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07-04-2017 #1
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- Dec 2014
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- Murfreesboro, Tennessee
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First time engine start, run and vibration.
Hey y'all. I finally got the car going. Once I get things sorted out I'll update my car on here. It's a 71 455. Stock bottom end. It is internally balanced. Summit racing steel flywheel. Here's what's going on. I start the motor and it idles liked it should. As I bring up the rpms a vibration appears. It's a quick vibration. It does not take that many rpms to get it to do it. When I shift gears and the rpms comes up cause the fitech is still learning I can feel it. I'm leaning towards the harmonic balancer, but I would liked some advice before I pull things apart. Thanks in advance.
Ben
1971 Firebird Formula 455HO 6 speed
2017 GMC Sierra Denali Ultimate Pearl White 6.2L
2013 GMC Sierra 5.3 6 Speed Pearl White, SLP 1.9L Supercharger(Sold)
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07-04-2017 #2
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- Mar 2015
- Location
- FL
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- 318
Make sure its not something simple like a plug wire being disconnected. And make sure you got a neutral balance flywheel since bottom end is internally balanced. Not sure how harmonic balancer would cause a vib... unless the rubber is loose or something
-Mitch
G8 GXP, White Hot, Auto, bone stock
68 Firebird, 428 Pontiac, CNC'd KRE Al d-ports, hyd roller, EFI, TKO600, TCI Eng complete chassis, Ridetech, Kore3 C6Z brakes, C5Z 18" with 315 rivals x4, C6zr1 mufflers
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07-04-2017 #3
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- Dec 2014
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- Murfreesboro, Tennessee
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- 134
Flywheel is for an internally balanced motor.
1971 Firebird Formula 455HO 6 speed
2017 GMC Sierra Denali Ultimate Pearl White 6.2L
2013 GMC Sierra 5.3 6 Speed Pearl White, SLP 1.9L Supercharger(Sold)
07-05-2017 #4
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Does the vibration appear if you simply raise the RPM while not moving?
Andrew1970 GTO Version 3.0
1967 Cougar build
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07-05-2017 #5
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- Dec 2014
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- Murfreesboro, Tennessee
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- 134
Yes.
1971 Firebird Formula 455HO 6 speed
2017 GMC Sierra Denali Ultimate Pearl White 6.2L
2013 GMC Sierra 5.3 6 Speed Pearl White, SLP 1.9L Supercharger(Sold)
07-05-2017 #6
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- Sep 2004
- Location
- Arizona
- Posts
- 238
Check the flywheel for runout and wobble. I had one that did not seat on the crank, I should have noticed, cause the transmission was difficult to stab, but it shook like a beast.
07-05-2017 #7
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- Dec 2014
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- Murfreesboro, Tennessee
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- 134
This one isn't shaking that bad.
1971 Firebird Formula 455HO 6 speed
2017 GMC Sierra Denali Ultimate Pearl White 6.2L
2013 GMC Sierra 5.3 6 Speed Pearl White, SLP 1.9L Supercharger(Sold)
07-09-2017 #8
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- Dec 2010
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- Fredericksburg, VA.
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- 3,164
Back to the harmonic balancer, is it old or new? Stock or aftermarket?
07-09-2017 #9
Registered User
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- Dec 2014
- Location
- Murfreesboro, Tennessee
- Posts
- 134
Looking to be the flywheel. Was sold the wrong one.
1971 Firebird Formula 455HO 6 speed
2017 GMC Sierra Denali Ultimate Pearl White 6.2L
2013 GMC Sierra 5.3 6 Speed Pearl White, SLP 1.9L Supercharger(Sold)
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