73 340 RR Back to life

MoparJimT said:

I found it out of a company in Oregon. Took 6 month to get it even before covid, I think they had to make the material or something. I almost gave up. They did communicate well. PM me and I can help you find them.

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Mine is in good shape.

I was just curious as I've never seen that style listed for sale.

I was able to get back down to AZ to get some more work done.

Got the front moulding on and finished the interior trim.

Got the doors on and adjusted. Thanks to Builderguy, installing the door bumpers before you close the doors was a great tip! Definitely saved the paint.


Finishing the accessories for the engine compartment. Getting close to adding fluids and a battery then firing it up.



I am struggling with the window regulators, they are really binding and won't move up or down. I ran out of time this trip. Could use any tips and tricks, I am also thinking they may just be plain wornout. I cannot find a rebuild kit for a 1973. Will other years work? Thank in advance!

This looks GREAT!!! Very nice work. Quick question, the rubber drip rail seal, did you glue that in. Looks like mine has some glue residue over the entire channel. There was also some chatter about using a little glue around the plastic body darts on the front edge (I think there are 3 darts) to relieve some of the stress on the darts.

Builderguy said:

This looks GREAT!!! Very nice work. Quick question, the rubber drip rail seal, did you glue that in. Looks like mine has some glue residue over the entire channel. There was also some chatter about using a little glue around the plastic body darts on the front edge (I think there are 3 darts) to relieve some of the stress on the darts.

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I did not use any glue on mine. There wasn't any when I took mine apart and the body manual did not call for it. Glue around the darts maybe a good idea though I did not use an did not think of it at the time.
I did read in the body manual to put glue in between the clips on the door seal that goes down the front of the door across the bottom and up to the door end cap.
Any thoughts or pics on the regulator. Maybe I got something mixed up between pass and driver side. It was a long time ago when I took them out and my pics are not helping

If I haven't said it already, I love that color combo.

Do the windows go up and down freely in the channels without the regulators?

Do the regulators wind freely without being attached to the windows?

YY1 said:

If I haven't said it already, I love that color combo.

Do the windows go up and down freely in the channels without the regulators?

Do the regulators wind freely without being attached to the windows?

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I did not try the windows in the channel yet.
The regulator binds up after about 2 inches from the bottom going up. I try to help it move up but it just gets jammed. Tried loosening the bolts in different combos, top loose bottom tight vice versa all loose all tight. Also 2 of the round guides on the top horizontal rail broke off so I replaced them with the square style.

So I have good news and bad for this last trip to work on the car. I was able to get the window regulators, windows and latch assemblies installed and working. I decided to start from scratch on the driver's side since I was having no success with the passenger side. Got it installed and working in one shot. I duplicated the sequence on the passenger side with success
I had removed the rear window after reinstalling it last trip because the moulding would not fit correctly I thought the window was too high in the channel. Once we reinstalled it and immediately installed the moulding everything fit properly.

Before
After


Now for the bad news,
Next was firing up the motor. So I added all the fluids and primed the oiling system, fogged the pistons and rotated the motor by hand to spread the lube around. Set #1 cylinder to TDC on the fire stroke set the distributor in, installed the plugs and plug wires then off to the races. The engine fired but was making a binding sound, just sounded really tight. I shut it down and started looking. Found the vibration dampener was touching the timing cover which was odd, when I installed it it slid right on and was able to thread the bolt and torque it down. Also found the inspection cover was rubbing the flex plate so I removed it for now. It had some dents and dings but also found I had been over zealous with the sealant on the corners of the rear main so it oozed out and solidified. When I installed the inspection cover it was being forced against the flex plate. I will replace it and trim out the excess sealant.
I fired it up and no more noise and continued with the break in process. Once I hit the 20- 25 min mark I backed the rpms down but noticed a vibration that was too familiar. Back in the 80`s when I built the hot rod version I did not send the vibration dampener or flex plate to the machine shop so when I fired it it had a very similar vibration. Lesson was learned so I sent the vibration dampener, torque converter to the machine shop and they supplied the flex plate. I had replaced the old TRW 750 gram pistons with new RaceTech 425 gram pistons. They were supposed to balance the rotating assembly. I also made sure they understood it was an externally balanced motor which they were fully aware so they had experience and were 30 year veterans of building HP motors. So with the vibration I feel at 1000 rpm up the range I think I have another balancing issue.

HELP NEEDED DESPERATELY, any input, advice solution additional testing I should do would be very much appreciated.



It looks good I am hoping I do not have to yank the motor again. But realize I may have to. Calling the machine shop tomorrow to see what help they can provide and confirm what they did.
Some question for the group
1. If they internally balanced it by mistake can I change out the vibration dampener, flex plate and TQ to neutral balanced units?
2. I did not replace the VD, the machine shop said it looked fine, could it be too old and brittle.
3. Flex plate was a used unit the shop supplied, mine had a crack in it. Should I try replacing it with a new one instead.

Thanks Again

Thats going to be a tough one. I think the only way to 100% take care of the issue, with the least amount of swearing/thrown wrenches/alcohol abuse etc is to yank it out and redo.

Beautiful runner! My first Mopar was a 340 4 speed car. Had some good times with the blonde I was dating in that car.

That sucks!
The only thing I can think of is that the flex plate they supplied is not for an externally balanced engine. By mistake/oversight they might have given you a neutral balanced one.

MoparJimT said:

Some question for the group
1. If they internally balanced it by mistake can I change out the vibration dampener, flex plate and TQ to neutral balanced units?
2. I did not replace the VD, the machine shop said it looked fine, could it be too old and brittle.
3. Flex plate was a used unit the shop supplied, mine had a crack in it. Should I try replacing it with a new one instead.

Thanks Again

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First of all, my 1973 340 had the weights on the torque converter. If you weight the flex plate, then the torque converter weights need to be removed. Only one should have weights on it. Maybe check that first.

Answer to #1: If they internally balanced it, then yes you could replace the vibration dampener, flex plate and torque converter (if it has a weight on it) to a neutral balanced ones and you'd be fine. I doubt this, because neutrally balancing that assembly requires adding Mallory metal to the counterweights. It's not typically done for a street engine, but anything is possible.

Answer to #2: Sure this is possible, but they don't go bad often. It's possible but not likely.

Answer to #3: A used vs a new flex plate will not solve your vibration issue.

I agree with your plan to talk to the shop that built it. You need to understand how they balanced the reciprocating assembly. Something is not right.

Let us know what you find out.

Basket case said:

Beautiful runner! My first Mopar was a 340 4 speed car. Had some good times with the blonde I was dating in that car.View attachment 1130637

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Thanks it has been an adventure hopefully I can get past this current hurdle. Went on my first date with my wife 38 years ago

hsorman said:

First of all, my 1973 340 had the weights on the torque converter. If you weight the flex plate, then the torque converter weights need to be removed. Only one should have weights on it. Maybe check that first.

Answer to #1: If they internally balanced it, then yes you could replace the vibration dampener, flex plate and torque converter (if it has a weight on it) to a neutral balanced ones and you'd be fine. I doubt this, because neutrally balancing that assembly requires adding Mallory metal to the counterweights. It's not typically done for a street engine, but anything is possible.

Answer to #2: Sure this is possible, but they don't go bad often. It's possible but not likely.

Answer to #3: A used vs a new flex plate will not solve your vibration issue.

I agree with your plan to talk to the shop that built it. You need to understand how they balanced the reciprocating assembly. Something is not right.

Let us know what you find out.

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Thanks Builderguy and Hsorman,
The flex plate did not have any weights on it the torque converter does.
I will see what the machine shop has to say. I have a lot of confidence in this shop they have a good reputation and seemed very knowledgable. I will keep everyone posted.
Thank Again

MoparJimT said:

Thanks Builderguy and Hsorman,
The flex plate did not have any weights on it the torque converter does.
I will see what the machine shop has to say. I have a lot of confidence in this shop they have a good reputation and seemed very knowledgable. I will keep everyone posted.
Thank Again

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Good Luck - hopefully there is an easy answer!

Builderguy said:

This looks GREAT!!! Very nice work. Quick question, the rubber drip rail seal, did you glue that in. Looks like mine has some glue residue over the entire channel. There was also some chatter about using a little glue around the plastic body darts on the front edge (I think there are 3 darts) to relieve some of the stress on the darts.

Click to expand...

Hey Mr. Builderguy, just a quick follow up on your question. While adjusting the windows I noticed the drip rail seal kept coming loose so I did end up glueing it in a few spots.

MoparJimT said:

Thanks Builderguy and Hsorman,
The flex plate did not have any weights on it the torque converter does.
I will see what the machine shop has to say. I have a lot of confidence in this shop they have a good reputation and seemed very knowledgable. I will keep everyone posted.
Thank Again

Click to expand...

So I spoke to the shop and we went through what they did and the balance records he took. It does sound like he weighed each piston, rings, rods both ends, then balanced with the harmonic balancer, flex plate and torque converter.

Here is the one thing that threw me off, he suggested we try replacing th HB and TC with neutral balanced units. I thought neutral meant no weights so I asked and he said neutral is in reference to the balanced assembly and he made it so if the HB or TC ever needed to be replaced I would just order the stock replacements which are weighted making the assembly neutral. Is the confusing or is it just me?
I am having him order the parts but there seems to be back order issues.

A troubleshooting question I have is if I disconnected the TC from the flex plate,
1. Is there enough room to start the motor without it hitting
2. If I do this in my mind that would tell me if I need to remove the TC weights because they balanced it wrong.
3. Completely bad idea

Thanks

Just so we are on the same page, your 1973 340 should have came from the factory with this HB (which is for the cast crank).



Next, your torque converter should have came from the factory with weights attached as the cast crank requires this. You can use , or so I have read, a neutral balance converter (no weight) with a cast crank motor if you get the correct flex plate from (say) B&M racing. A lot of converters now have no weight, Chrysler sells the weight and a template so you can weld it on yourself.

I guess I am not understanding what the shop did. If they balanced everything, as written, there should not be an issue.

Since there is an issue, something is not compatible. Not quite sure but I will keep thinking about it.

As for your questions, I have never tried that, and would be hesitant to do that; but that being said, I would defer to those with more knowledge on this.

MoparJimT said:

So I spoke to the shop and we went through what they did and the balance records he took. It does sound like he weighed each piston, rings, rods both ends, then balanced with the harmonic balancer, flex plate and torque converter.

Click to expand...

This makes sense to me to use the components needed for the external balance while balancing the reciprocating assembly. I just balanced my 73 340 (stroker). It is also externally balanced so I did the balancing with my Harmonic Balancer (HB) and Flex Plate.
HOWEVER, was the Torque Converter (TC) new and empty? Just a few ounces of fluid in it could screw up the balance. My car is an automatic also but I used a weighted flex plate instead of trying to hassle with a weighted TC.

MoparJimT said:

Here is the one thing that threw me off, he suggested we try replacing th HB and TC with neutral balanced units. I thought neutral meant no weights so I asked and he said neutral is in reference to the balanced assembly and he made it so if the HB or TC ever needed to be replaced I would just order the stock replacements which are weighted making the assembly neutral. Is the confusing or is it just me?
I am having him order the parts but there seems to be back order issues.

Click to expand...

It sounds like a confusing way for him to express himself. Based on what you said it sounds like he balanced the assembly using stock external balance components you could replace them with stock external balance components in the future. That makes sense that he would balance the engine that way. As far as why he is requesting you replace your HB and TC? Did he balance the engine with YOUR HB and TC or with HIS HB and TC? If with his, that could be why he is recommending you replace them (maybe he is assuming yours are bad).

MoparJimT said:

A troubleshooting question I have is if I disconnected the TC from the flex plate,
1. Is there enough room to start the motor without it hitting
2. If I do this in my mind that would tell me if I need to remove the TC weights because they balanced it wrong.
3. Completely bad idea

Thanks

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Maybe others have done this but I woudn't want to. After disconnecting the TC you can slide it back a 1/2" or so, but I wouldn't want to trust that it stays there. if it rattles or moves forward then that could be trouble. But, if the flex plate is not weighted, then you could fully remove it. I've never done this but I would think it would work to try that. Maybe others can chime in and offer their suggestions as well.

Builderguy said:

Just so we are on the same page, your 1973 340 should have came from the factory with this HB (which is for the cast crank).

View attachment 1131323

Next, your torque converter should have came from the factory with weights attached as the cast crank requires this. You can use , or so I have read, a neutral balance converter (no weight) with a cast crank motor if you get the correct flex plate from (say) B&M racing. A lot of converters now have no weight, Chrysler sells the weight and a template so you can weld it on yourself.

I guess I am not understanding what the shop did. If they balanced everything, as written, there should not be an issue.

Since there is an issue, something is not compatible. Not quite sure but I will keep thinking about it.

As for your questions, I have never tried that, and would be hesitant to do that; but that being said, I would defer to those with more knowledge on this.

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My HB looks the same as your pic, the TC does have weights on it. I agree it sounds like he did everything correctly, mind you I am going by what he said was done, it is certainly possible someone made a mistake. Thx

hsorman said:

This makes sense to me to use the components needed for the external balance while balancing the reciprocating assembly. I just balanced my 73 340 (stroker). It is also externally balanced so I did the balancing with my Harmonic Balancer (HB) and Flex Plate.
HOWEVER, was the Torque Converter (TC) new and empty? Just a few ounces of fluid in it could screw up the balance. My car is an automatic also but I used a weighted flex plate instead of trying to hassle with a weighted TC.


It sounds like a confusing way for him to express himself. Based on what you said it sounds like he balanced the assembly using stock external balance components you could replace them with stock external balance components in the future. That makes sense that he would balance the engine that way. As far as why he is requesting you replace your HB and TC? Did he balance the engine with YOUR HB and TC or with HIS HB and TC? If with his, that could be why he is recommending you replace them (maybe he is assuming yours are bad).


Maybe others have done this but I woudn't want to. After disconnecting the TC you can slide it back a 1/2" or so, but I wouldn't want to trust that it stays there. if it rattles or moves forward then that could be trouble. But, if the flex plate is not weighted, then you could fully remove it. I've never done this but I would think it would work to try that. Maybe others can chime in and offer their suggestions as well.

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He did use all my parts except he supplied the flex plate which is the one I installed, it was a used factory unit. The TQ was new and empty as far a I know, it was supplied by the trans shop the rebuilt my trans. Thx

I appreciate you and Builderguy providing your thoughts I will keep digging.