s but a different casting with less 'beef'. I have actually seen some mid-70s truck and stationwagon 318s that came from the factory with 340 Six-Pak rods."
Read more at http://www.allpar.com/mopar/318.html?ktrack=kcplink
 
so you cannot use a 318 crank in a 340???????????????????????? well, i was told from amember here that i could. so i must now yank the engine all apart..lol j/k
 
Dude, the search button is your friend. :-D

They have the same main and rod size, so they can be interchanged. If your swapping crankshafts you should have everything balanced anyway.

'68-'71 340 crankshafts are forged, while the majority of 318 crankshafts are cast. Not all though, early 318's and truck 318's had forged crankshafts too.

Haven't seen like types side by side (ie, 340 forged vs 318 forged) to say whether or not the 340 cranks are better. I would imagine the later '72-'73 340 cast crankshafts are the same as the 318 cast crankshafts. But, again, I haven't seen them side by side.

The next question is, why? Are you swapping a 340 crank into a 318 for more strength? Or looking for a replacement 340 crankshaft? I would think that even a stock 318 cast crank would have no issues handling up to 400 hp, so, I don't think I'd worry about putting a stronger crank in a 318 unless I was planning on racing. Pretty much the same for the 318 crank in the 340, I wouldn't worry about it unless I was making 400 + hp or racing.
 
To give you an idea of how strong the old cast cranks are, I ran one in my 340 with a solid cam and 10.5-1 comp...turning past 7000 with a 4 speed in a 69 swinger. No problems. The engine was built and balanced, not just bolted together. It used stock rods and stock style forged pistons. My next one will be a forged aftermarket crank and rods (k1 maybe) and some light 8.5 or 9-1 forged pistons. This is for a turbo build with a solid or solid roller cam.
 
i was looking at stroker kit the 340 kit were cheper then the 318 and i could not find a difference
 
3.91" is a 318 stock

4.040" is a 340 stock


You have a 318 and want to stroke it or ??
 
why are the rod bearing 2.00 what is the benafits

SB Chrysler 340 4340 Forged Steel Stroker Crank 4.125 Stroke 2.000 rod journal 4.125 2.000 small block Chevy small journal size
 
i have a 1973 318 complet it came out of my car it ran 80,000 miles im wanting 500hp i also have 2000 360 mag that i could use im try to look at all opps.
 
1wild&crazyguy said:
but get some real heads cause the rockers and roller cam only offset the crummy flow, then where is the advantage in that.
Click to expand...


I just get sick of arguing with the guys who have magnum heads, and say they are the ****, they don't all crack, use chevy parts so they are cheaper, and make 900HP on pump gas.....
 
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