I am chasing a harmonic vibration felt starting around 3300 RPM and viiiibbbesss then gone, then viiibbbes and you are going from 3300-say 5000 RPM. Shakes the shifter. This happens either moving or static, clutch in or out doesn't matter. So, not the trans or drive shaft.

I am going through all the preliminary stuff:
All cylinders are firing
All wires check in terms of resistance
Points fairly new 30* dwell, new cap, new rotor
Timing 16* all in by 2,800 RPM
Re-setting curb idle mix

So I am down to a few things
1. An improperly balance flywheel. Original flywheel was surfaced and balanced by a local shop. Buuuuttt...the car did this before...so probably not it. Its possible that it was a bad pressure plate before, I change out the clutch package and maybe ended up with an improperly balance flywheel instead.
2. Changed out the harmonic balancer with a GM replacement. Still the same vibe. BUT, I did notice that it wobbles a little. Yes, I have a balancer tool.
3. MAYBE a fan clutch? I am going to take that off and try it without it.
4. Worst case is a bent crank...but the front cover crank seal has never leaked.

Has anybody ever had a brand new harmonic balancer be bad right out of the box?

 

You need about 20 degrees more timing.....first off.
What are you working on? 327? 350? 427?

Jebby

 

Something is wrong, the balancer should not be wobbling at all. Did the old balancer wobble the same?

 

Has this engine always vibrated like this as long as you have owned it? If so, it could be that the crankshaft is out of balance.

 

^^^^ THIS ^^^^
and what're viiiibbbesss and viiibbbes ? first nation's Spokan ?

most "balancers" don't balance; they dampen

sure you've got a match: damper to motor ? neutral / internal / external / hybrid balance ?

e.g. lotta cheaper 383 need a 400 external balance damper, 427 damper's internal-neutral while 454 typically external. Depends on how motor was assembled.

 

350. 16* initial.

 

Never made note whether it wobbled or not. I don’t remember it doing so.

 

meaning it’s not a constant vibration, but rather cyclic. As I am going from 3k-5k, the vibration pulsates. Vibrates for maybe a second or two, then gone, then comes back...all while the engine rpms are climbing.

 

Very possible. It’s a 355...rebuilt back in the late ‘80’s by the PO. I am trying to eliminate everything before coming to that conclusion.

 

Do you have the correct fan clutch/fan?
It is the correct size for the water pump shaft?

 

It is a 7 blade OEM from an AC car. Fits the snout just fine. Same ID/OD match. Car should have a 5 blade. Maybe the fan clutch is bad but doesn’t seem like it.

 

I would start by taking the belts off and run the engine to see if the vibration goes away. If so, start adding the belts one at a time to narrow down the various components. It could be the water pump, fan, fan clutch, A/C P/S pump. alt. etc. Jerry

 

did that for the AIR pump, but no difference. Have not done it for the rest yet. Water pump is new. No AC. Certainly could be PS. I’ll add that step to my plan.

 

Ah....way it was written sounded like total

Jebby

 

yep, it sure did. My mistake.

 

what do you KNOW for a fact about the internals of motor ?

is it a rebuilt 69 350? or some other year? If so which year ?
was the aft end of crank (surface where your fw bolt-holes are) perfectly round shape ? or an obviously irregular shape ?
rather than 355, could it have been converted to a 383 ? or built from a 400 ?
What're you Certain of ?

-add-
does the flywheel have a balance weight cast-in the motor-side (not disk side)? or Not ?

 

Pull the belt then run it...Ive seen dampners with a tiny bit of runout that didnt affect antyhing
A funky plug wire can cause strange vibrations..one thing at a time.
you said it did it before?

 

It is 010 block with the correct HY broadcast code (Base '69 350 4-speed, no A/C) and matching VIN. It has 4.030 holes (measured when the heads were off) with standard flat-top pistons with valve reliefs. Original forged rods. Caps and 4-bolt mains are all numbered by a punch so the engine has been apart. Correct iron intake. Correct date coded heads (small valve...but they are off the car awaiting a rebuild. Dart Iron Eagles 180's are on the car currently). Had a TRW replacement base cam which was replaced with a Crane 274H06. Carb is a 7029203 (correct for the car), distributor is from a '74 based on the band. Water pump is a service replacement. PS pump is original. Alternator is a service replacement. Coil was just replaced with a service replacement. AIR pump is a service replacement. Pulleys are are OEM.

 

Weirdly, it did...but that was when I first got the car. At the time, the front and rear alignment was total crap, the u-joints were bad (drive and half-shafts), the yoke bushing was worn, the rear trailing arm bushing were bad, rear wheel bearings bad, and a hacked up shifter. ALL of that has been fixed and returned to factory spec. Drove much better. Pulled the trans and replaced the clutch package, rebuilt the Z-bar, etc. The flywheel was original and had not been resurfaced. Took it to a machine shop and they resurfaced, balanced and put a new starter ring on it. Put it all back together, ran fine. Zipped up to 4500 smooth as butter. Now, we have this new vibe thing.

I really did think it was ignition related...checked all the plug wires for continuity and resistance. All are good on a per foot basis. All cylinders are firing. Points are good. Dwell is good. Plug gap is .035. Plugs look good. Distributor was shimmed to the spec in Lars's paper (.007 I think...I'd have to look it up to be sure). I thought maybe it could be a lean condition...especially after the cam and head swap. Bumped the jets from a 71/45 combo to a 73/45 combo adding about 9% more metering area. Have not had the car started since then.

 

internals I askedbecause you may have a mismatch
do you recall what end of crank looked like? or back of flywheel ?
makes no diff what heads etc are on it.
only the rotating & reciprocating bits that rotate with or around crankshaft do affect-control balance.

maybe it's an internal 355 w/ wrong external damper and/or flywheel on it.; hence the Qs