Vibration cause?!?!?!

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vntned

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Location
Gibsonville NC
Car in question:

'64 Dart 170 2dr sedan
360 0.060" over Speedpro H116CP pistons (measured 9.3:1scr)
Stock crank and rods
Comp Cams 268AH-10 cam
340 windage tray
Unported 587 heads with 1.88/1.60 valves
Eddy LD340 intake
Street Demon 750cfm carb
Stock style electronic distributor with FBO plate
Chrysler ignition with an Orange box
'67 A833 4spd trans
Ram HDX clutch
8.25 rear with a 3.55 SG

The issue is I've got a serious engine vibration that I can't nail down. The engine is smooth from it's 800rpm idle up to just over 2000rpm. From that point on a engine vibration increases until just over 3000rpm, then maintains that level of vibration through out the gear. It will do this in neutral or with the clutch in while parked.

When I built the engine I had the entire bottom end balance with the dampener and 360 flywheel. I've had this engine in the car for about 2.5years now, but I don't remember it vibrating like this when I first assembled it.

I've checked the balancer and it hasn't slipped or rotated and looks fine. Like wise my timing marks are still dead on. As far as timing goes, my at 18deg base and 36deg fully advanced. Now here's the part that's got me intrigued, the curve starts off around 2000rpm and is at full advance by 3000rpm. Same window of my vibration...


Could ignition or spark curve do this?!
 
vntned said:
Car in question:

'64 Dart 170 2dr sedan
360 0.060" over Speedpro H116CP pistons (measured 9.3:1scr)
Stock crank and rods
Comp Cams 268AH-10 cam
340 windage tray
Unported 587 heads with 1.88/1.60 valves
Eddy LD340 intake
Street Demon 750cfm carb
Stock style electronic distributor with FBO plate
Chrysler ignition with an Orange box
'67 A833 4spd trans
Ram HDX clutch
8.25 rear with a 3.55 SG

The issue is I've got a serious engine vibration that I can't nail down. The engine is smooth from it's 800rpm idle up to just over 2000rpm. From that point on a engine vibration increases until just over 3000rpm, then maintains that level of vibration through out the gear. It will do this in neutral or with the clutch in while parked.

When I built the engine I had the entire bottom end balance with the dampener and 360 flywheel. I've had this engine in the car for about 2.5years now, but I don't remember it vibrating like this when I first assembled it.

I've checked the balancer and it hasn't slipped or rotated and looks fine. Like wise my timing marks are still dead on. As far as timing goes, my at 18deg base and 36deg fully advanced. Now here's the part that's got me intrigued, the curve starts off around 2000rpm and is at full advance by 3000rpm. Same window of my vibration...


Could ignition or spark curve do this?!
Click to expand...

I don't know for sure but have you tried pulling out a couple degrees of advance and see if that makes a difference? What's the story with the car over those past 2.5 years, has it been sitting a lot? Might have old stale gas. Also within the past few years pump gas has been getting steadily shi**ier at least from what I've seen, might need to re-tune if that hasn't been done in a while.

My cousin's 440 in his '72 Polara got a terrible vibration because the idiots at the shop he took it to for a tune-up hooked up the spark plug wires wrong.
 
If it's detonating, that could be it. And that wouldn't be good at all. What are you running for octane?
 
No detonation that I can hear. I ALWAYS run 93octane fuel, and I drive it a couple times a week, 50-100miles maybe.
 
vntned said:
No detonation that I can hear. I ALWAYS run 93octane fuel, and I drive it a couple times a week, 50-100miles maybe.
Click to expand...

Yeah I would think that would be plenty with a 9.3:1 static. I had to pull a couple degrees out of mine at the top but I’m at 9.8:1 and can only get 91 octane.

What balancer are you running? Might not hurt to try a different one...
 
So problem has been mostly solved. I ended up throwing in a new Mopar distributor that I had sat aside for my trucks build. This did NOT make the vibration go away. I then put in a new set MSD wires and replaced the NGK plugs for some good old Champion plugs. Now, there is a slight vibration around 3k, then it goes away through the rest of the gear!
 
The motor mounts are only about 2yrs old and are rubber. The tranny mount is a red poly one from Energy Suspension. I haven't swapped it out for rubber one yet, but I do intend to.
 
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