Timing Mark on balancer

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Nov 14, 2022 | 08:17 AM

Lark327

Thread Starter

Instructor

Joined: Nov 2014

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From: Wilmington, NC

Timing Mark on balancer

I want to confirm the timing on my 72, all stock base 350. There is a timing mark on the damper. Is that mark TDC? or would it indicate the factory setting which for this engine, which I believe is 8 degrees BTDC? Thanks

Nov 14, 2022 | 09:13 AM

Douglas Mariani

GM Cert Corvette Tech

Joined: Apr 2008

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From: Anaheim Hills California

The long groove on the harmonic balance is top dead center of the crank. There should be a plate attached to the timing cover which will give you your degree indications to advance or retard the timing.

Nov 14, 2022 | 09:56 AM

Mr D.

Team Owner

Joined: Mar 2002

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From: Huntsville AL

Something similar to this

Nov 14, 2022 | 10:05 AM

barkingrats

1967 Pedal Car Champion

Joined: Mar 2020

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From: US-PNW

Quote:

Originally Posted by Lark327

Quote:

Originally Posted by Douglas Mariani

When the balancer line is right under the -0- mark of the timing tab, you are either TDC on #1 or #6. Without testing for compression, observing valve movement, or hooking a timing light on the spark wires on either cylinder you don't know which TDC you're looking at. When using a timing light, that -0- mark is neutral in that the spark is happening at TDC. Your base timing should be anywhere from 4° to 12° before TDC. (For our Chevrolets, the marks above the -0- are advanced, below -0- are retarded - the motor spins clockwise when viewed from the front.) As seen above, most (all?) factory timing tabs are in 2° increments.

Nov 14, 2022 | 03:16 PM

Lark327

Thread Starter

Instructor

Joined: Nov 2014

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From: Wilmington, NC

Great response. Thanks.

Nov 14, 2022 | 10:59 PM

barkingrats

1967 Pedal Car Champion

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From: US-PNW

Another consideration with the harmonic balancer and the engraved line is that the outer ring of the balancer can shift on the hub due to deteriorated rubber between the two parts. It becomes evident that something is amiss with the balancer's integrity when you can't set the timing without getting excessive pinging. The only way the engine will run is by retarding the timing (which is almost never done for typical street engines). Examine the rubber ring to make sure it isn't missing pieces or is swelled and gooey – the pic Mr.D posted shows a pretty questionable ring.

Nov 15, 2022 | 06:54 AM

Chuck72

Le Mans Master

Joined: Nov 2004

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From: Tampa, Fl.

First, get this:

Proform 66792 Top Dead Center Locater https://a.co/d/aGkDTZz

Nov 15, 2022 | 09:50 AM

barkingrats

1967 Pedal Car Champion

Joined: Mar 2020

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From: US-PNW

Quote:

Originally Posted by 67:72

Another consideration with the harmonic balancer and the engraved line is that the outer ring of the balancer can shift on the hub due to deteriorated rubber between the two parts. ~~It becomes evident that something is amiss with the balancer's integrity when you can't set the timing without getting excessive pinging. The only way the engine will run is by retarding the timing~~ (which is almost never done for typical street engines). Examine the rubber ring to make sure it isn't missing pieces or is swelled and gooey – the pic Mr.D posted shows a pretty questionable ring.

Awoke this morning thinking about my comment and wanted to fix it. If the ring slips on the hub, it appears that the engine's timed is too far advanced, so the natural thing to do is retard it so the mark aligns with whatever tab degree mark is desired. Now the newly set actual retarded timing is making the spark happen closer to or after TDC which isn't good for performance, efficiency, or driveability.