360 stroker kit in 340

-
D

Dillon Crowell

Active Member
Joined
Jan 7, 2022
Messages
33
Reaction score
3
Location
Georgia
Is this something that is possible besides the pistons? Found a super good deal on Facebook for 360 kit but I’ve got a 340. Just wondering if it’s compatible
 
t.he 360 crank has a bigger main bearing journal so it won't fit a 340 block .
 
Last edited:
Dillon Crowell said:
Is this something that is possible besides the pistons? Found a super good deal on Facebook for 360 kit but I’ve got a 340. Just wondering if it’s compatible
Click to expand...
318-340 and 360 mains are different size. 340 mains are 2.500 where 360 mains are 2.810 so no, it won't work.
 
Pistons may also be an issue aside from the main journal issue mentioned above.

340 stock bore is 4.04” so it starts 0.040” bigger than a 360 stock bore of 4.00”. What bore size does your 340 need to be and how does that compare to the piston size in the 360 kit? They are likely too small.
 
You could have the main journals of the crank turned down to fit in the 340 block. If the pistons are 4.060 or 4.070, you can make it work. If it were me, I would buy a cheap 5.9 Magnum block and use that.
 
Many moons ago, that was a way to make a stroker... 360 crankshaft with the mains turned down to fit a 340 block... it resulted in a 372 (I think) cubic inch engine. My friend went this route with w2 heads. It ran really well. I believe some manufacturers are making these...

Something to think about
 
Mopar Performance sold 3.580 stroke cranks with 340 - 2.500 main journals so with stock rods and custom pistons you got 372 cubic inches.
 
If I live long enough to get around to it, I'm going to rebuild the numbers matching 318 for my 71 Challenger convertible and use a 3.58 stroke crank. .030 318 with a 3.58 arm on the crank makes a 349.
 
Tom Hoover put 360 cranks in 340s decades ago, so yeah it can be done.
 
Swinger 340 said:
Pretty much anything is feasible, but is it practical?
Click to expand...
I'd say just as practical as turning down a 440 crank and putting it in a 400 block for a 451. Why do people get skeered and argue about doing the exact same thing to a small block? I don't understand.
 
It would have to be pretty cheap, piston are unlikely to fit, crank has to be modified $$$, so you get rods and a crank, can you buy new piston, get the crank modified and get some $$$ back selling the 360 pistons, do you save enough money to make it worth while ?

Like most others say buy it and a 360 block, save the 340 for another build or sell that, worth a few $$$.
 
273 said:
It would have to be pretty cheap, piston are unlikely to fit, crank has to be modified $$$, so you get rods and a crank, can you buy new piston, get the crank modified and get some $$$ back selling the 360 pistons, do you save enough money to make it worth while ?

Like most others say buy it and a 360 block, save the 340 for another build or sell that, worth a few $$$.
Click to expand...
I don't disagree there are probably cheaper and easier ways, but some here have said "no it won't work" and that's simply not true. If somebody needs to use what they have, it most certainly can be done. I forget which pistons Tom Hoover used, though I remember they were positive deck height, but he used an off the shelf piston. @oldkimmer might know.
 
RustyRatRod said:
I don't disagree there are probably cheaper and easier ways, but some here have said "no it won't work" and that's simply not true. If somebody needs to use what they have, it most certainly can be done. I forget which pistons Tom Hoover used, though I remember they were positive deck height, but he used an off the shelf piston. @oldkimmer might know.
Click to expand...
Oh I 100% agree the crank can definitely can be made to work, turning the mains ain't that big of deal.
 
Pistons will be off the shelf. Since the 340 and 360 blocks share the same deck height, all you need to do is get the pistons in the correct over size for the 340 block. The only "custom" work is turning the main journals down on the crankshaft.
 
You can use off the shelf pistons to do the 349 too. Gotta rebalance it anyway, so just turn the counterweights down to clear the skirts and neutral balance the whole she-bang!
 
JDMopar said:
You can use off the shelf pistons to do the 349 too. Gotta rebalance it anyway, so just turn the counterweights down to clear the skirts and neutral balance the whole she-bang!
Click to expand...
I like the idea of the 349, with all the aluminum headed 408s out there, taking somewhat discarded parts (360 crank,heads,318 block) and make something out them, a 349 close enough to a 360 shouldn't be a huge power difference especially if you can bore out the 318 to 4" but seems like a hard way to give up 0-18 cubic inches. Could see if you had an engine machine shop maybe and to me the main reason to build a 318 is 3.31" stroke and rpm.
 
Last edited:
True, but I'd like to get the numbers matching motor back in my car. The little extra stroke with the added cubes will help the lard *** Challenger conv get out of its own way quicker...lol.
 
JDMopar said:
True, but I'd like to get the numbers matching motor back in my car. The little extra stroke with the added cubes will help the lard *** Challenger conv get out of its own way quicker...lol.
Click to expand...
Makes sense.
 
You must log in or register to reply here.
-

Back
Top