340-904 thrust bearing/crank issue

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Orange67Dart

Orange67Dart

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Hello to all, and thank you in advance for reading my post. I am new to this site and will do my best to describe my dilemma. I recently purchased a 67 Dart GT. It has a 340 coupled to a 904 that has been modded to reverse pattern ratchet shift and 3800 stall converter. The crank is ruined at the thrust bearing.disgust The engine is being torn down and I'm awaiting the recommendations of the machine shop as to all it will need. (so far a new crank) The transmission is the main suspect in this, it was purchased new ($1600) by the previous owner about a year and a half ago. My question is did he do something wrong with the install and what should I do to avoid having this happen again? :sad11:
 
have the converter checked to see if it balloon .......if so it will push the crank forward ruining the thrust bearing..
 
70aarcuda said:
have the converter checked to see if it balloon .......if so it will push the crank forward ruining the thrust bearing..
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Yup, that's the most likely cause. I've had good luck having the crank thrust surface welded back up to specs so you might want to check into that option. If you don't EVER want to have it happen to you again, you could give me the car! :) Otherwise, you cranks it up, you takes your chances.......
 
Thank you all for the answers. I assumed the converter was most likeley the issue. By the way cudamark, I would have the crank welded, but it's really gouged out badly. luckily the block looks to be okay with some minor rubbing at the front bearing. I'll have more peace of mind going with a new crank though. I just have to wait for my engine builder to let me know what one to get, as well as what other parts it will need. Too bad about the converter as I guess it's junk now too. I have a receipt for it, the previous owner paid $520 for it. Any suggestions for a reliable replacement?:burnout:
 
I had one with so much end play that the converter bolts were clipping the back of the block and they were still able to weld it up and machine it to specs. I think I would take some measurements on your converter and compare it to a stock one to see if it has actually ballooned or not. It may have been a bad crank grind on a previous rebuild.
 
Once again thank you all for the advice. I'll wait for the findings of the machine shop and proceed with the rebuild/repair of the 340 from there. It's hard to believe, but the thing actually ran pretty good even with the damage. I was checking the timing when I noticed the balancer moving back and forth. I'm thinking things could have ended up much worse. This site is terriffic and I'll be spending alot of what little free time I have consulting with all of you!:thumrigh:
 
Wow! I just looked through the gallery and discovered I now own Beatnik's car!!! She's a long way from Colorado!
 
It is also very possible that the crank grinder "banged" the thrust making it too loose on the previous build, and got gradually worse.
I normally try to use the larger flanged thrust bearing (there are 2 diff flange sizes) and file a small "channel" on the end of the bearing where the halves meet, from the groove to the rear thrust surface, just for a little more oil.
If the convertor didnt have balloon plates and got hit with a healthy shot of n2o that will deff do it to.
You may want a convertor shop to inspect it. They swell when they get too much power for their rating, then shrink back down when they cool off. Can be hard for an untrained eye to determine if there is a prob.
 
Thanks 66V100. It's going to get a new forged crank, as well as whatever else will be needed. I'll look into having the converter tested but would feel better buying a new one. I really don't think it was ever nos'd. Like I said it ran okay and had 75lbs of oil press. I just didn't see the crank movement untill after I owned it for a week. I'm probably lucky it didn't go grenade style on me. The shop that has it now is one of the best around here. I'm no engine builder, but I sure am learning a whole lot of new things since I bought this little screamer! I'll mention what you said when they call me with the results of the tear down.
 
Orange67Dart said:
Wow! I just looked through the gallery and discovered I now own Beatnik's car!!! She's a long way from Colorado!
Click to expand...

Yes you do! Man..sight for sore eyes. I miss that car SO much! Kinda glad I'll be able to follow it again here on FABO! I actually called Dan in NY about a week after you bought it to ask the status of it...ironic
 
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