Are all 340 blocks the same?

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If that's the case I'd go with a 340 block, I know it's a small difference but at that level extra bore will help cause you'll probably gonna want to run 2.08 valves to reach your goal. A 360 makes 500 hp around 6000 so your probably gonna have to hit close to 7000 if you run a 3.58 crank. Sounds fun. One of the reasons I'd like to build a 273 I don't need 600 hp but I'd like have an high rpm screamer, I use to love doing 8000 rpm shifts in my prelude.
 
Doosterfy said:
OK, I know its probably been discussed but I did a search and could not find the info. Anyway with that said I'd like to know if all 340 blocks are the same or if there's a particular casting number or year that's better or is there any years to avoid. I'm planning a small block build and I'm going to start looking for a good used and not used up 340 block. I don't need any info on cranks or any other parts, only the block.
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The VERY LIMITED casting T/A blocks (very late '68-very early '70) blocks did indeed have thicker webbing for the " 4 bolt Main " ... which was 4 bolt main on #2, #3, #4 only :) ...

Not withstanding the above, the T/A castings in the ? one & 1/2 yr ? had a singular
definitive absolute--- Nickel Content in the Casting ---

I.e,
All the angular block centerlines would remain constant, after having been 'flogged'
to the point of extinction in a GM /FORD build.

:) If You have the $$$$ Doosterfy,
Locate an T/A Block ...

Just My Humble opine.
 
rumblefish360 said:
Wow! Indeed it does! I like what your doing. IF I could find a thick walled 340 for this project, that is what I would be looking for. Bigger bores have a direct impact of HP. Also, the bigger the bore the better the heads like it.

The bearing speed is a low issue for most purposes. You could also modify the bearing seat for a more narrow bearing shell. This is out lines in the MoPars engines book. A book with many secrets.

The 340 block is exactly the same as a 360 block except the bore size and crank journal size. While the crank journal is larger, it doesn't make it any weaker. As mentioned before, above, where are the stress loads?
If less metal is weaker, then here is a bit of food for thought. There's less metal around the piston in the block due to a larger 340 piston. But yet it holds up great! Torque is the killer of parts far more than horse power.

N.C. is a state with many talented engine builders. If you have doubts for any reason, here at FABO there are several talented engine builders who can help you out. Mike Listen @ MRL (screen name MRL) Brain Halflinger (spelling? Sorry Brian) screen name OU812, (Cracked back can tell you about him) are a pair of fellas here.
"Moper" does a lot of engine work as well. He is a sharp (and a goodfella.)

At 13-1, are you going to run E-85?
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Yes there are lots of talented shops down here, the trouble is its mainly Ford and Chevy builders. I'm not seeing a whole lot of Mopar action down here like back in the Northeast. I'll be willing to work with a shop that's within two hours driving distance and I'll only go to a shop that really knows Mopars well. I worked with a shop back in CT when I built my 440. Guy had been building race engines for decades and had a stellar reputation with tons of circle track racers. I should have followed my gut when I saw his reactions as soon as I said 440 Mopar. Turned into a long drawn out nightmare with my engine constantly getting put on the back burner and him telling me, "you don't need this, that or the other thing". What really blew my stack was when I got it home and discovered he had failed to deck the block like I requested and then the big argument with him. He told me I don't need to deck it, just use steel shim gaskets to bring the heads in tighter. I brought it back and insisted so he did the asshole move and took over a month to do it. As far as fuel, I will be using race gas. No alcohol, just gasoline.
 
ir3333 said:
my builder also says if your going to twist it to 8000 you should stick with the 340
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Not to crap on your builder because he is right to a degree and that would be a shorter stroke engine revs higher easier and the smaller bearings take less of a beating.

However, if a 5 inch stroke engine can turn 8K plus rom, there is no reason why a 3.58 crank can not ether. Big or small bearing journals. The trick is oil feeding. Plenty of it!
 
I think you're going to struggle given the overall design you've envisioned. You will spend a lot of money and I'm not sure it's going to pay off. Just my opinion but you're better using a better chamber, more airflow, and a smaller displacement with higher rpm window.
 
moper said:
I think you're going to struggle given the overall design you've envisioned. /QUOTE]

Agreed.

I tossed around the idea of building a shorter stroke combo myself but when you really start to look at hp/dollar spent, the stroker really becomes a no brainer. It's so much easier to make those numbers with more cubes. Why fight physics? Frankly, it looks the same from outside, no one will know it's stroked unless you tell 'em it is.

Just to discuss your point though - any 'real' serious performance small block Mopar head is gonna be $2,500-up when you start adding up all the pieces. SB Victor heads are coming out, what are they, like $3,200? Plus, (generally) the stuff that flows a lot of air usually involves offset rocker arms. Price those out lately?

600 hp is also pretty much solid roller cam territory. Roller lifters are not cheap plus all the headaches of retro fitting them in a block that was not designed for them.

Everything is doable of course, just depends how much you want to spend as the old adage goes. 13:1 is a lot of compression, maybe you could get there with that much squeeze?

Again, the block is not your limiting factor. It's your wallet.
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There is a better factory block. The 340-1 is used by most all 358 class sprint cars . They are the first pour of the day. less porocity at the start of the ladle. tighter quality control at the start of the shift. I found like all others that the dash one blocks sonic test better.

The 340 having thinner walls because of the large bore is false. a concentric 340 can go 0.60 easily, most 360's are done at .040.

I have seen thick web blocks in late 70 a-bodies. Same as TA.block without the TA. on the block

The way to tell them easily is. The machined area above the front main . The two little machined bumps above the main cap for the bolt. One is much larger then the other. same as T/A block. or X-block.. If you look at some images you will see what I mean. also much heavier. Nickel weighs more.

If you are buying a 340 block .The lower the number after the 340 the better the block, 340 -1 being the best.

I am not saying others are not good but flex under load causes damage. a stiff block means no damage from flex. One of the reasons for the use of front and mid plates on a sprint car. No pulling on the side of the mount ears. Wonder why they moved them front on the 340?

I have a standard deck and bore 340-1 block here. with crank and rods $600. Fresh X heads and crane addjustable rockers another $600. will throw in the cam and the rest of the motor parts on the pallet. Sold valve covers and intake The rest is here with lots of new parts. 1971 340. stamped 70

I love High reving torque monsters. and I scattered many small blocks learning when they were plentiful.
 
I think its a viable package. Even if it failed to make 600 hp and say came in somewhere between 550 and 575, it would still be very fun to race. To be frank I've come to the conclusion that drag racing automatics is boring unless you can afford enough power where its difficult to even get it down the track. Ad a manual trans to make it more challenging and the fun factor goes way up.
 
Doosterfy said:
I think its a viable package. Even if it failed to make 600 hp and say came in somewhere between 550 and 575, it would still be very fun to race. To be frank I've come to the conclusion that drag racing automatics is boring unless you can afford enough power where its difficult to even get it down the track. Ad a manual trans to make it more challenging and the fun factor goes way up.
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Ha, drag racing is boring period compared to road racing/ trans am type racing. If you truly are going with a 4-speed drag car the block selection may be the least of your worries, you will need to bullit proof everything from the block back$$$. Also look into a 70-73 360 block for thick bore, only bore what is needed if you can get by with .010 or .020 great!
 
Old man mopar, I have had early 340 blocks that can't take a .040 overbore. Yep! You read right. Thin wall 340's. Would you like my junk shipped to so you can so if it yourself? I got the proof. Just sayin.
Thick walled early blocks have been proven myths next to thin walled late model blocks.

Moral of my tale, sonic check what you get and bore it out as little as possible.
 
One thing I've noticed/learned over the years (maybe others have seen this too?)

Sometime in 1970, Chrysler started using T/A 340 Blocks for Warranty Replacement Engines on 70-73 340 Cars.

I've come across more than a few over the years, where the original engine had been replaced with a Warranty/Dealer engine (No VIN on the pan rail), and each time, they were T/A Blocks.
 
hey 74 dusted, what did these warranty blocks have for a casting number? I have 1 and am very interested, so they what? removed the ta from the casting #, and how are they identified, the thicker main webs? and no stamped numbers
 
EL5DEMON340 said:
Ha, drag racing is boring period compared to road racing/ trans am type racing. If you truly are going with a 4-speed drag car the block selection may be the least of your worries, you will need to bullit proof everything from the block back$$$. Also look into a 70-73 360 block for thick bore, only bore what is needed if you can get by with .010 or .020 great!
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Well I'd love to go road racing but lets face it, road racing is for rich guys and I'm not rich. I hardly consider drag racing boring either. In fact I've loved drag racing since I first saw it on TV in the late 60s. As far as the driveline I already have a rear axle that is more than up to it. Strange nine inch with a back brace. Its good for 750 hp with a manual trans or automatic with a trans brake. I know the transmission won't be cheap, believe me. I have ran a four speed car before so I'm not coming in blind. I'm considering an A-833 from Passon or I may look for a good used Jerico.

Axle in car 2.JPG
 
EL5DEMON340 said:
Ha, drag racing is boring period compared to road racing/ trans am type racing. If you truly are going with a 4-speed drag car the block selection may be the least of your worries, you will need to bullit proof everything from the block back$$$. Also look into a 70-73 360 block for thick bore, only bore what is needed if you can get by with .010 or .020 great!
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The car also has very good frame connectors that are notched into the rear frame and floors and are 100% welded in and a five point chrome moly roll bar. The suspension is completely rebuilt and there are Wilwwod discs on all four corners. Its well suited for a small block four speed setup.

F C 9.JPG


IMAG0257.jpg
 
Sorry for the attachments, posting from my phone and have no idea what they are or where they came from.
 
Doosterfy said:
Well I'd love to go road racing but lets face it, road racing is for rich guys and I'm not rich. I hardly consider drag racing boring either. In fact I've loved drag racing since I first saw it on TV in the late 60s. As far as the driveline I already have a rear axle that is more than up to it. Strange nine inch with a back brace. Its good for 750 hp with a manual trans or automatic with a trans brake. I know the transmission won't be cheap, believe me. I have ran a four speed car before so I'm not coming in blind. I'm considering an A-833 from Passon or I may look for a good used Jerico.

View attachment 1714919894
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If you buy a junk clutch you will break parts. I realize this is an engine thread, but we are off track and I wanted to point out, once again, cheap, nonadjustable clutches break parts. No matter how good the parts are.
 
rumblefish360 said:
Old man mopar, I have had early 340 blocks that can't take a .040 overbore. .

not an early block but a first run casting on a new mould before
core revisions,specifically 340 -1,and that could be any year.
i also heard 1970 blocks had the highest nickel content and were
the best blocks,but who knows for sure?
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yellow rose said:
If you buy a junk clutch you will break parts. I realize this is an engine thread, but we are off track and I wanted to point out, once again, cheap, nonadjustable clutches break parts. No matter how good the parts are.
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The last thing in the world I would do is spend lots of money on a combo then skimp on something as critical as the clutch.
 
You'll have a bunch of fun getting it consistent, and keeping it that way. That's for sure. But it sounds like a challange is what you want so good luck with it!
 
Get together with Mike Jones in Denver NC
have the head flows for your potential heads- that's where the power is
then figure your rpm drop for your trans
Mike can figure what stroke is going to give you the most hp under your shift curve and what rpm you have to run
Is this a heads up class?
if not run as little rpm as possible cus cubic dollars goes up with rpm which is why a stroker makes sense if rules allow- you can make the heads work over a wider rpm range. if you do not need that wide an rpm range reduce the stroke but $$$/ run may go up
needless to say but you need to build a light weight rotating assembly- long rod-11/32 valves drilled if possible
lighter if heads up- longer rod, ti valves
I built several road race 340 block 305 combinations - that works with a long rod if it is a class that is lbs/ cu in or something like that
you are most likely to use a chevy rod size
 
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