924Board.org

[bugi924]

1978 924NA - My distributor doesn't seem to be advancing. After I set the timing at idle, the timing only advances about 10 degrees when I rev it.
I think that the vacuum advance is not working. If I put a vacuum pump on either side of the distributor - should each side hold vacuum? Are both sides of the distributor vacuum advance suppose to have vacuum, or does it switch - back and forth?
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1978 924
1987 944
1961 Austin Healey Sprite

[Smoothie]

Yes, both vac line connections at the distributor should hold vacuum.

I'd start with a double-check of the vacuum line routing. The distributor vac connections aren't both vacuum advance - one is advance and the other is retard.. The one nearer the distributor is retard and gets vacuum from downstream of the throttle valve so it's activated when manifold vacuum is high. The further-out connection is vac advance. It gets activated when vacuum upstream of the throttle valve is high - that is when the throttle valve is open.

If all's right with the vac line routing and there are no vacuum leaks, then next thing to check is the centrifugal advance.


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"..it's made in Germany. You know the Germans always make good stuff."


'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

[techfx]

That diagram may be a huge help for me... first place I've seen it so far (didn't see in Haynes).

[ThomasJoseph315]

Get a vacuum gauge and see where the vacuum works at idle and throttle open while the engine is running. Advance should be on the vacuum line with vacuum only during throttle open (right port on the throttle body looking straight on for me) and the retard vac only on the vac port that has vac during idle. ("T"d off the brake booster line for me)

Also make sure your setting your base timing with the vacuum lines attached and in the correct ports.