340 crank in 360

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husker2733

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yah I was wondering if you can fit a 340 crank into a 360, if so is there any modifications needed to do this. thanks, Eric
 
Why do it...to rev the piss out of it.

You can make a "stock 340" by boring it .040 over and using stock size 340 pistons. True a built 360-with forged crank, H rods, ect will live at 8,000+ rpms but if you have a good forged 340 crank lying around these spacers allow you to use the crank.

Smaller mains are better for high rpms.

Some race motors see 9,000+ rpms

http://chucker54.stores.yahoo.net/mabesp.html
 
Yah I have a 340 forged crank laying around. What would be the advantages and disadvantages of doing this. Thanks, Eric
 
It be a cheaper way to run a forged crank for high rpms.

But after buying the spacers and likely a line hone-if not bore-not sure how much cheaper. Scat forged cranks are around $700 and plus you get more stroke.

But stroke isn't what you want for high stress-high rpm racing motors..like oval track. Street motors are far different. Those motors you don't run a 5,000+ torque converter, 13 to 1 compression and shift at 9,000 rpms.

The disadvantage is you lose some torque by running a 3.31 stroke crank instead of a 3.58..

BTW in 1970 the 340's were de-stroke to get in the 305 CI rule requirements. The racers could had sleeved the cylinders for smaller pistons and still have the 3.31 stroke but they went for using a 2.94 stroke crank to gain rpms and less stress on the cylinder walls. (bet some old timers are shaking their heads at running a 4 inch stroker crank, lol)
 
dodge freak said:
It be a cheaper way to run a forged crank for high rpms.

But after buying the spacers and likely a line hone-if not bore-not sure how much cheaper. Scat forged cranks are around $700 and plus you get more stroke.

But stroke isn't what you want for high stress-high rpm racing motors..like oval track. Street motors are far different. Those motors you don't run a 5,000+ torque converter, 13 to 1 compression and shift at 9,000 rpms.

The disadvantage is you lose some torque by running a 3.31 stroke crank instead of a 3.58..

BTW in 1970 the 340's were de-stroke to get in the 305 CI rule requirements. The racers could had sleeved the cylinders for smaller pistons and still have the 3.31 stroke but they went for using a 2.94 stroke crank to gain rpms and less stress on the cylinder walls. (bet some old timers are shaking their heads at running a 4 inch stroker crank, lol)
Click to expand...

Two different animals, totally. Those high revving, short stroke motors, are a blast when they get in their power curve and are making horse power. But the 4" inch crank totally changes their personality into a torque monster.
I haven't personally owned a 4" inch stroker, but I drove my buddies, and wow.

I built the 3:51 stroker 340, and it is different yet. It starts make HP and winding almost like a 340i, but it has much more torque.

That being said, I just picked up that 89 318 today, to put in it's place for a while. :toothy10:
 
Use the spacers... why, that's for you to understand. But you need to run the bearing spacers to run the 340 main crank in a 360 block.
 
HemiEd said:
Two different animals, totally. Those high revving, short stroke motors, are a blast when they get in their power curve and are making horse power. But the 4" inch crank totally changes their personality into a torque monster.
I haven't personally owned a 4" inch stroker, but I drove my buddies, and wow.
Click to expand...


Yes for the street--and maybe some racing use--the 408 stroker is the way to go. Its drawback --if any--is its red line limit. Build right with all forged stuff and great machine work and a sound block a 408 stroker might be ok to 8,000+ rpms. Still if you were to run both motors at 7,000+ rpms the 305 would last much longer...408 would make more power due to the large increase in CI.

You take two engines at the same CI the short stroke motor will make more HP if revved high enough. (at least what the racers I trust have to say)
 
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