pro-tech

I have a question that I am just wanting some input on... My engine in my 72 Duster was a 318 when I went to freashen it up it was cracked.. So I call a local salvage yard and they had a 360 out of a 78 D100 so the price was right so I bought it... When they delivered it, It was clean and nicely painted gray, Upon further inspection I found a Jasper rebuild lead plug in a couple of frost plugs... So I took the pan off and found the engine was all new inside.. I did my upgrades.. New pan (for car) Cam, lifters, DR timing chain and gears, intake, smog holes, etc.. I called jasper and they gave me the rest of the info by the serial number... 9.5:1 hyper pistons, bored .030" over, Etc. But that was all they could give me.. I called the salvage yard and asked them about why the engine was so new.. They told me the guy had the engine replaced and on his way home he wrecked the truck (totaled) with less then 20 miles on the engine so they got it.. He was drunk, And A win for me.. Now here is my question (finally) I installed it in my car and been driving it. It doesn't seem to vibrate . But there is no weight on the converter and the transmission shop that is building the converter for me asked if it was internally balanced??? And I don't know.. If it has a 318 harmonic balancer on it would it be balanced or not.. I don't remember switching anything off the 360 but yet it doesn't shake or vibrate when it is running and I have had it up to 5500 rpms (on the road) last year and nothing.. I don't believe Jasper balances the rotating Assemblies.. But I don't know and either does the guy that I talked to at Jasper.. Any help would be appreciated...Bill

RacerHog

Go off the old convertor.... If it had weights or not.....

pro-tech

I was going to call you but didn't want to bother you.. I was kind of thinking that too and told him to leave the weights off...Bill

RacerHog

What I found with Ma Mopars 360's is that you sometimes just dont know where there at.....

One time I has what I thought was two of the same type of 360 engines... I took out my motor and put in a motor from a wreck and the dam thing almost knocked all my filling out of all my teeth.... I wound up having to take the motor back apart to find out what the crank casting number was in the motor, Just to find out that It had a Ex. Balanced crank.....
Still I did not know what converter to install.... There was 3 different weighted converters... Of course I had the odd one in the end. I had to send the whole rotating asm out to be checked, the "The Converter Shop" I deal with had all three shells we could use to figure out what we needed...
What a mess that turned out to be...

Now... You want to know the whole kicker abut the whole thing... I got a trans with that engine..... When I sent the trans to my at the time trans dude. He turned in the converter and got the wrong one back, Yep it had the wrong weights.... Talk about a cluster mess for a few years !!!!!!!

RacerHog

Bill.... You can call me anytime.....

440roadrunner

The thing is, if this is just your average "shop" / exchange rebuild, it is absolutely guaranteed NOT be internally balanced if it's a 360, and should have either a weighted converter, or a BM weighted flex plate, plus the proper 360 balancer.

Vibration happens only at certain RPM points. You should be able to "ease" the RPM off idle and watch the engine, and see and feel the vibration at a few different RPM points.

Years before we had the internet, I put a 360 in front of a 340 flywheel and there was no doubt that it vibrated. That didn't stop me from running it, LOL. It sometimes saw 5K

If this was some sort of "rod shop" build it's possible that the internals were balanced but I'd say the odds are against this. Couldn't this engine shop tell you if they sometimes internally balance 360s? This is a rather expensive procedure, otherwise the factory!!! would have done so!!

Are you absolutely CERTAIN this is a 360? Checked the casting no's on the side of the block?

TVLynn

When I had my 360 balanced It went with the whole shebang crank,pistons, Flywheel/ B&M flex plate, SFI dampner everything..

pro-tech

Bob, Thanks for the info and the open to call anytime... my good friend....


440, Thanks you for the info... yes it is a 360 .030 over... I don't remember what crank its got whether cast or forged.. I don't know if it has been balanced by the harmonic balancer/ external or not and talking to Jasper is like talking to a phone guy that is there just to be a yes man... He just would say anything you wanted to hear and has no clue about any thing but what is on his print out... The converter shop was going to weld the weight on and if it vibrated I could just knock it off.. But with my luck it would rip a hole in the converter, so I told them to leave it off... Is there a way to cross the numbers on the balancer to see if it is from a 318 or 340 and is balancing the engine.... I am getting a headache from this mess... Bill


TV, The problem is I cant get the info from Jasper of there balancing procedures... if I put the B&M flex plate on for an externally balanced engine and it is already balanced then it will vibrate.. Right??? Bill

RacerHog

Bill...If you can look at the dampener... (if it is the OEM one) if it has a weight in back on the inside? you should have an 'External balanced crank' and you will need the weight on the back side of the engine 'Converter weight'

And like Lynn Said, If you have like a 'fluid dampener'... Your just going to be at the crap table throwing the dice.

Big Question?????? What happened to the converter that was in the car?

440roadrunner

Here are the steps I would take.

1....You seem to think this might be internally balanced. That is going to take a LOT of special crank work. As I said, if these engines could have been easily balanced, the factory would have done so So the first step is to insure whether it's balanced internally or not. Pull the pan, examine the crank, and look for special balancing, IE "Mallory Metal" Maybe re-contact the rebuilder. I would DOUBT this engine is internally balanced While you are at it, make sure this is actually a 360. Somewhere, this is cast right on the side of the block. "Normally" it is encoded in the long stamped number up on the driver side front of the block, below the head parting line. But this may have been XXXX's out by the rebuilder.

2.....Ignore the balancer, it could have the WRONG balancer

3.....Just LOOK at your converter. A 360 weighted balancer has a big obvious weight, or maybe two of them. Internal balanced converters have very small weights to balance irregularities If you describe what you see we can advise. The thing is, weights vary with OEM and aftermarket converters

4......To fix this, assuming you need a weighted converter, you can in theory weld weights to the converter, but far more sure, far easier, and far more reversible is to buy a BM weighted flex plate. These ALSO vary in production. Some had weights, but the later models had a big half moon cut out of one side. In other words, instead of ADDING weight, BM instead removed it from the opposite side.

pro-tech

Here's what we got.. YES it is a 360... castings on the side of the block and the rear main cap is large and that is why I had to but a new oil pan to fit the 360.. It does have a harmonic balancer on the front of the engine the number on that is 85985 025 9 and just like that with the spaces... There was no weight on the converter because the car and transmission were a 340 but it had a 318 set up in it that was cracked... So I put the 360 in it as stated above.. The converter that I am putting in the car is one that he is building out of my 318 converter.. I am still not sure if I need it to be balanced or not... My big question and maybe I'm slow or something is if it balanced by the damper like a 318 why would the converter or flex-plate need to be balanced if the 318/340 don't have to be.. And it didn't vibrate.. It just doesn't make sense to me... If I need to I can have him add the weight but how does he know where to put it if it is a counter weight....Bill

pro-tech

Just to be safe I ordered a B&M flex-plate for a 360 with 904 externally balanced... And I hope and pray it doesn't vibrate after it is back together... that's what this car has turned into... a gone with the wind car and I have spent more money than I have driven it.....Bill

RacerHog

Here you go Bill...

They could not raise the block decks to help with a longer stroke, because the budget did not include altering the automated block and assembly lines to that extent. Weertman and others worked around that, using the same connecting rod as the 318, but reducing the height of the piston from the pin to its top, and cutting the radius of the crankshaft counterweights so there would be room at the bottom of the stroke. While that solved the space issues, the engine was now out of balance, so weights were added to both ends of the crankshaft assembly. That meant redesigning the torque converter flex plate and flywheel, and adding an offset weight to the vibration damper on the front of the crank.

This was the cause of the external balancing.... But Like 440 aid... If you have the rotor asm balanced then you could use all the neutral stuff...

RacerHog

pro-tech

Thank You Bob, And it was good talking with you!!! As always you helped me out of this problem that seems to be a Mopar snafu and an engineering F up... Just so everyone here is up to speed and for future reference My engine has got a forged crankshaft and is internally balanced and had the balancer listed above... which explains the no weight on the converter... And this $400 engine with 20 miles on it just keeps getting better... drinking and driving just doesn't pay for the guy that totaled his truck with 20 miles on a fresh rebuild but it sure helped me in this case... ...Bill

TVLynn

If it is a forged crank ? It may have a stroker kit in it ???

pro-tech

That might explain why it runs so good... And would be another plus.. Who knows what the guy that put it in his truck was doing...They told me it was out of a D100 maybe it was a built Lil Red Express ... His loss is my gain...Bill