Timing tab confusion

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Uncle Bob

Uncle Bob

Shiny paint causes stress.
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I posted this in another thread of mine and it kind of went unnoticed so I wanted to ask again.

What is the purpose of the second bolt-on timing tab on this 77-era 360? (It came on the motor).

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I spent way too much time trying to make a piston stop but eventually realized I can just look in the spark plug hole and see the piston is closer to the head when the balancer is at the cast-in mark, and that it moves further from the head when the timing mark is at the bolt on "peep hole". So the cast in mark is right, as I expected, but WTF reason is there for the other, wrong, timing tab?
 
I believe the peep hole was either on a van, or possibly a truck for ease of sight. In a passenger car, I see no use for it. As far as determining TDC, are you sure the outer ring of the balancer hasn't slipped?
 
I have seen those too?

The peep hole lines up with 10 after. Which is a lot unless one of the advances is in at idle or there are other markings on the front side of the damper

I always thought it had something to do with a possible crank sensor?
 
Yes the damper is OK. I was just confused why this oddball tab is on this car engine. It came out of a 77 Fury.

Vans usually had a peephole in the bellhousing and a mark on that end.
 
Dana67Dart said:
I have seen those too?

The peep hole lines up with 10 after. Which is a lot unless one of the advances is in at idle or there are other markings on the front side of the damper

I always thought it had something to do with a possible crank sensor?
Click to expand...

10 after isn't what anyone wants is it?

There are other marks on the damper at 90* intervals.

ETA I'm going to remove it.
 
Those were for a short-lived timing sensor- it would hook up to the old engine analyzers (there were hand held versions, too), there was a probe you'd slip into that tab along with all the other hookups and you could get timing and advance readings from your ignition system. Most manufacturers had them- I believe Chrysler started using them with the Lean Burn systems, and some of the pre-OBD TBI motors still had them.
Go ahead and toss it.
 
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Is there a slot in the damper somewhere.

That probe input has interesting possibilities.


If you know where TDC is on the damper and when the #1 fires you can calculate the advance, with manifold vacuum and vac advance vacuum, engine temp, throttle position, rpm and O2, imagine the tuning you could do!
 
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