360 engine vibration

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I was just looking at the JEGS item and will go for this. JEGS Harmonic Balancer for Chrysler 360
Part Number: 555-51671


 
nm9stheham, interesting what you say about the damper frequency range, the vibration I have is lower than that (I think). As I said before it is as if it has dropped one or 2 cylinders. So I think the seafoam and oil change is still to do incase it's a stuck lifter. So at least I have 2 things to sort out.
 
Yes, 6-7 kHz is 6000-7000 cycles per second... no way your derriere is going to respond to that frequency range LOL. Your vibration range is probably in the 10-20 cycles per second range.
 
nm9stheham said:
Yes, 6-7 kHz is 6000-7000 cycles per second... no way your derriere is going to respond to that frequency range LOL. Your vibration range is probably in the 10-20 cycles per second range.
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Yes agreed, although the pulley does have a wobble and looks to have a wobble on the inner part too? I friend of mine is going to run it up on the lathe and see how bad the wobble is, Either way new pulley on order.

whats your thought on this one? from Rock Auto. Seems to be the same part?

https://www.rockauto.com/en/moreinfo.php?pk=5430834&cc=1070435&jsn=480

My preference for using Rock Auto is I get an upfront cost for UK shipping an import duty at checkout. With JEGS I need to pay import duty when it arrives and then it gets delivered adding further time to arrive.
 
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IMHO, looks like a stock replacement part.. For cruising use, probably OK.

Any rubber parts being made in China and India these days are a real gamble. Motor mounts and strut tops are a great example: buy from there and they may be OK or may just as likely be trash. I just don't know where this one is made. So not much help....
 
nm9stheham said:
IMHO, looks like a stock replacement part.. For cruising use, probably OK.

Any rubber parts being made in China and India these days are a real gamble. Motor mounts and strut tops are a great example: buy from there and they may be OK or may just as likely be trash. I just don't know where this one is made. So not much help....
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Yes I known what you mean, however who's to says the JEGS part is US made? the descriptions and spec are identical. Ive asked JEGS where it is made.

or this one?
https://www.rockauto.com/en/moreinfo.php?pk=292152&cc=1079984&jsn=484
 
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uber cool said:
Yes I known what you mean, however who's to says the JEGS part is US made? the descriptions and spec are identical. Ive asked JEGS where it is made.

or this one?
https://www.rockauto.com/en/moreinfo.php?pk=292152&cc=1079984&jsn=484
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Exactly....As long as you are going with the OEM replacement parts, it is hard to know. So the choice becomes that, or a much more expensive, race rated one. For a street car, I know I would try one of the cheaper ones..... but no one can really tell you how good and reliable it will be; that just seems to be the nature of replacement parts these days.

There are valid reports of rings shifting and even flying off, but how hard the engines were used, I don't know. My son's 340 has a Pioneer OEM type damper on it, but has not been run very hard in it's 1000 (or so) miles.
 
George Jets said:
Say Uber Cool, a little off post here.

I noticed you have other than stock bucket seats in your 71 A Body Swinger. If you ever choose to put original Bucket Seats and Seat Tracks in, here are pictures of the correct Seat Tracks you need. These went into a 1972 Duster, they fit 70 - 72 A Bodies.

They are difficult to identify at swap meets and online sales as to what is correct for your car. Even the B body tracks look somewhat close as do the Cuda E body tracks of the same years, but do not work or fit, not even close.

I made fiberglass copies of these so that I have them for future reference and comparisons. I might even be able to make up some steel copies if I ever really get up against it off of these patterns. Aftermarket new 72 A Body tracks are available online, get ready to pay the big bucks though. Good to know what you are looking for and have plenty of time. Might be able to find a good price on a working set. File these pictures away if you think they could be handy in the future.


View attachment 1715299327


View attachment 1715299332
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Thanks the seats I have are out of 2001 Jag XK8, but I'm not 100% sure I want to to install these. I do have the original bench seat that I may put back in.
 
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Slightly worrying feedback, the damper spins up true in the lathe! This is only gripping it on the outer surface of the damper (where the oil seal runs), so going to check the hole for any damage or anything that could cause offset off the damper.

Tonight I'll re check the crank with another DTI and more steady magnetic base. It was a bit late the other night and a only crudely checked with DTI as I was fairly sure it was the damper at fault.

I'm now thinking it could be a crank issue so can see the sump coming off! Bugger!
 
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That is indeed unexpected based on the ring's wobble in the video. I would have expected the ring to be offset a bit. The pulley edge in the video does not seem to wobble at all but if the hub or crank snout was off, I would expect the pulley to wobble more than the ring.

If you pull the sump, then you can check out the crank for any deep holes in the counterweights or any slugs of metal installed in them. Plus rod part numbers.
 
George Jets said:
Hold your horses here a minute, You are over thinking this way too much. Keep it Simple.
You just need to install the new damper.

If you go back to the video you put up for us to see where you are rolling over the engine and showing us the wabble on the damper at the timing marks on the front timing chain cover. You will see that the center of your old damper hub is running true and straight, as the front pullies are running true and straight at the same time. It's the outer ring on your damper that has moved and is wobbling. The cushioning rubber between your damper hub and it's outer ring has failed, too much age on it as it is shrinking, drying up, and getting hard, after 40 years of service life. It's time to replace the damper with a new one. End of crankshaft is fine and is running straight and true.
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I hope I am over thinking this, currently sat at work googling 2nd hand cranks or short blocks LOL. On a plus point I've prepared myself for the worst.

However the damper has zero wobble when in the lathe inner or outer, yes the rubber is out of position and not running true. I just dont see the same wobble or any wobble as on the engine. Yes a new one is still a good idea and on the parts list. I was convinced it was the damper but having seen it run true in the lathe it doesn't make sense therefore I need to revisit the crank as my DTI check was very crude and late at night!

I'll post back in a few hours once I've checked again. I'll leave it on that cliff hanger!
 
George Jets said:
You pulled the damper outer ring back straight again when you pulled on it by hand during removal or helping it off with a prybar and pushing on the outer ring at that time.

Put the damper hub back in your vice, if you pull hard enough on the outer ring you can probably pull it off by hand, or at least easily move it with a small pry bar. She's wore out my friend !
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sadly the outer ring is fixed hard to the inner ring , no movement what so ever , Used a puller to get it off and didnt touch the outer. The only thing offset on the damper is the rubber. Let see what I find tonight
 
It is not making 100% sense to me at this point so it seems wise to see what the runout checks on the crank snout show. It is a good thing to double-check, IMHO.
 
I'll check again, tonight. Remember I dont have next day delivery for parts, so I'd be twiddling my thumbs for 2 weeks waiting for the damper to arrive. I need to be 100% sure on this is the problem I'll video the crank DTI check and video it end on close up whilst cranking. I have a small lathe at home and if the damper will fit in it I'll video that and then try it back on the crank again.
 
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Well, after another 4 hours of theory, what if's, measurement, head scratching etc I think Ive found the cause of the damper wobble and it turns out we are all correct.

Yes it didnt ring 100% correct when the damper was run up in the lathe and was true that the damper was at fault. However I believe it is the damper at fault. But not for the reason of a loose or misaligned outer ring due to rubber deteration.
Its late again and I need to get to bed, I'll post a video and reasoning tomorrow but the summary is I believe the damper has had a defect when it was manufactured. Where the hole and rear face have been machined parallel to each other but slightly wonky and hence causing the wobble when mounted on the crank. But when gripped on the outer of the shaft where the oil seal runs the damper runs true. For the damper to be made it must be machined one one side then taken out of the lathe and then turned around, if misaligned and we only need a 5 thou misalignment here it will cause the 40 thou wobble on the outer edge. Photos and video to follow tomorrow.
 
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A photo of the crank nose stamped KC, anyone know what this refers to? Also number on inside of crank, or it could be be the lower cam timing sprocket S 359, what does this refer to?

Measured a 40 thou wobble on outer edge of damper when installed on crank and can simulate this on the bench, see video here


At one point I wondered if the engine had come out of a crashed car with heavy front end impact , damaging damper or nose of crank. However timing cover is stamped 78, and I would assume if it had had a heavy front end impact to bend crank or damper this alloy cover would have cracked and been replaced.

DSCF6267.JPG


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DSCF6309.JPG
 
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Don't fret over the crank bolt runout. Replace it with a new grade 8 if it bothers you, but make sure you keep the heavy washer. Final torque is in the range of 135 ft-lb, which is needed to tightly 'lock' the damper to the crank, so as to couple the crank vibrations into the damper.

BTW, does the damper just easily slip onto the crank snout? If so that is a problem. It should be an interference fit and should need to be pulled on or off. The 'true' surfaces that aligns the damper to the crank is the inner surface of the damper's hole, and the outer surface of the crank snout. The 'true' surface is NOT the back surface of the damper hub that contacts the crank sprocket (although it should be very close anyway).

If there is any looseness between damper hub and crank snout, then the damper inner diameter is damaged or the crank shout has been damaged. If it is the crank snout, then there are repair sleeves available. And, if either is loose, then any bend in the bolt or slight misalignment in the threading inside the crank snout would force the damper to go crooked when the bolt is tightened. So that could be the whole issue there.

Please take micrometer measurements on the crank snout OD in a few places and report for comparison.

BTW, nice thorough video and good narration! IMHO, you have worked this over pretty well.
 
I'll be buying a new bolt and washer with the damper. The damper is a tight interference fit on the crank and needs to be pulled on with the bolt and pulled off with a hub pulley. I've checked the damper with the DTI when partially seated too and its the same amount running out of true, that's what got me on path of a manufacturing defect. Anyway parts on order.
 
RustyRatRod said:
Good grief.
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I get your comment and chuckle with it in agreement. If this was a VW flat four or pretty much any other common engine in the UK I would have searched through my spares box and tried another in 5 mins. However I don't have that luxury and if I'd ordered every part I though was causing this issue or wrong with this Dart to date I'd have spent thousands of $$ in parts, shipping and import duties to UK. For example the $68 damper by the time its gets to my door has cost $195.

So I have to take a different approach. If you watched my video I think you'll have grasped even I am at the the point of FFS this has got to be the problem. What threw me was the problem with the damper wasn't the expected deterioration of the rubber and thus wobble/slip of the outer damper part.

If it is a machined defect from when it was manufactured I have to assume this isn't an OEM part that has been on the engine from 1978 and someone has fitted later, probably when installing the V8 in this Dart.
 
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uber cool said:
I'll be buying a new bolt and washer with the damper. The damper is a tight interference fit on the crank and needs to be pulled on with the bolt and pulled off with a hub pulley. I've checked the damper with the DTI when partially seated too and its the same amount running out of true, that's what got me on path of a manufacturing defect. Anyway parts on order.
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OK, good, just checking.

uber cool said:
For example the $68 damper by the time its gets to my door has cost $195.
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THIS is the 'good grief' part IMHO.
 
Ok parts arrived. New damper and new oil seal fitted. Good news is the pulley no longer wobbles on the inner part and outer part. So balancer and pulleys run true. Bad news is its still has this vibration.

But im pleased I have the crank correctly balanced front and rear now. Run the engine for about 45 mins with sea foam in and no improvement, but i will run it for a bit long and remember its not yet Uk registered so i cant go on a drive :( .

So revisited the compression readings and drawn them out as the engine is instead of a list 1 to 8, and I think Ive found something interesting the even bank 2- 8 are lower readings than 1 -7. The readings are the same wet , which points to valves. Now you remember this is the side that had the valve rockers on crossed over and the pushrods had worn a grove in the head from dragging. Maybe these valves are burnt, carboned, rusty all any of these to create a slight leak off? Im going to do a cylinder leak off test tomorrow which might tell more.

The first readings for 5 and 7 I couldnt be bothered to remove the hedman headers to get the compression gauge in place, instead just aknowledged i had good compression with my finger over the hole. But in the end I thought I need to to prove a point with accurate data, so loosened the header enough to get the compression gauge in place.

DSCF6334.JPG
 
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Different deck heights, perhaps. Can effect compression and/or valve opening/closing which effects compression readings if this has hydraulic lifters and the pushrod length is such that the lifters are near the edge of their travel range. My son and I got a 5 psi average difference between left and right banks even with careful setting of deck heights.

I did not want to say it before and be a wet blanket, but I am not surprised on the damper not fixing the vibration. 10-15 psi difference in left and right banks ought not to cause any noticeable vibration... the firing sequence is not left-right-left-right all the time. So I don't think this is your issue.

BTW, the idea that the crank is properly balanced is debatable..... that depends on the pistons, rods, etc..... which seem to be unknowns at this point.

EDIT TO ADD: Those compression numbers are NOWHERE near to stock numbers. So it seems pretty certain that the pistons are not stock. That leads to questions on overall balance of the engine.
 
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I always like to think Simple. You are good with the 4 cylinder opposed VW engines, in Stock or mild performance they will foul spark plugs all the time, especially if the fuel air mixture is a bit rich.

You may have something so simple as a fouling spark plug, they can do funny things.
Put a brand new set of spark plugs in it, mopars were Built for Champion Spark Plugs. Lots of guys are having good luck with Autolites. Hopefully you are running the mopar brain box and ballast resistor ignition system. Simple is good.

Give that a try, it either gets better or gets worse and leads you to the answer of how to get things right. Keep working through it.

Process Of Elimination !
 
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