360 engine vibration

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uber cool

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Hi, new to the Dodge dart and have an issue with engine vibration over about 1500 rpm. Now a little background first , its a 360 engine mated to a 727 transmission , im based in the uk and bought the car last year from Texas. Now it wasn't an original 360 ( I wish) or even a v8, car was originally a slant 6 904 box and 7 1/2 rear axle. someone has spent a bit of money uprating the back axle to 8 3/4 fitting a 727 trans and rebuilt 360 engine, most of it looks new is recently rebuilt, i think it was a stalled restoration, i got it from a texas classic car dealer.

now back to the vibration, the car is not not UK legal, so i cant take it for a run. I've read loads of threads on here re harmonic balancers and internal and external balanced cranks. ive tried the obvious and removed drive belts, checked firing order, plugs firing, exhausts not rubbing on body etc. I now started to look around the crank balance, the front pulley looks to have an external balance and ive rotated and looked all around the converter and cant see an balance weights, so i'm thinking I will need the B&M balanced flex plate, as it look to be a stock flex plate. any ideas or suggestions?
 
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the car its self

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Curious, is vibration there in Neutral and in Park when you bring idle up? It never smooths out past 1500 rpm?

Sweet Dart, btw!
 
Or get a B&M flex plate for a 360 if you don't have weights. Did you rotate the converter to see if there are any weights? The balancer looks like it's from the late 80's or early 90's 360. Is this a magnum or premagnum engine?
 
I think he should look into the proper 360 torque converter with the weights...

I see a few chipped teeth on the one that he has now (unless that's just a dirt/grease spot)... If that is lined up with the starter after he turns if off, it may not be able to turn the engine with the starter... I would get a new converter for sure...

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krazykuda said:
I think he should look into the proper 360 torque converter with the weights...

I see a few chipped teeth on the one that he has now (unless that's just a dirt/grease spot)... If that is lined up with the starter after he turns if off, it may not be able to turn the engine with the starter... I would get a new converter for sure...

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Thanks guys, great feedback,

I will recheck the converter , but im sure it's fine and that is just as shadow in the photo.

It vibrates in neutral, park and in drive (I had a sneaky drive down the road) it feels like it not running on all cylinders but ive checked the plugs and leads and checked all firing. I'm going towards a balance issue, as I think I see external balance on the front and non on the rear. The engine I think is's a late 80's 360, I have a photo of the engine number somewhere I'll post up a photo of it. Only other thing to thorw in the discuss is at present its running open headers as i need to make up the exhaust, but i can see this causing the issue??

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Ive spun the converter all the way round and cant see any welded on weights.

How would I check the engine is magnum or premagmum. I suspect the engine is a fresh rebuild or crate engine as all the fixing look new and i doubt it has done any mileage.
I off to the states next friday 21st oct for 2 weeks road trip ( south Cali) , so would be good to arrive with a shopping list :)

dont look at the wiring ( Arrgh) and the air filter got binned straight away!
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A complete engine casting number would make that easy to answer.... your pix shows just part of it. I can see '....930-360-6', which would lead to a guess that it is a 4179930 casting, which would be an LA (pre-magnum) block. Does not mean it can't have Magnum heads on it though....

mopar casting numbers
 
ok thanks guys, think i might drop the transmission tomorrow to get a better look at the converter and flex plate setup
 
Decided not to drop the trans just yet. Instead continued to fabricate the exhaust so at least I can run it without my ears bleeding. Now with the exhausts on its obvious the vibration is there at even 800 rpm and just gets worse as it rev's up. checked and double checked the timing , firing order and plug gap. some other I got, engine number VIN is 9A171805 date stamp above this is 12-21-78 so assume that is 21st dec 1978 ?

Also noticed transmission mount is ripped is complete ripped in half, so that could contribute to it!
 
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Not all TCs have drainplugs. No biggie, just crank some heat into the welder.The weights only need to be tacked on;but the tack has to be serious.If it flies off at redline, it will do a lot of damage.
You can remove the weights from a spare TC, by grinding off the weld.But note where it/they came off. They have to installed in a very specific location on your present TC,AND they have to be of a specific mass, according to what the reciprocating assembly dictates.In other words;you can't just weld on any weight, anywhere!
Furthermore, you have no way of knowing what your reciprocating assembly wants. If it is not stock inside there, it will want a non-stock weight welded on. So;some experimentation may be required. Or some research, by/from the former owner.The location to weld the weight on may not change significantly. But the mass may. You gotta start somewhere.
 
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FWIW..... TC's without drain plugs can be drained by drilling a small hole in the outer edge and then a very short sealing screw installed. The drill has to be set up so as to not penetrate the housing more than a few thousandths of an inch, to avoid getting into the innards. I've never done it over concerns for metal in the drilling, but numerous trans shops did this for years as a regular practice. YMMV
 
Yeah, I installed a 1/8th pipe plug in every TC, in every tranny I ever changed the oil in.Otherwise you leave about 70% of the burned-out,wore-out, polluted,stinky,ATF, still in there.....but I didn't want to mention that,lol.
 
I am following this and also and have always had some vibration that I also believe are from my converter weights. When I had the converter installed they were overlooked and not tack welded on. Major Vibrations from car when driving and revving in neutral. This was years ago and I still remember it was bad. I contacted the shop and they tacked some weights on the converter whilst on the car. Not sure if it was done perfect but bad vibrations were gone. There is still some vibration around 2000 or so and it has been like this since 1991. Trans is toast now so New Converter and Trans planned. Car is a 1970 Duster 340 with a Mild 360 and 727.

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Sedanman said:
Or get a B&M flex plate for a 360 if you don't have weights. Did you rotate the converter to see if there are any weights? The balancer looks like it's from the late 80's or early 90's 360. Is this a magnum or premagnum engine?
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Do these B&M Flex plates come balanced for LA 360s? I am planning a fresh 727 and converter for my Duster 340 and would like more info on this option.
 
The damaged Trans mount is absolutly nessassary to fix before figure out the vibrations!
That can cause heavy vibrations!
The converter could be ok. I would try the b&m flexplate for external balance.

Nice Dart!
 
Fix the stuff you know is broken first. Can't narrow down what the problem is with stuff still for sure busted.
 
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