Euro intercooled 3.3L timing

[Speedy Squirrel]

The post about safe timing got me to thinking about the Euro spec engine timing. The '78 Euro motor is the least encumbered by emissions. I believe they did not even have an air pump until 1983.

Here are the charts from the manual:



The spec for setting the ignition is 29 to 31 degrees BTDC at 4000 RPM. The charts are in distributor degrees, and distributor RPM, which I presume is half the crank degrees and crank RPM. It does not matter if the single pot hose is connected or disconnected, since the amount of throttle required to reach 4000 RPM and no load will have cut off the distributor ported vacuum (distributor vacuum is zero).

The centrifugal advance gives a maximum tolerance of about 6 cam degrees (12 crank degrees) at 2000 distributor RPM (4000 crank RPM).

So, does that mean the base crank timing is around 20 BTDC (crank degrees) at idle (roughly 1000 RPM Crank, 500 RPM distributor)? That seems to make sense, since the maximum vacuum retard is 22 degrees crank (11 degrees distributor) at idle vacuum (somewhere between 200 and 250 Torr).

The check at idle with the hose connected is 0 BTDC + or - 2 (crank). At idle the 20 degrees vacuum retard counters the 20 degrees advance of the base timing, as there is no centrifugal advance at 1000 RPM (crank). Does that make sense?

[Mr9146]

Originally Posted by Speedy Squirrel

The post about safe timing got me to thinking about the Euro spec engine timing. The '78 Euro motor is the least encumbered by emissions. I believe they did not even have an air pump until 1983.

Here are the charts from the manual:



The spec for setting the ignition is 29 to 31 degrees BTDC at 4000 RPM. The charts are in distributor degrees, and distributor RPM, which I presume is half the crank degrees and crank RPM. It does not matter if the single pot hose is connected or disconnected, since the amount of throttle required to reach 4000 RPM and no load will have cut off the distributor ported vacuum (distributor vacuum is zero).

The centrifugal advance gives a maximum tolerance of about 6 cam degrees (12 crank degrees) at 2000 distributor RPM (4000 crank RPM).

So, does that mean the base crank timing is around 20 BTDC (crank degrees) at idle (roughly 1000 RPM Crank, 500 RPM distributor)? That seems to make sense, since the maximum vacuum retard is 22 degrees crank (11 degrees distributor) at idle vacuum (somewhere between 200 and 250 Torr).

The check at idle with the hose connected is 0 BTDC + or - 2 (crank). At idle the 20 degrees vacuum retard counters the 20 degrees advance of the base timing, as there is no centrifugal advance at 1000 RPM (crank). Does that make sense?

Wat?

[Speedy Squirrel]

Hoping one of our Euro associates will let me know what the crank timing is with the vacuum hose to the distributor blocked. If I am understanding the manual correctly, the base timing is 18 - 20 advanced. The vacuum canister takes that out when connected, so the crank timing is near 0 when connected. As you open the throttle the vacuum goes to zero, and the base timing comes back in, plus the centrifugal advance comes in with Increasing RPM. It adds about 11, so you could (should?) be running as high as 31 under boost.

I am resetting a US grey market car to return to the Fatherland, and I want to make sure it is correct.

[Mr9146]

You're overcomplicating things.

I'll check the manual for you tomorrow...

[RarlyL8]

Unplug the single pot vac and set at 29 degrees @ 4000rpm. Done.

[Mr9146]

Brian beat me to it (been working like a dog since 6:30am).

[Speedy Squirrel]

Thanks guys. Got the same answer from Germany too. Apparently, it is not even possible to set the base timing at idle (1000 RPM), as the engine will not idle that low with the amount of base timing it is supposed to have, and with the vacuum can disconnected.