Distributor notch mystery

[pippo]

Hi People,

First time here!! lets start with a mystery: I have a 87 sunbird, GT non turbo. The distributor has 2 deep engraved notches, one on the outer section (the one you rotate to time the car) and one on the base such that if you rotate the outer you can match up the notches up to meet. Why did GM do this? Whats the purpose of these notches? to set the timing and leave it there?

Even though my "sticker" stuck on ther hood gives instructions to time the car at 8 deg BTDC, there is NO scale mounted on top of the crankshaft pullley. Why, if sticker says to set timing based on 8 deg BTDC if theres no timing scale?
Did some mechanic years ago, when changing the timing belt and water pump find it annoying and removed it, and never put it back?

Thanks

 

[92 Sunbird LE]

Timing tab is part of the plastic timing belt cover, if it been broken off, you have to find another in a wrecking yard. ( no new ones are available)

that might explain the marks if its missing .................oldschool dis adjustment, I used to do the same on my cars back in the day........normal and advanced timing

Doug in P.R.

 

[92 Sunbird LE]

Pics..........( borrowed from "Superbee" on the Jbody Forums)


Doug in P.R.

 

[pippo]

Pics..........( borrowed from "Superbee" on the Jbody Forums)


Doug in P.R.

Thanks, Doug. Good to know. Handy picture showing the tab stuck onto the plastic timing cover. But just what do you mean by "old school timing", Id like to at least be aware of that just in case......

______________________________

 

[pippo]

But Doug, what about the notches? What were they intended for? Have any on your sunbird?

Thanks

 

[92 Sunbird LE]

Oldschool: put notches or paint marks on the dis and manifold were you want the stock timing to be or advanced timing to be. quick way to set it at the racetrack for different octane fuels.

My 92 has no way to set timing , its all computerized with no dis and gets it firing timing from a reluctor wheel on the crankshaft and crank position sensor mounted on the side of the engine block, its same as the later 2.0 Turbo models, still has a cover on the drivers side head were a distributor would go.

I would in your case, aline the marks and check it with a timing light to see if its dead on.

I know on OBD1 equipped cars, there is not much timing you can put in manully since the computer takes over anyway. Only way to advance it ( timing ) reallly is with a new reprogramed chip aka Prom or with the Moates system that wires you up directly to the chips port with a laptop.

Doug in P.R.

 

[pippo]

Oldschool: put notches or paint marks on the dis and manifold were you want the stock timing to be or advanced timing to be. quick way to set it at the racetrack for different octane fuels.

My 92 has no way to set timing , its all computerized with no dis and gets it firing timing from a reluctor wheel on the crankshaft and crank position sensor mounted on the side of the engine block, its same as the later 2.0 Turbo models, still has a cover on the drivers side head were a distributor would go.

I would in your case, aline the marks and check it with a timing light to see if its dead on.

I know on OBD1 equipped cars, there is not much timing you can put in manully since the computer takes over anyway. Only way to advance it ( timing ) reallly is with a new reprogramed chip aka Prom or with the Moates system that wires you up directly to the chips port with a laptop.

Doug in P.R.

Thanks, Doug. Guess I have not much to wory about, car runs OK anyway.....except for rough idle.