The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1967 - 1972 Chevrolet & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 04-26-2007, 01:02 AM   #1
Rat72
Registered User
 
Rat72's Avatar
 
Join Date: Sep 2006
Location: Portland
Posts: 135
BB Harmonic Balancer Timing Pointer Issues

I've been strugling with a bunch of issues. The 454 that came in my truck had a flat cam lobe which obviously caused lots of issues. The other issue I had when it ran was that the timing would not let the motor even run until I got it to 16 degrees. So I installed a new cam and when I brought the motor up to TDC, the timing mark on the balancer points at .... 16 degrees. I've not done this before but I assume it should point at 0 (TDC).

So, are there different balancers for the different years of 454? The balancer I have looks like the original one and looking from the front, the timing channel (line) is about 8 degrees counterclockwise from the keyway.

Are there different pointers for the different years? The pointer I have is a cheesy chrome aftermarket unit and 0 degrees is very close to where the timing cover raises out to clear the gears.

Or am I just mistaken regarding the timing pinter lining up with the balance line at TDC?

Any feedback would be appreciated.

Thanks,
Whit
Rat72 is offline   Reply With Quote
Old 04-26-2007, 01:05 AM   #2
RACINJASON22
GEARHEAD
 
RACINJASON22's Avatar
 
Join Date: Jan 2007
Location: CENTRAL,PA
Posts: 2,284
Re: BB Harmonic Balancer Timing Pointer Issues

I'm not real sure on BBC's but, I would almost bet there are different one's as is the case with SBC's

BTW Do ya maybe want this thread moved to engine and drivetrain forum???? You will get more answers there.
__________________
72 SWB 2WD MY PROJECT
72 LWB 4X4 FUTURE PROJECT

SUBSCRIBE HEREBOARD VENDORS HERE

NORWOOD MEET SURVIVOR!

Last edited by RACINJASON22; 04-26-2007 at 01:06 AM.
RACINJASON22 is offline   Reply With Quote
Old 04-26-2007, 09:03 AM   #3
OLDCHEV4X4
Registered User
 
OLDCHEV4X4's Avatar
 
Join Date: Apr 2000
Location: Chester County PA, USA
Posts: 1,228
Re: BB Harmonic Balancer Timing Pointer Issues

I do believe when the piston is at TDC the timing mark should be on 0.
If its not mabey the outer ring on the balancer has sliped.
Or the timing chain is real slopy or has jumped a tooth.
But since you changed the cam, i assume you put a new timing chain on. So thats probley not it.
I would bring it up to TDC and put a mark on the balancer at 0 and tune from there. Mabey get a new balancer.
Just some food for thought...
__________________
72 k/10 short wideside
72 k/5 Blazer
72 K/5 Blazer - obstacle course racer
72 custom/10 8' bed
70 K/5 Blazer
67 C-30 GMC Flat bed
86 GMC K2500 Plow Truck
85 GMC K3500
84 M1008
85 M1008
77 G30 Motor Home
72 Sears 12hp Tractor
Glenmoore, Pennsylvania
OLDCHEV4X4 is offline   Reply With Quote
Old 04-26-2007, 10:25 AM   #4
cooters
Senior Member
 
Join Date: Oct 2006
Location: Edmonton Alberta
Posts: 458
Re: BB Harmonic Balancer Timing Pointer Issues

big blocks are common for the balancer ring to rotate and the mark is out, thats why i powertime for the best result
cooters is offline   Reply With Quote
Old 04-26-2007, 10:42 AM   #5
fosheec
Registered User
 
fosheec's Avatar
 
Join Date: Oct 2006
Location: Cedarville, OH
Posts: 61
Re: BB Harmonic Balancer Timing Pointer Issues

When I had my 402 I just timed it by ear. Once I got it where it ran the best, I used the timing light. The mark on my balancer would come up around the 12 o'clock area, with my timing pointer in the 2 to 230 region. I think it is safe to say it had slipped a little.
__________________
Caleb
fosheec is offline   Reply With Quote
Old 04-26-2007, 11:52 AM   #6
Rat72
Registered User
 
Rat72's Avatar
 
Join Date: Sep 2006
Location: Portland
Posts: 135
Re: BB Harmonic Balancer Timing Pointer Issues

Regarding the outer ring slipping on the crank. Should the keyway in the crank line up exactly with the timing line on the outer ring?

And how does an aftermarket balancer work. Are the original balancers all balanced the same or are they balanced differently? I assume that GM wouldn't do real assembly balance but that they might match parts based on some rough weight calculations.

Thanks,
Whit
Rat72 is offline   Reply With Quote
Old 04-26-2007, 12:35 PM   #7
jhow66
Registered User
 
jhow66's Avatar
 
Join Date: Jun 2002
Location: Knoxville Tenn.
Posts: 3,058
Re: BB Harmonic Balancer Timing Pointer Issues

Here is an easy way to test to see if marks are right. Line up the bal. mark with 0 on timing tab. Remove #1 plug. Put a straw in plug hole until it touches piston. Turn engine (by hand). If straw starts to go down your marks are right.
__________________
56 Chevy Bel-Air 2dr. HT (purchased new)
71 Chevy Cheyenne SWB PU (502HO)
65 GMC short bed step--work in progress and my gofer
jhow66 is offline   Reply With Quote
Old 04-26-2007, 12:54 PM   #8
Rat72
Registered User
 
Rat72's Avatar
 
Join Date: Sep 2006
Location: Portland
Posts: 135
Re: BB Harmonic Balancer Timing Pointer Issues

Quote:
Originally Posted by jhow66 View Post
Here is an easy way to test to see if marks are right. Line up the bal. mark with 0 on timing tab. Remove #1 plug. Put a straw in plug hole until it touches piston. Turn engine (by hand). If straw starts to go down your marks are right.
The pistion starts going down when the timing line is at 16 degrees before tdc. The piston has gone down quite a ways by the time it reaches 0. I'm very confident that I'm at TDC. I just can't figure out why the timing line is not lining up. Either the balancer has rotated or the pointer is incorrect for the application. I'm leaning towards it being the balancer but the rubber looks fine between the ring and the unit. And I've seen pictures of balancers that have the same timing line to keyway alignment. Mine is about 8 degrees counter clockwise from the keyway. To line up correctly with the pointer it needs to be about 8 degress clockwise.

Thanks,
Whit
Rat72 is offline   Reply With Quote
Old 04-26-2007, 10:24 PM   #9
jhow66
Registered User
 
jhow66's Avatar
 
Join Date: Jun 2002
Location: Knoxville Tenn.
Posts: 3,058
Re: BB Harmonic Balancer Timing Pointer Issues

A foolproof way is to do this:
1--remove #1 plug (best to remove all so motor will turn easy)
2-- make or buy a piston stop
3--turn motor SLOWLY until it hits stop
4--make mark on balancer at 0 mark on tab
5--turn motor back the other way until it hits stop again (SLOWLY)
6--repeat #4
7--1/2 way between these marks will be the exact TDC for #1
__________________
56 Chevy Bel-Air 2dr. HT (purchased new)
71 Chevy Cheyenne SWB PU (502HO)
65 GMC short bed step--work in progress and my gofer
jhow66 is offline   Reply With Quote
Old 04-26-2007, 10:37 PM   #10
rage'nrat638
Account Suspended
 
rage'nrat638's Avatar
 
Join Date: Mar 2003
Location: ** THE FALL GUY **CHICAGO IL
Posts: 5,883
Re: BB Harmonic Balancer Timing Pointer Issues

has the bottom timing gear been installed in the stock key slot
most after market gear sets have atleast 3 keyway slots
some have more.

adv
reg
retarted
?
rage'nrat638 is offline   Reply With Quote
Old 04-29-2007, 08:02 PM   #11
Rat72
Registered User
 
Rat72's Avatar
 
Join Date: Sep 2006
Location: Portland
Posts: 135
Re: BB Harmonic Balancer Timing Pointer Issues

Quote:
Originally Posted by rage'nrat638 View Post
has the bottom timing gear been installed in the stock key slot
most after market gear sets have atleast 3 keyway slots
some have more.

adv
reg
retarted
?
Good thinking. The top gear has 9 but that is irrelevant to finding TDC. Unfortunately the bottom gear has only keyway.

Thanks,
Whit
Rat72 is offline   Reply With Quote
Reply

Bookmarks


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 10:55 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com