I don't think the 273, 318, 340 pistons weigh the same ? So the balance would be different, or am I wrong.
340 Identification.
- Thread starter ValiantKindOfGuy
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I don't think the 273, 318, 340 pistons weigh the same ? So the balance would be different, or am I wrong.
ValiantKindOfGuy
Well-Known Member
Correct. I will pull the pan tonight and see what I have.
I think you will find you have an externally balanced cast crank 340. That balancer I don't believe is for an internally balanced engine. The balance holes are pretty deep and also about the same width and length as the scallop taken out of some of the later LA 360 engines. I know those are different, but nonetheless, I believe that's what you will find. Just no way to tell without removing the pan. Did the engine run good and smooth with no vibrations? I am betting it probably did.
Even if you decide which way you want to go with a "future project", it may be derailed until you actually tear the engine down. You will see what you have then. Block may be cracked. Ring glands melted. Crank may be beyond saving. Only can tell by inspecting it after you open it up and see what you have. Stroker kit later will open a lot of options, since its not original to any of your vehicles, hence resale value.
Just take a look inside it, and then decide. Build it your way and dont worry about being original after 40+ years. And by all means , have fun with it!
Just take a look inside it, and then decide. Build it your way and dont worry about being original after 40+ years. And by all means , have fun with it!
Balancers transfer across all internally balanced 273-318-340. The difference in balancing is taken up by crank counterweights.
It's a forged crank balancer on the engine.
It's a forged crank balancer on the engine.
That balancer is not a 340 cast crank balancer. The correct one is pictured in post #4. It says right on the front "340 cast crank only". This is the only balancer ever used on the cast crank 340.
So its either a forged crank or someone put the wrong balancer on it. Pull the pan to find out, its the only way. Some of the early 72 340's had forged crank still, maybe you got lucky.
So its either a forged crank or someone put the wrong balancer on it. Pull the pan to find out, its the only way. Some of the early 72 340's had forged crank still, maybe you got lucky.
With the block date code of '72, and the balance weight added to the torque converter.
I am going to say that it is that year specific externally balanced 340. The external balancer for the 340 has a little less weight on it than the external balancers for the 360s.
Looks like the last engine rebuilder put a neutral balance 318/340 balancer on it, maybe not knowing the difference, maybe liked the looks of it better, maybe trying to pass off the engine as a forged crank nuetral balance, when in reality it is a cast crank external balance.
Anyway if it was a neutral balance 340 crank, there should not be that extra weight on the torque converter to go with the external balanced engines. So things are miss matched there.
I am going to say that it is that year specific externally balanced 340. The external balancer for the 340 has a little less weight on it than the external balancers for the 360s.
Looks like the last engine rebuilder put a neutral balance 318/340 balancer on it, maybe not knowing the difference, maybe liked the looks of it better, maybe trying to pass off the engine as a forged crank nuetral balance, when in reality it is a cast crank external balance.
Anyway if it was a neutral balance 340 crank, there should not be that extra weight on the torque converter to go with the external balanced engines. So things are miss matched there.
There are balance weights on some neutral converters, might not be the big one a cast crank requires
pishta
I know I'm right....
the crank balance would be different but the forged crank damper would still be balanced to zero as the balancer had no crank balance influence. The dimples that you see are in every neutral balancer to balance themselves.
Wyrmrider
Well-Known Member
different sized motors pistons do not all weigh the same
Are you able to get a good reading of the vin number on the pan rail? I am looking for the original late 72 340 engine from my Demon.
ValiantKindOfGuy
Well-Known Member
It’s not for sale sorry it’s going in my Valiant. It would have to be a good price for me to let it go.
ValiantKindOfGuy
Well-Known Member
Exactly. It’s a forged crank with a neutral balancer. I’m going to say it neutral and call it at that.
ValiantKindOfGuy
Well-Known Member
Forged.
ValiantKindOfGuy
Well-Known Member
I pulled the engine apart in the last few nights. Measured everything. It’s a forged crank with std mains and Rod journals, they look good and the bearings look good. Pistons are good, ring lands are good, rings look good. It’s .030 over and bore measures true and straight with no ridge. The short block appears to be a fresh build and astonishingly well put together for the lack of correct parts when they built the car. Everything got a thorough cleaning although it didn’t really need it. The short block is now back together and awaiting new top end gaskets. A lot of 4am nights if your wondering lol. I’m gonna take the heads apart next and clean them up and check the valve job and clearances. Hard to believe I got this engine in a parts car lol. Thank you all for the help on this.
Mattmoto441
Well-Known Member
2/8/1972 looks like the build date built at 9pm night shift
I have a complete 69 and 71 340 engine i would trade, but its up to you.
ValiantKindOfGuy
Well-Known Member
where are you located? I’m not saying yes but I would consider it for a trade.
I am in Ontario Canada, in a border town with Massenna NY. Takes 5 minutes to get into the US, well before Covid-19 was here...lol
ValiantKindOfGuy
Well-Known Member
Post or on me some pics of the engines.
ok, no problem. Will do that this afternoon when I get home from work. Did you get the number from your engine?
ValiantKindOfGuy
Well-Known Member
I’ll see if I can clean it up and read it later when I get home from work.
ValiantKindOfGuy
Well-Known Member
I’ll see if I can clean it up and read it later when I get home from work.
ok, cool. Thanks.
cudamark
Well-Known Member
It sounds to me like there may be some mismatched parts on this setup. With that casting date, it probably came originally with a cast crank (externally balanced). That would also jibe with the weight on the converter. The balancer looks to be for an internally balanced engine however. Only pulling the pan will tell the story.
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