Vibe Question for the Engineers
Thread Starter
Racer
Joined: Sep 2019
Posts: 349
Likes: 44
From: Spokane, WA
Vibe Question for the Engineers
1. To set the stage: All rotating accessories have been eliminated as a potential problem. Clutch/Flywheel package is balanced as an assembly. New Pilot bearing. New trans mounts and engine mounts. Nothing is hitting the frame. Ignition and fuel eliminated as a source. New OEM style harmonic damper. Base model 350.
2. Problem: Engine vibe around 3200 RPM so that is what, about 213Hz. Can't test the multiple at 6400 RPM because, well, the engine can't do that. Half would be 106 at about 1,600 RPM. I don't really feel the vibes there.
3. Question 1: What is the typical Hz damping range for an OEM style damper on a SBC 350 CID?
4. Question 2: Would an aftermarket damper with a wider frequency range possibly eliminate this issue?
5. Question 3: What are the possible causes of 213Hz vibrations in a SBC?
Thanks!
Sam
2. Problem: Engine vibe around 3200 RPM so that is what, about 213Hz. Can't test the multiple at 6400 RPM because, well, the engine can't do that. Half would be 106 at about 1,600 RPM. I don't really feel the vibes there.
3. Question 1: What is the typical Hz damping range for an OEM style damper on a SBC 350 CID?
4. Question 2: Would an aftermarket damper with a wider frequency range possibly eliminate this issue?
5. Question 3: What are the possible causes of 213Hz vibrations in a SBC?
Thanks!
Sam
Thread Starter
Racer
Joined: Sep 2019
Posts: 349
Likes: 44
From: Spokane, WA
Thread Starter
Racer
Joined: Sep 2019
Posts: 349
Likes: 44
From: Spokane, WA
Don't know and no. Bought the car log after the engine rebuild. The starting assumption is that it is correct...which may not be the case. But, I have to start somewhere to eliminate all other possibilities because an improperly balanced rotating assembly means I get to rebuild the engine.
Dr. Detroit
Joined: Mar 2012
Posts: 10,095
Likes: 4,025
From: New Braunfels Texas
Don't know and no. Bought the car log after the engine rebuild. The starting assumption is that it is correct...which may not be the case. But, I have to start somewhere to eliminate all other possibilities because an improperly balanced rotating assembly means I get to rebuild the engine.
You could try bolting a high quality balancer (Like Pioneer) on it and see if it changes......but it would be unlikely unless your current unit is dry rotted and/or spun.
EDIT: Re-reading your OP....I see you have a new one on there already.
Jebby
Last edited by Jebbysan; Mar 29, 2021 at 01:20 PM.
Thread Starter
Racer
Joined: Sep 2019
Posts: 349
Likes: 44
From: Spokane, WA
Has it done it the whole time since you have purchased it? If so...then yeah, it is out of balance if you have ruled out all other things.
You could try bolting a high quality balancer (Like Pioneer) on it and see if it changes......but it would be unlikely unless your current unit is dry rotted and/or spun.
Jebby
You could try bolting a high quality balancer (Like Pioneer) on it and see if it changes......but it would be unlikely unless your current unit is dry rotted and/or spun.
Jebby
Pro
Joined: Apr 2012
Posts: 696
Likes: 193
From: USA
1. To set the stage: All rotating accessories have been eliminated as a potential problem. Clutch/Flywheel package is balanced as an assembly. New Pilot bearing. New trans mounts and engine mounts. Nothing is hitting the frame. Ignition and fuel eliminated as a source. New OEM style harmonic damper. Base model 350.
2. Problem: Engine vibe around 3200 RPM so that is what, about 213Hz. Can't test the multiple at 6400 RPM because, well, the engine can't do that. Half would be 106 at about 1,600 RPM. I don't really feel the vibes there.
3. Question 1: What is the typical Hz damping range for an OEM style damper on a SBC 350 CID?
4. Question 2: Would an aftermarket damper with a wider frequency range possibly eliminate this issue?
5. Question 3: What are the possible causes of 213Hz vibrations in a SBC?
Thanks!
Sam
2. Problem: Engine vibe around 3200 RPM so that is what, about 213Hz. Can't test the multiple at 6400 RPM because, well, the engine can't do that. Half would be 106 at about 1,600 RPM. I don't really feel the vibes there.
3. Question 1: What is the typical Hz damping range for an OEM style damper on a SBC 350 CID?
4. Question 2: Would an aftermarket damper with a wider frequency range possibly eliminate this issue?
5. Question 3: What are the possible causes of 213Hz vibrations in a SBC?
Thanks!
Sam
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
Thread Starter
Racer
Joined: Sep 2019
Posts: 349
Likes: 44
From: Spokane, WA
Thread Starter
Racer
Joined: Sep 2019
Posts: 349
Likes: 44
From: Spokane, WA
For a while I thought it was ignition related as well. And it may still be. New plugs, new wires, new cap, new rotor and switched to Breakerless SE ignition. Coil in spec. Still could be misfiring for some reason. Seemed to get a LITTLE better...After all that, not sure how it could STILL be misfiring.
Pro
Joined: Apr 2012
Posts: 696
Likes: 193
From: USA
So tell us how intense the vibration feels? Compare it to something we have all experienced, like an electric tooth brush or driving to far to the right over the vibrating road strip ...
Thread Starter
Racer
Joined: Sep 2019
Posts: 349
Likes: 44
From: Spokane, WA
I know, this is weird.
Pro
Joined: Apr 2012
Posts: 696
Likes: 193
From: USA
suitable bolting locations? head bolt hole for accessories, on and accessory it self, exhaust bolt , in take bolt, etc you get the picture..
Last edited by CAMS69; Mar 29, 2021 at 03:13 PM.