looking to build and small block stroker motor should I do a 360 or 340 what is the difference?

The main difference is the bore... a 340 base has a larger bore
and will give a few more cubes... but 340 blocks are harder to
find.. plenty of 360 blocks.. I like the big bore for after
market heads with larger valves to help unshroud the valve

Really depends on what you're trying to accomplish. 340 blocks are hard to find and expensive so doubt you're going to use up one of them just for a bracket car. The 360 uses different crank and oil pan. Aftermarket blocks can be either 360 or 340 crank and oil pan. Stroker cranks are made in either flavor although I think the high performance stuff is usually 340 mains while the lower cost stuff is typically 360 mains.

Everybody always says 340 blocks are hard to find.
No they aren't. You see them everywhere 500-700 dollars typically. Sometimes cheaper.
As far as " using them up" who cares.
Better than sitting and rusting on some garage floor being wasted. Life is too short. If they don't get used what good are they?
For a typical 5,000 to 10, 000 dollar stroker build( or more) from start to finish, for the small difference in price between the 340 and a 360 block in the whole scheme of things, it's crazy to not use the bigger bore, more cubes advantage of the 340.

My 1st preference would be a early 360 with the thicker walls,cast date late 70 to 73, bore it to .030 over. 2nd would be any year 340 that sonics OK but bore it the absolute minimum if it will clean up at.010 or .020 GREAT! after that any year 360 that passes sonic but also bore the absolute minimum.

.. what size stroke are you thinking of using?

My first and only preferance is the 360 magnum block. It is the strongest readily available block, most consistant bores even if they are a little thinner than an early 360 in the thick areas but that early 360 is more likely to have thin areas because of casting shift and 40 years of neglect. The easy to use and very cheap hydro-roller cam in the magnum trumps .040 bore size any day of the week. The block it self is very cheap, I have a couple I would sell for $100 ea. I usually get cores for $150. I don't have any hardness tester except my die grinder and it does not like grinding bore notches for a stroker in a magnum compared to an older block. Around here it is hard to find a 340 much less a 340 that is for sale. If I could get a decent 340 block for $500 I would snatch it up real fast to flip it to a restorer, hard to pass up a chance to double my money.

I will start looking in to the Magnum 360 blocks for future builds. I have been building LA blocks ( earily and late E58 blocks ) simply because they were available to me at the time. Not sure on the validity regarding early blocks being thicker than later ones? Ran a 71 block out of a motor home and two 79 E58 blocks. All sonic tested real good. IMO, always best to start with a known "virgin" block ( never been apart before ) if you can. If the OP is not building real high end or odd ball, there are many dealers out there that sell "drop in" rotating assembly's based on the HP level you are lookin for. Makes it easy and eliminates first timer errors. Your machinist can really help you out in this area and often save you a lot of $.

Either one, I like the earlier 68-71 blocks generally. Never built a Magnum block but I see no reason not to other than I heard you don't want to punch them more than .020-.030.

Presently I have both a 340 based 414 (4" stroke) and a 360 based 440 (4.25" Stroke).

340's can still be found but they are typically 3X what a decent 360 core will cost you, not really worth it unless you're doing a resto sleeper or numbers matching. The 360 has larger mains which is an advantage on the 4"+ strokes in terms of journal overlap, the downside is higher bearing speeds but generally a 4+ stroke you won't want (or really need) to turn it too high anyway.

I used a 1990 360 LA block for my stroker build because it already had the bosses for the roller cam. I used stock Melling lifters and saved a ton.

360 magnum blocks FTW!!!!!!

620hp Stroker 360 for 11k? I'm intrigued..

http://www.hotrod.com/how-to/engine/ccrp-1110-pump-gas-small-block-mopar/

exactly what it cost me to get 610hp........

Dan

My 416 made 590 on the dyno.. its just a throw together
with stuff I had in the shop... W-2 heads with a .640
lift roller cam and 10.4 compression.. its in my Rampage
so its a street/strip car.... thats a 340 block... the only
parts I had to buy were the pistons because of the lower
compression.. all my other pistons were in the 12+ range
EDIT
that was on 93 on the dyno... on the street I run 87 octane