please help converter install Prob/Question

[71swing]

trying to finish up this dynamic converter install. Got the damn thing in and now trying to install the converter bolts. Had to purchase a set of mopar bolts from summit because the prev b&m converter used 5/16th and not 7/16 which the dynamic uses. Now for my question.

When I purchased the converter, shawn @ dynamic said I would need a b&m flexplate, which I said I had. I have a b&m part#BMM-10230. Which b&m states is for internally balanced engines. But now that I am trying to bolt up the converter I cant seem to get any of the bolt holes to line up.

Do I need the flexplate part#BMM-10235 which B&M states is for External balanced engines?

What is the difference between internal and externally balanced?

I just know you guys are going to tell me I have to pull it all apart again. :wack:

Here is a link to B&M website so you can see the two different flexplates.
http://www.bmracing.com/index.php?id=products&sid=4&cat=7&subcat=20&pid=218

 

[mikedevore]

The only difference between the B&M flex plates are the cut out scallop for the external balance. I have both flexplates, the bolt patterns are the same. there is one lug that is offset in all Mopar style converters, you will have to line it up. Now I have seem the tolerance of the welded on lugs to be off a few thousandths, which would make it hard to get the bolt started. I am waiting on my Dynamic converter to get here, I will check it out closely before I install the flex plate. Hope this helps.

 

[DARTLARRY]

All 318s Were Internally Balanced. So Youdont Need A Balanced Flexplate. The 360 On The Other Hand Is Externally Balanced. It Does Need A Balanced Flexplate. The B&m Piece For The 360 Looks Like A Cookie With A Bite Out Of It.

 

[ElephantKiller]

Do you have the torque converter and the flexplate lined up properly? I had the same problem with my TCI torque converter and thought they had sent me the wrong converter. There is only one way the flexplate can bolt to the torque converter. What I did was rotate the torque convter while the flexplate remained stationary until the bolt holes lined up. To help me in the future I spary painted one of the ears of the flexplate and that mounting boss of the torque converter so I would know they were a match set.

 

[mbaird]

what motor are you running? and what year is it ? The external balance B&M is round
with what looks lIkea bite out of one side . The holes are not evenly spaced so you will have to rotate it to find the correct alignment (trial and error) once you find the
correct alignment mark the flex plate and torque converter for future reference.

BTW , make sure your converter is not prebalanced if you're using the external balanced flex plate and visa versa. this will create severe vibration that will
destroy your crank and block

 

[71swing]

My combo Is 340, but the enigine is not original to the car. The car was originally a 71 swinger with a staight six. The prev. owner took it all out and put in the 340,727, and the 8-4/3 rear. When I purchased the car it was in close to stock condition. I mean a basic 340 with no real mods. I have gone through the car replacing everything I can. Bottom line is that I'm not sure the year of the engine but I did install the b&m converter I'm taking out now, and the flex plate over a year ago.

When I have purchased parts in the past I have just done it by year, as if the parts where oringinal to the car and have never had a problem.

The flexplate itself has three different holes, One set is what the prev. converter was in 5/16th and I think its for a 10" bolt pattern. Than there are holes just outside of those I believe that are for a 11" bolt pattern. Than there are a set of hole to the side of the the first set that are 7/16th. This is the set I was trying to get lined up.

On a prev thread somebody had mentioned drilling out somehole to the flexplate, but didn't pay much attention to it because the product quality that people claim to get from dynamic should not involve drilling out holes.

Maybe I'm jumping the gun on not being able to line things up, I will try again tommorrow morning. May have to make a call to dynamic if it don't work out.

My only concern is the converter that I'm taking out summit's notes say it is for use on externally balanced engines.
http://store.summitracing.com/partd...400004+4294865449+4294905607+115&autoview=sku

But the flexplate that I run is noted for internal balanced engines.
http://store.summitracing.com/partdetail.asp?part=BMM-10230&autoview=sku

But I never had any vibration problems before and I have had the converter in the car for over a year, even took it to the track a few times for some disapointing runs.

 

[mikedevore]

My combo Is 340, but the enigine is not original to the car. The car was originally a 71 swinger with a staight six. The prev. owner took it all out and put in the 340,727, and the 8-4/3 rear. When I purchased the car it was in close to stock condition. I mean a basic 340 with no real mods. I have gone through the car replacing everything I can. Bottom line is that I'm not sure the year of the engine but I did install the b&m converter I'm taking out now, and the flex plate over a year ago.

When I have purchased parts in the past I have just done it by year, as if the parts where oringinal to the car and have never had a problem.

The flexplate itself has three different holes, One set is what the prev. converter was in 5/16th and I think its for a 10" bolt pattern. Than there are holes just outside of those I believe that are for a 11" bolt pattern. Than there are a set of hole to the side of the the first set that are 7/16th. This is the set I was trying to get lined up.

On a prev thread somebody had mentioned drilling out somehole to the flexplate, but didn't pay much attention to it because the product quality that people claim to get from dynamic should not involve drilling out holes.

Maybe I'm jumping the gun on not being able to line things up, I will try again tommorrow morning. May have to make a call to dynamic if it don't work out.

My only concern is the converter that I'm taking out summit's notes say it is for use on externally balanced engines.
http://store.summitracing.com/partd...400004+4294865449+4294905607+115&autoview=sku

But the flexplate that I run is noted for internal balanced engines.
http://store.summitracing.com/partdetail.asp?part=BMM-10230&autoview=sku

But I never had any vibration problems before and I have had the converter in the car for over a year, even took it to the track a few times for some disapointing runs.

Do you know what year of 340? There is a castingfdate on the side of the block. Do you know if it is a steel crank? Does the harmonic balancer have an offset counter weight on it? does the converter have any welded on weights?

 

[71swing]

can you give me a better idea as where to look for this casting on the block.

No i do not think that the dynamic has any weights and I believe the b&M does not either.

 

[71swing]

I just got off the phone with shawn @ dynamic and he tells me all there stuff is neutral balanced so now it comes down to if I have the right flexplate.

Shawn also told me that, the majority of the 340 are internal so my chances are that. He claims that the converter should line up fine with the flex plate that I have.

Here are some pics of the b&M I took out and I don't see any weight to make it a balanced converter.

So my bet is that I'm fine with what I have and just need to be patient with the aligning of the flex/converter. If somthing wasn't balanced right over the last year I think I would have be noticed a vibration like that.

Let me know what you think. in the mean time I'm going to bed, I work nights and need to resume tommorrow thanks guys for all the help quickly.

 

[71swing]

well after a little power nap for work I played with the car a little did finally get the right combo of rotations to get the converter to line up.

I did get the castings off the sides and on the stater side it indeed says 340,
and on the other side the casting date is 11*24*68. Which I hope should be a internally balanced motor.

If I'm good on the internal balance thing all I have to do I reconnect the exhaust and add oil. Than I can see the difference between my 3800 dynamic and a B&M 2400.

Really glad this looks to be going right, because I did not want to pull it all back apart. I have change converter in both of my mustangs several times and this is the second time on the dart. There is a whole lot less room to reach those tranny bolts on the dart compared to the mustangs. The long tube headers didn't help any either.

My last concern on the car is the length of the driveshaft. I have really no slip yoke play. When I install or take out it out I have to push in on the rear seal. When the shaft is in the rear seal covers the whole yoke to the end.

What length should the drive shaft be and where to measure? u-jount to u-jount?