318 poly vibration

65GUS

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Hi, i have a 65 fury with the 318 poly motor which has a vibration in it. Very noticeable at certain RPMS ( no tach) but at 15-20 & 35-40 &50-55 mph. Seems to smooth out above those speeds. Replaced timing gears and ( chain was stretched and went to double roller) 6 months ago, vibration was noticed along with balancer wobble soon after. Put new balancer on ,but still have vibration. Took pulleys off several times looking for problem, but im at a loss. Maybe something internal ? The poly runs like a champ but with a vibe. Any ideas or help. Thanks
 
I'm going to try and look things over tomorrow . And i will dbl check motor mounts.thanks
 
No, it has a motor vibe when parked and also when all drive belts are un hooked
 
No, it has a motor vibe when parked and also when all drive belts are un hooked
Then it's probably not the mounts either, although still easy enough to check and cross off the list.

You need to give more details.

Automatic? Standard?

If standard shift, clutch in or out?

If auto, have you checked the flex plate? Neutral or park?

The more details the better. I would have said driveshaft too based on the "MPH" description as vibration coming and going is classic driveshaft issue.
 
If it's an auto transmission, do your tests in neutral engine /trans warmed up(20 minutes at least)or the TC may not fill correctly with fluid and cause an imbalance...
The TC should fill quickly enough after placing in neutral(It won't if left in park). If it doesn't an the trans slips, it's likely the transmission pump starting to fail.

Keep us posted on what you find.:thumbsup:
 
Hi, again. Yes its an auto 727. Had a friend come over whose a mopar guy, he says balancer looks fine, so we checked ignition timing, was way off, was 20° at idle ! 40° full advance. Vacuum unplugged. IDK how or why its set there.maybe new timing gears didnt get set straight up dot to dot IDK. anyways it runs better, but still has a vibe at a certain rpm. I re-checked the vibe after an 30 minute cruise,fully warmed up, still there, smooths out past that certain rpm im thinking maybe a compression test may yield some internal info ? May just let it progress until it shows me where its at. Frustrating
 
Yes , i know motor has adj. Valves. They were adjusted last summer by a very qualified mechanic.replaced original dampner with a new one for an LA 318 as new poly dampners are N/A.
 
Compression test will tell you something, let us know. If you could use your cell phone to shoot video and sound of the engine running at the tail pipe, that would tell us a lot.
 
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