Picking Up 340 Short Block - What to Look For?

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Swinger Ron

Father/Son - 1970 Dodge Swinger
Joined
Nov 5, 2018
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Location
Ottawa, Ontario, Canada
Hi All,
We came across a great deal we felt we should jump on. It is a 340 short block standard bore. The current installed engine in are 1970 Dart Swinger is a 340 bored 60 over and we worry it is just a matter of time before it gives out. But it has all the goodies on it.
For those who know the numbers here they are:
2780930-340-3
7*11*69
0B21294

I read the witchcraft numbers to mean the third casting from the mold. original casting made in 1969. 0 to mean a 1970 vehicle it came from followed by some of the vin numbers.
See the uploaded photos. I would appreciate any and all comments. The seller is going to measure on the spot the boring numbers with proper tools.


as advertised: "1969 / 1970 dodge block 340 cleaned and magnefluxed date 7 / 69 stn bore"

$678 us dollars.

Casting.jpeg


Casting2.jpeg


crank.jpeg


vin.jpeg
 
It would be cool to see a close up of the VIN stamp, I can see what looks like a very poorly stamped number between the 2 & 9, but not enough to know for sure.
 
The -3 is the mold revision number, it means the mold was on its 3rd revision to correct core shift, etc. from multiple use.
 
not to hijack the thread, but it seems like i see more 68 model year 340s with casting dates of mid summer 67,,i know the 67 casting was correct for 68, but any idea why so many,,(seems like most every) 67 340 castings are all within 2 or 3 weeks time period on june/july?
 
With the 'new' for '68 engine approaching for the 1968 model year, they needed to have inventory available.
 
not to hijack the thread, but it seems like i see more 68 model year 340s with casting dates of mid summer 67,,i know the 67 casting was correct for 68, but any idea why so many,,(seems like most every) 67 340 castings are all within 2 or 3 weeks time period on june/july?
Likely to satisfy early dealer orders for the new model year.

Often the dealers had to get hot selling models scheduled for production early in the model year. Better to have them on the lot to sell...people buy with their eyes and those young buyers would buy on the spot if they saw what they wanted.
 
Hi All,
We came across a great deal we felt we should jump on. It is a 340 short block standard bore. The current installed engine in are 1970 Dart Swinger is a 340 bored 60 over and we worry it is just a matter of time before it gives out. But it has all the goodies on it.
For those who know the numbers here they are:
2780930-340-3
7*11*69
0B21294

I read the witchcraft numbers to mean the third casting from the mold. original casting made in 1969. 0 to mean a 1970 vehicle it came from followed by some of the vin numbers.
See the uploaded photos. I would appreciate any and all comments. The seller is going to measure on the spot the boring numbers with proper tools.


as advertised: "1969 / 1970 dodge block 340 cleaned and magnefluxed date 7 / 69 stn bore"

$678 us dollars.

View attachment 1715396729

View attachment 1715396730

View attachment 1715396731

View attachment 1715396732
 
.060 is fine and can likely go .100 over. Sonic test it to be sure.

Oh and I would be lookin for help to pick one up.
 
Hi All,
I am still looking to get more comments I can take with me to evaluate the condition of the block. Truth is I am driving 5 hours to pick it up, unless there is a crack down the middle it’s coming home. Can someone maybe give me its value $$ as it sits as a clean short block?
Thanks
 
I don't see a short block. All I see is a bare block. Hard to put a value on something I caint see. Is it a steel crank? Standard or? What rods? Floating or pressed pins? Cast or forged crank? I know what the numbers say it should be but that's useless as tits on a boarhog as old as it is.
 
I agree with RRR,

Is the block all your getting?
Are the main caps original or changed.
Bore sizes proper for what they are selling you.
No cracks. Chase the threads by the timing chain cover. Or chase all the threads.
Bring a straight edge and feeler gauges and check head mounting surfaces.

Honestly there are a lot you can look for before you buy but it is a 50 year old part.
Risk vs reward.
Good luck and enjoy the road trip!
 
Bores look awful clean for a used standard bore block. Maybe they've been honed. I'd be looking for a ridge at the top of the cylinders. Take a caliper to at least get a rough measurement of the bore and main bearing bores. If it is a standard bore and there aren't any cracks the price seems fair. I've seen a lot uglier ones go for $1000+. Used cranks should be available with all the stroker kits going in, so that wouldn't deter me.
 
I used the term short block. Sorry it is just the block and caps.
Thanks
Ron


Without some measuring tools, you'll be hard pressed to do more than give it the stink eye and see what you see.

At least a pair of calipers would help. You can measure the top of the bore and see where it's at. And torque the main caps and see what you see.

If you have a 4-5 inch micrometer and snap gauges and are careful you can verify the bores down the hole and get a little better idea of the main bore sizes.

Now, if you have a dial bore gauge you'd be pooping in tall cotton.

Look for bad threads and bolts broken off in the holes. They can be a PITA for sure.

Look at the main bearing saddles and look for cracks there. You can't really see cracks without a mag, but sometimes you can see them in that area.

Just ASSume you'll need to bore it (again, unless you have a bore gauge) line hone it (I line hone everything) and deck it.

Price accordingly.
 
$678US is a bit high for a good 340 block & caps. )But I've seen rusty pieces of junk for a $500 asking price!) What you can find that is decent is a factor since you need a specific block. We shopped around and got lucky and got a .005" over 340 block in good shape for $300... not likely to ever find that again, but I'd expect to find something pretty good for $500.

Standard bore is good to have! You can get .020" over pistons and save the block for a coupla more overbores. But verify.... supposedly being stock bore has value.

No way to know of it is cracked or not if not properly tested. Any info or guarantees being provided?

Any chance this is coming our of the NW Ohio area?
 
not to hijack the thread, but it seems like i see more 68 model year 340s with casting dates of mid summer 67,,i know the 67 casting was correct for 68, but any idea why so many,,(seems like most every) 67 340 castings are all within 2 or 3 weeks time period on june/july?


With the 'new' for '68 engine approaching for the 1968 model year, they needed to have inventory available.


They also needed to run some blocks off the production tooling to evaluate the quality of the tool... Plus if you are going to set up and run the tool, then you may as well run a large batch once you determine that the parts are within sped...

Not to mention that they have to have enough castings available to set up and verify the block machining line... They need to run many blocks through each operation on the block machine line to measure and take data to see where the machining is and to make adjustments to the machining... Since the 340 was brand new for 68, they would have to run a minimum of 30 blocks through every station of the block machine line to measure the parts with the gauges and certify each operation and certify every gauge... You have to run them down the machine line one operation/station at a time from beginning to end... This takes time to do each step along the way...

Plus you need to run some extra blocks through the front of the machine line to make sure you have enough to redo any of the stations further down the line in case you find any out of spec or need to make an adjustment to the machining... After each adjustment you need to run a minimum of 30 parts through the station to get a good idea of where that operation is running in relation to the tolerance spec... Sometimes you target the nominal (middle of the tolerance spec) and sometimes you set them up to one side or the other of the spec to allow for it to wear towards the middle of the spec as the tool wears...


Then you need to machine a bunch of blocks to have for setting up the engine assembly line... You have to back fill an empty line and run them through each station to test the tooling on the engine assembly line...

Then the assembly plant needs enough parts/engines to run their pilot builds... They have a pilot build 6 weeks before production launch (called the PVP build - Pre-Volume Production) to test and verify that all of the tools on the assembly line are capable and ready for production... This is typically 100 - 150 vehicles that are built before production begins... Many of those vehicles are sent to engineering to start running their production verification testing... Every department needs some of the pilot vehicles to verify that their parts are meeting design specs... Engine group, climate control group, engine cooling group, interior group, exterior body group, chassis group, transmission group, vehicle development group, and some are sent to the proving grounds to get miles on them to make sure that there are no problems... They would send some to the Chelsea, MI proving grounds, and some to the Phoenix, AZ proving grounds to start accumulating as many miles as possible before launch to identify if there any problems...

If any problems are found during that testing, then they will hold that particular part of the launch until the design group can identify the problem, come up with a fix, test that the fix will work, and then get the tooling changed to implement that fix... If the production tooling cannot be modified in time, then they may be able to write a temporary deviation (TSA) to launch with a prototype tool until the production tool can be modified and proven for production... Prototype tooling is called "soft tooling" as it is made to run a limited amount of parts before it wears vs the production tool also called "hard tooling" which is harder and made to run many parts over a longer period of time before wearing out... Production tooling is much more durable and made to run more parts over a longer period of time...

PVP builds are supposed to be run of production tooling... If the production tooling is not available then that particular part has to have a deviation written (TSA) and then put on a "hot list" to allow them to run PVP pilot builds off prototype tools...

If they can get a successful PVP pilot run (6 weeks before production launch) they will run a batch of engines to have a bank built up for the assembly plant PVP pilot run and then the production launch... That way the engine plant has completed their launch and the parts will be ready and available for the assembly plant launch... It's better to build them early than to wait until the last minute and have to jump through hoops if a problem arises that could potentially delay the launch...


So that is why you see so many June & July 67 casting blocks as when the foundry has the molds ready, they made a batch run of blocks to run the pilot and launch builds for the engine assembly and vehicle assembly plants... That way they can run a few large batch runs of blocks instead of running smaller batch runs and having to set up the casting line so many times... If you have to do the change over, then run as many as possible to save time later... Then the engine plant can build a bank of engines and have a bank of them ready for the assembly plant launch and start of production...
 
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Likely to satisfy early dealer orders for the new model year.

Often the dealers had to get hot selling models scheduled for production early in the model year. Better to have them on the lot to sell...people buy with their eyes and those young buyers would buy on the spot if they saw what they wanted.


They usually hold the first production vehicles for a month until all of the verification testing is done... That way they can fix them at the assembly plant vs having to recall them if any problems are found...

Plus they can fix them better at the assembly plant than the dealer can because the assembly plant workers are more familiar with them than the mechanics in the field... The UAW workers learn them during the pilot builds and become more familiar with them and can do a better quality repair than the mechanics who are seeing them for the first time...

In addition, the design engineer and plant engineer will be there along side of them when they first start repairing them with the new fix to show them how it's supposed to go together and the repairs are done correctly... This will also eliminate the need to write a TSB (Technical Service Bulletin) for the mechanics to fix in the field... It keeps everything cleaner and all in house...
 
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wow,,i love learning all this stuff,,,thanks so much for the details and inside scoop! loved it!!!!
 
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