Used 340 vs Summit Racing 340 Race Block

[Mopar Monster]

I'm having trouble making a decision on an engine build.  I've been thinking about finding a used 340 block to build a high horsepower street engine.

I'm not interested in a 350 horse 340, I'd like to build something more fun.  No it's not a budget build I have both time & $ to get this done.

I have located several different 340 blocks, I don't think they are as rare as people make them seem to be.  A few of them claim to be stock bore & there are a few @ .020 to .030 bore.

Prices near me are 1000 +\- on 340 long blocks.

Considering this info, I'd like some insight on how best to approach a solid 340 high performance street engine build (7,000 rpms).

..................................

After mag checks, zero decking block, machine work, 4 bolt main caps,,,, etc..on a 45 year old short block..  Is it better to buy a summit racing brand new block?

http://m.summitracing.com/parts/dcc-4876673ad?seid=srese1&gclid=CM-fo4i6hMoCFRRlfgodBacA-A

What kind of performance can be had from an original 2 bolt main (.030 bore) 340 vs a 4 bolt main new block?

I can get the factory crank but may require some work, so an aftermarket crank w/ rods & pistons would most likely be used on either block.

Let's hear some input on going with OEM block vs virgin modern technology!

[7212Mopar]

 The new casting will not take roller lifters which would be a good thing for 7000 RPM. However I think Indy can machine it to make it happen. My 340 is .03 over and I am looking at building a stroked 408 with a 360!short block or get a Mopar crate Super Commando 440.

[Chryco Psycho]

Hughes has a new block available not that i WOULD BUY THere maybe th same block but it has a lot of improvements / will take roller lifters / buy the time you mad an old block this should be a better deal .
 The webbing on stock 340 blocks will not support 4 bolt mains , only the T/A blocks or the new block listed on Hughes site

[1 Wild R/T]

The block from Summit is a 360 block, not a 340.... It is a race block so it's got four bolt mains ... Personally I'd forget the 340... Why pay all the $$$ for a 340 when all you gain is a .040 bigger bore but the block isn't any tougher than a 360 block... So that leaves either the MP 360 race block or a 87-90 360 truck block which would be a cheaper way to go and is set up for roller lifters... But if you really plan to beat on the engine the race block is likely a better call... Your money, you roll the dice... 

[Mopar Monster]

Yea I'm starting to think that the 360 is the way to go.  I've been shopping around and adding up the cost of a 340 build, I'm starting to think more of a 360 stroker now.

I have another thread going here about a 1979 360 long block I found for 100.00 usd.  It's just less expensive to go this route.

Thanks for the replies, I'm done with my 340 dreams.  Happy New Years E-Body!!!

[jimynick]

Bang for the buck, I think you've come to the reasonable conclusion regarding the 340. Had I your plans and $, I'd go 360 roller block with a stroker kit and A/M heads and you should have all the power you'd need at a reasonable price. But then, that's just my      

[Chryco Psycho]

or with a larger budget get the new block with 4 bolt mains  , cam channel , 18 head bolt , clearanced for roller lifter available in 59* or 48*  this way you can use w8 or 9 heads & push maybe 750+ hp

[1 Wild R/T]

or with a larger budget get the new block with 4 bolt mains  , cam channel , 18 head bolt , clearanced for roller lifter available in 59* or 48*  this way you can use w8 or 9 heads & push maybe 750+ hp

Everyone that I've heard of trying to use the Nascar stuff on the street has had marginal results... The heads don't work at low RPM's, no torque... And theres no room to put a big stroke in that block...  To bad cause a big inch small block with lots of head would be awesome..

[Chryco Psycho]

Finally found the thread with the new block casting .
http://www.cuda-challenger.com/cc/index.php?topic=110108.0

[1 Wild R/T]

Finally found the thread with the new block casting .
http://www.cuda-challenger.com/cc/index.php?topic=110108.0

Hadn't seen that... Cool, a big stroker with big heads is possible... If you have a liquid cooled wallet...  Cool...

[Chryco Psycho]

The first post in this thread states he is not on a limited budget but simply wants the best results so this block looks like the right piece , use some W series 18 bolt heads & you have a Killer small block builld ! This block looks like it would support  lot more HP than any 340 /360 factory piece with some great features such as the submersed cam taking the oil out to the front & rear of the block .
 426 ci or more with killer heads , what is not to like !!

[1 Wild R/T]

The first post in this thread states he is not on a limited budget but simply wants the best results so this block looks like the right piece , use some W series 18 bolt heads & you have a Killer small block builld ! This block looks like it would support  lot more HP than any 340 /360 factory piece with some great features such as the submersed cam taking the oil out to the front & rear of the block .
 426 ci or more with killer heads , what is not to like !!

Agreed... If the budget really allows it, apparently capable for being build as 482 CI... And thats what I'd do... Max cubic inches, Max torque... Don't need to spin it to 8500 rpm's like a "normal"? W8/WW9 combo..

[Chryco Psycho]

 
 Except  I would be worried about running to short pistons with long rod ratio so max CI could be detrimental to engine life & may not perform well on the street especially if the oil ring is over the piston pin for example so may 440 CI with a better piston height may work better .

[1 Wild R/T]

Yup, agreed, I'm not a small block guy & certainly have no experience with small blocks at that level.. Research would be needed before committing to a plan.... A little extra skirt on a piston is a good thing....

[Chryco Psycho]

You  could have some serious fun with that , almost 500" with W9 heads , lift the hood & yeah it is just a 340 with aftermarket heads !!!