What is inside my 340?

[MObarracuda]

FWIW... Balancers will fit either forged or cast cranks. Not that it is correct but their is a possibility a crank will have the wrong dampener.

Thanks!!

 

[Bodyperson]

Another thing about LA cranks that I've never seen mentioned on this web site is that forged 340 cranks have counter-bored rod journals to offset the weight of the beefier 340 rods.

 

[AJ/FormS]

Beefy rods?
I'm pretty sure all those LA engines from about the 1970s on, had the same castings.
Just the 273s and early teeners had the lightweights.
But I get the holey journals part.

 

[Bodyperson]

Beefy rods?
I'm pretty sure all those LA engines from about the 1970s on, had the same castings.
Just the 273s and early teeners had the lightweights.
But I get the holey journals part.

Agreed. Just saying watch your mixing and matching. I don't know much about balancing but I've always wondered what would happen

 

[71DodgeDemon340]

Agreed. Just saying watch your mixing and matching. I don't know much about balancing but I've always wondered what would happen

I sure as hell dont want to find out lol

 

[MOPAROFFICIAL]

I was thinking $2000-$2500 if all checks out.

Some people here will brag about how bad *** a good running 340 is but then won't pay what its worth...because they are cheap skates and tire kickers.
Sometimes I cannot stand mopar people...if these people were selling it, I'm sure they'd ask for more than grand...
It has a transmission, starter, so do a comp test...even cold you can see how far apart the numbers are to make a decent decision wether or not its worth it.

 

[71DodgeDemon340]

just calling like i see it. If it had documents to back up that its good to go then no problem. If it was stored properly then no problem. Why piss a extra grand away if there is a risk that there is a issue internally

 

[diymirage]

New motors aren't cheep either. $5 for a built 360 on the low side and $6K for stoked on the high side.

I dropped a 360 off at MRL and picked up a 408 a month and 4 grand later
Now, this isn't his most exciting build, but at 420 hp and 470 foot pounds, I'm happy
(But that was with my own core)

 

[JBurch]

Before I purchase a used 340 motor can anyone on FABO can tell me what cylinder heads, intake valve size, compression pistons, and crank composition (forged or cast) are inside this motor based on the serial number (2780930-340-1) and date code (10-1-71) if it is still a stock set up.

Am I a lucky boy and I have found the last 10.26:1 compression performance engine with J heads & 2.02 intake valves to come off the line or am I looking at the detuned 240hp low compression, small valve engine sold in 1972 with the October '71 date code.

Allpar.com states the cast crank started with serial number #39118000 but that is one digit longer than the one on the side of the block.

I can fix the valves if they are the 1.92" valves but the most important question to me are which compression pistons were put in it if this motor is still stock.

Thanks in advance.

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My 2 cents..........an alternate view..........

Cast crank......forged crank.....WHO CARES!!!!!! If it's a cast crank and you have your heart set on a forged crank, walk away.....in your mind it's junk, scrap metal, damaged goods, not worthy of resting under the hood of your car because it's a cast crank 340.

To know whats inside........make a deal with the shop that has it, you'll buy valve cover gaskets, an oil pan gasket and pay an agreeded labor fee if they open it up that far for your inspection, pull a main cap and a rod cap.......fair to them and fair to you. They may even have a bore scope, you could pull the spark plugs and have a look inside.

Again...........an alternate view

 

[WEBBY]

I am surprised nobody mentioned the casting numbers being 340-1, these blocks are suppose to have less core shift, the numbers go all the way up to 340-8 I believe. I would want to see the head off and the oil pan off. Just my opinion Webby.

 

[MObarracuda]

This is why I love FABO. I wanted opinions from a diverse group. I got advise from those who may be risk advers and would want the motor at a price that limits their exposure to risk. I received advise from members with practical experience who have more knowledge than me and I received fatherly advise. I even received advise from folks that went a different route and I was able to weigh these alternatives (thanks diymarige). I even enjoyed the smack talking that happened in the middle of the night.

My car is my hobbie and I love the tinkering, the grease, the history and the performance. My project will never be done and I will most likely spend 1.5x what the vehicle is worth. But when all is said and done it is about the experience. Thank you all for your comments and tech tidbits and advise. I don't want to close the thread so keep the comments coming but I wanted to thank everyone for your time and the love of this stuff.

I have an appointment to look at the motor next week and I'm bringing gaskets and tools to see what is inside. I will leave the shop with a motor or the seller back in his original position (Thanks jburch)

Thanks again and have a Merry Christmas.

 

[diymirage]

sounds like a plan
i really like the idea of not going in blind and not setting the seller back anything if you decide to pass on it

looking forward to see how this pans out

My project will never be done and I will most likely spend 1.5x what the vehicle is worth. But when all is said and done it is about the experience. .

and if all you spend is 1.5 times what the car is worth your not doing enough to/with it

 

[moper]

Sounds like a good plan. Merry Christmas!

 

[MObarracuda]

Here is my final entry on this thread. I inspected the motor last week and completed a leak down test that showed the #5 and #8 pistons were 30-40% below all the others. This could have been the cylinders that were open the 2 years the motor sat on the shelf and developed surface rust on the valves. I completed a compression test both wet and dry and tested 3 cylinders and stopped after getting readings from 95 to 110dry and 100 to 120 wet. The motor, based on my observations, seemed closer to the end of its life not the beginning. We could not come to terms on a price. The owner of the St. Louis MO based speed shop feels there will be someone who will pay $2500 just because it is a 340 with tranny. Thank you for all of your input.