[L98]: Internally balanced?
Drifting
Joined: Apr 2003
Posts: 1,292
Likes: 2
Re: [L98]: Internally balanced? (vader86)
That is a fact.
If you look at a 86 or earlier crank, the rear(where the flexplate/flywheel bolts on) is eccentric, sort of D shaped.
This is a balance weight, part of the crankshaft, external to the rear mainseal, but because it is part of the crank classed a as internal.
The 87 up motor crank (one piece mains) has a circular end, no integral balance weight, so the balance weight is part of the flywheel/flexplate. This is classed as external balance.
The front of the crank (350 lumps) is truly internally balanced in both cases.
The front of the crank (400 lumps) is externally balanced by a weight on the damper
383 (stroker 350) can be balanced any which way, since it is (usually a custom 350 conversion.
This also is a fact.
If you look at a 86 or earlier crank, the rear(where the flexplate/flywheel bolts on) is eccentric, sort of D shaped.
This is a balance weight, part of the crankshaft, external to the rear mainseal, but because it is part of the crank classed a as internal.
The 87 up motor crank (one piece mains) has a circular end, no integral balance weight, so the balance weight is part of the flywheel/flexplate. This is classed as external balance.
The front of the crank (350 lumps) is truly internally balanced in both cases.
The front of the crank (400 lumps) is externally balanced by a weight on the damper
383 (stroker 350) can be balanced any which way, since it is (usually a custom 350 conversion.
This also is a fact.
Melting Slicks
Joined: Jan 2003
Posts: 2,167
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From: What did the 5 fingers say to the face? SLAP!!
Re: [L98]: Internally balanced? (vader86)
All 86 and later.
[Modified by vader86, 5:59 PM 10/17/2003]
[Modified by vader86, 5:59 PM 10/17/2003]
Pro
Joined: Dec 2002
Posts: 746
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From: salem or
Re: [L98]: Internally balanced? (scorp508)
School of hard knocks. I had purchased a 383 stroker LT1 from an engine builder...bolted up my exteranls...the thing nearly shook apart.
It seems that the engine builder internally balanced the rotating assy and when I bolted up the "weighted" flywheel the thing was no longer balanced.
I learned that 1 pc rearmainseal cranks are not internally balanced from the factory and if you use the weighted stock flywheel on an internally (non-stock) rotating assy, it will really shake you up.
It seems that the engine builder internally balanced the rotating assy and when I bolted up the "weighted" flywheel the thing was no longer balanced.
I learned that 1 pc rearmainseal cranks are not internally balanced from the factory and if you use the weighted stock flywheel on an internally (non-stock) rotating assy, it will really shake you up.
Team Owner
Joined: Sep 2001
Posts: 62,140
Likes: 1,729
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Re: [L98]: Internally balanced? (flyersfan1088)
Close, but not quite. Early '86 still had 2 piece seal
And the manual does note the other mid-86 changes.
[Modified by vader86, 6:54 PM 10/17/2003]
Safety Car
Joined: May 1999
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From: Atlantis
Cruise-In I Veteran
Re: [L98]: Internally balanced? (VetNutJim)
Well pass the salt and the terriyaki sauce. I need it for this crow I'm about to eat.
I checked the flexplate on this 90 engine in the back and sure enough, THE FLEXPLATE has a small weight on it.
It's ALSO KEYED with a rollpin so you can't just mount it any old way like the old ones.
I'd just about bet the 91 is JUST like it... When did the 1 piece rear main seal come out? '87 ??
I WAS WRONG. VetteRacer was RIGHT. (And several other guys out there)
Now PASS that salt and sauce. I'm ready to eat. Wait, where's my dentures ??
:lol: :rofl: :lolg:
I checked the flexplate on this 90 engine in the back and sure enough, THE FLEXPLATE has a small weight on it.
It's ALSO KEYED with a rollpin so you can't just mount it any old way like the old ones.
I'd just about bet the 91 is JUST like it... When did the 1 piece rear main seal come out? '87 ??
I WAS WRONG. VetteRacer was RIGHT. (And several other guys out there)
Now PASS that salt and sauce. I'm ready to eat. Wait, where's my dentures ??
:lol: :rofl: :lolg:
Instructor
Joined: Aug 2003
Posts: 163
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From: Glendale Az
Re: [L98]: Internally balanced? (vader86)
Hey Vader, for all intent and purposes, I have run across a couple of 86s with a two piece rear main. Confused, I checked the block casting for the date code and found that in all of GM's wisdom, they did seem to use up the 85 supply on some early 86s. My customer freaked, thought he had a salvage job. :chevy
