Author Topic: Balancer Question  (Read 1187 times)

SoupMan

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Balancer Question
« on: August 20, 2022, 11:05:33 PM »
How likely is it for a balancer to slip on a Pontiac 455?

The balancer my 76 455 block the original.

How can I find TDC so I can re-mark the balancer to confirm it hasn't slipped?

aussieta

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Re: Balancer Question
« Reply #1 on: August 21, 2022, 12:32:11 AM »
you use a piston stop
basically a long bolt that matches the spark plug thread
https://www.amazon.com/s?k=piston+stop+14mm&crid=2JDNOMG3TD0I1&sprefix=piston+stop+14mm%2Caps%2C260&ref=nb_sb_noss_1
remove all spark plugs
screw piston stop into number 1
with a socket on crank bolt, rotate engine gently clockwise
when piston touches piston stop, mark balancer
then gently rotate counter clockwise
when piston touches piston stop, mark balancer
tdc is halfway between your marks
1978 Y84 W72 WS6
A Camaro looks like it could kick your ass.
A Trans Am looks like it's coming over to do it

SoupMan

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Re: Balancer Question
« Reply #2 on: August 21, 2022, 02:08:42 PM »
Thanks. I'll do exactly that and see where that lands me.

tajoe

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Re: Balancer Question
« Reply #3 on: August 21, 2022, 04:39:51 PM »
What makes you thing the balancer has slipped? Are you having any issues?
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SoupMan

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Re: Balancer Question
« Reply #4 on: August 21, 2022, 06:35:38 PM »
In another thread about setting timing tables I've been trying to find the best tune for my Sniper / Hyper Spark. My reading plus information from this forum leads me to believe my 455 with XE274 cam and 6x-8 heads can handle 32 degrees of timing total advance. Using 91 octane.

Prior to the Hyperspark I was running 26 total advance and motor was ok. I figured I have 6 to 8 degrees to gain so started adding timing. I however "appear" to be pinging. To confirm this I dropped the timing from 32 to 26 in the EFI and BOOM, the concerning sound is gone. I was also hearing a knock sound at idle at 20 degrees of timing. I dropped it to 16 and it's gone.

Now this could all still be in my head but I'd rather be safe than sorry.

Re: Balancer Question
« Reply #4 on: August 21, 2022, 06:35:38 PM »

tajoe

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Re: Balancer Question
« Reply #5 on: August 21, 2022, 07:31:22 PM »
You're idling at 20°? Are you talking "including" vacuum advance? You don't mean your initial timing is 20°, with the vacuum canister plugged.
"You can sell an old man a young mans car,
but you can't sell a young man an old mans car"
                                       Bunkie Knudsen
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SoupMan

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Re: Balancer Question
« Reply #6 on: August 21, 2022, 09:20:10 PM »
Yes, includes vacuum.

It's the MAP for the Sniper EFI.

For reference this is the thread. http://www.transamcountry.com/community/index.php?topic=84311.0

I'm honestly just making sure everything is good before I move to the next step.
« Last Edit: August 21, 2022, 09:21:56 PM by SoupMan »

FormTA

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Re: Balancer Question
« Reply #7 on: August 22, 2022, 01:18:11 AM »
You could buy one of those cheap wifi cameras from Amazon and fish it into the spark plug hole to confirm you are at TDC. I really don't like those piston stop thingys. You will find other uses for the mini camera too.

https://www.amazon.com/NIDAGE-Automotive-Inspection-Semi-Rigid-Smartphones/dp/B07C9C6P5D/ref=mp_s_a_1_4?crid=K05P7Y5ADP89&keywords=camera+on+a+wire&qid=1661152624&sprefix=camera+on+a+%2Caps%2C121&sr=8-4
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nUcLeArEnVoY

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Re: Balancer Question
« Reply #8 on: August 22, 2022, 06:51:20 AM »
You're idling at 20°? Are you talking "including" vacuum advance? You don't mean your initial timing is 20°, with the vacuum canister plugged.

Not too unheard of, especially for big cammed cars. Stock base timing for late 70's 400's was 17-18.
1979 Trans Am 400/4-Speed W72/WS6 - Starlight Black Hardtop

ryeguy2006a

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Re: Balancer Question
« Reply #9 on: August 22, 2022, 09:13:30 AM »
If you are using the original balancer, I'd say that there is a good chance it has has slipped.

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tajoe

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Re: Balancer Question
« Reply #10 on: August 22, 2022, 02:35:43 PM »
The piston stop method is more accurate, because when the rod goes over TDC, there is a dwell period where the piston isn't moving but the crank is. And the amount could vary between rod lengths, or strokes. You won't see that with a camera.
You're idling at 20°? Are you talking "including" vacuum advance? You don't mean your initial timing is 20°, with the vacuum canister plugged.

Not too unheard of, especially for big cammed cars. Stock base timing for late 70's 400's was 17-18.
20° of initial is a ton by todays standards, and back when gas was "good" (leaded), most dist. curves were around 12 0r 13, which equates to 24-26 crank, and with 10-12° of initial advance was a decent total timing of 36-38. Those were good numbers for most street strip engs, with either open, or closed chambered heads.
If anyone was running 20° initial timing, then in order to have those total advance numbers, the dist. would only have about 7-8°, which is a pretty lazy curve. But if we're talkin late 70s, it wouldn't surprise me, emissions tuning being as ridiculous as they were. And I guarantee, they weren't programming those cars, for 36° of total advance.
"You can sell an old man a young mans car,
but you can't sell a young man an old mans car"
                                       Bunkie Knudsen
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djustice

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Re: Balancer Question
« Reply #11 on: August 24, 2022, 07:24:41 AM »
It can slip the elastometer and be off, OR it can crack in the keyway and be off, but still rotate with no wobble!
Mine cracked, and only thing that was noticable was exessive idle timing, when i pulled the balancer i found this:
1973 Firebird formula 400 W/YC code 455+60 over (73 casting)
Butler CNC 315+ cfm heads, hyperfuel efi gastank, scorpion 1.5 Roller rockers, holley sniper efi, hurricane singleplane intake, Headman 28150 headers 1 3/4" primary, Pypes SGF11R exhaust, Rollercam 230/236 @112 LSA 2 row alu radiator w/twin 12" Spal fans. Yukon duragrip posi w/3.42 gears.

SoupMan

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Re: Balancer Question
« Reply #12 on: August 24, 2022, 01:16:27 PM »
Holy crap.

What did you replace it with?  If mine is gone I'm leaning on a ATI Super Damper.

tajoe

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Re: Balancer Question
« Reply #13 on: August 24, 2022, 02:09:45 PM »
Yuk. that looks pretty nasty, DJ. Good thing Pontiac uses that nice big bolt to hold it all together.
"You can sell an old man a young mans car,
but you can't sell a young man an old mans car"
                                       Bunkie Knudsen
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djustice

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Re: Balancer Question
« Reply #14 on: August 24, 2022, 03:47:03 PM »
I count myself super lucky to have caught it in time before major damange. I replaced it with powerbond SFI approved balancer, from bop engeneering: https://bopengineering.com/A_Pontiac_Engine_Crankshaft_Related.shtml
1973 Firebird formula 400 W/YC code 455+60 over (73 casting)
Butler CNC 315+ cfm heads, hyperfuel efi gastank, scorpion 1.5 Roller rockers, holley sniper efi, hurricane singleplane intake, Headman 28150 headers 1 3/4" primary, Pypes SGF11R exhaust, Rollercam 230/236 @112 LSA 2 row alu radiator w/twin 12" Spal fans. Yukon duragrip posi w/3.42 gears.

Re: Balancer Question
« Reply #14 on: August 24, 2022, 03:47:03 PM »

nUcLeArEnVoY

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Re: Balancer Question
« Reply #15 on: August 27, 2022, 09:43:55 AM »
The piston stop method is more accurate, because when the rod goes over TDC, there is a dwell period where the piston isn't moving but the crank is. And the amount could vary between rod lengths, or strokes. You won't see that with a camera.
You're idling at 20°? Are you talking "including" vacuum advance? You don't mean your initial timing is 20°, with the vacuum canister plugged.

Not too unheard of, especially for big cammed cars. Stock base timing for late 70's 400's was 17-18.
20° of initial is a ton by todays standards, and back when gas was "good" (leaded), most dist. curves were around 12 0r 13, which equates to 24-26 crank, and with 10-12° of initial advance was a decent total timing of 36-38. Those were good numbers for most street strip engs, with either open, or closed chambered heads.
If anyone was running 20° initial timing, then in order to have those total advance numbers, the dist. would only have about 7-8°, which is a pretty lazy curve. But if we're talkin late 70s, it wouldn't surprise me, emissions tuning being as ridiculous as they were. And I guarantee, they weren't programming those cars, for 36° of total advance.

Yeah, they did have very slow mechanical advance curves with very stiff springs - you'd have to go near redline to get the full 18 or so degrees, by which point vacuum advance is probably well out of the equation. And the driveability was mostly aided by vacuum advance cans that added in a ton of timing early on. For instance, the '78 and '79 W72 400 vacuum advance threw in 25 degrees of timing all in by 11-12" of vac.
1979 Trans Am 400/4-Speed W72/WS6 - Starlight Black Hardtop

nUcLeArEnVoY

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Re: Balancer Question
« Reply #16 on: August 27, 2022, 09:45:03 AM »
It can slip the elastometer and be off, OR it can crack in the keyway and be off, but still rotate with no wobble!
Mine cracked, and only thing that was noticable was exessive idle timing, when i pulled the balancer i found this:

Yikes! That's scary. What'd you replace it with?

Has anybody used the PowerBond stock replacement balancers? Are they any good?
1979 Trans Am 400/4-Speed W72/WS6 - Starlight Black Hardtop

djustice

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Re: Balancer Question
« Reply #17 on: August 30, 2022, 07:14:19 AM »
the ATI superdamper looks real trick and has a good reputation as a race damper. but if you are running stock pulleys it migth require you to order/make your own pulleys as some webistes state:
" Does not accept stock Pulleys."

The good thing about the powerbond units is that my stock pulleys bolted rigth on and the center indexing lip was a perfect fit. so no extra unwanted suprises.
1973 Firebird formula 400 W/YC code 455+60 over (73 casting)
Butler CNC 315+ cfm heads, hyperfuel efi gastank, scorpion 1.5 Roller rockers, holley sniper efi, hurricane singleplane intake, Headman 28150 headers 1 3/4" primary, Pypes SGF11R exhaust, Rollercam 230/236 @112 LSA 2 row alu radiator w/twin 12" Spal fans. Yukon duragrip posi w/3.42 gears.

Re: Balancer Question
« Reply #17 on: August 30, 2022, 07:14:19 AM »
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