Does anyone know if a Series 3 4.2L U.K spec car should have the vacuum advance on the distributor connected to "ported" or "manifold" vacuum source?
The original timing sticker under the hood states a spec of 6 degrees BTDC at 750 rpm.
I know U.S spec cars have a switch over valve to switch between ported and manifold vacuum but my U.K car doesn't have that.
Also, I just want to confirm the correct procedure for setting up the timing.
I disconnect the vacuum hose and plug it, Check that the rpm is roughly 750rpm,
Set the timing to 6-8 BTDC.
Then if I reconnect the vacuum advance to manifold vacuum the timing advances and rpms increase and I Reset the idle speed to 750rpm.
If i connect to the ported vacuum the rpms dont change because there is no vacuum and therefore no advance.
Does this sound correct?
Thanks

 

My Canadian S3 is set at 8 deg. BTDC at 850 rpm with vac. disconnected and plugged. When vac. is reconnected, there is no change in timing, so the source is Ported.

It's my understanding that Ported vac. is very low at idle (throttle butterfly almost closed), rising as the butterfly is opened. Manifold vac. I believe is basically the opposite.

If the timing advances (along with an idle increase) when you reconnect the source, then I think you are connected to a Manifold vac. source.

Someone set me straight if I'm incorrect please.

 

Mine 1982 model is connected to one of the ports on the throttle body.
Here in Australia the settings are 4 deg BTDC and 800 RPM.
We do not have the switch over valve either.
After doing the timing and idle adjustment there should be no change at idle when you connect the vacuum hose.

 

My car i guess, should be connected to ported then if both of yours are since your timing specs are very close to mine. If anyone with an xj in the UK could confirm that it would be great.
On a side note, its weird how each country had a slightly different timing spec. Canada, Australia and the UK all slightly different with the same hardware setup.

 

I should state that I'm running the Pertronix distributor not the standard one. But, their instructions state that the idle timing should be set to the factory spec, which in my case is 17 deg. BTDC. When I did that, the engine was happy at idle, but practically impossible to start. David, on this forum (from Everyday Jag), recommended my setup be adjusted to 8 deg. BTDC
At this setting it starts (RELUCTANTLY), and idles well - AC on/off, etc. I'm going to retard it to 4 deg. BTDC and see if that improves the starting problem. It's embarrassing to have reluctant start issues in a public parking lot, with people looking on, shaking their heads and muttering to their partners "Jags Honey, I told you so".

 

My car is UK spec (although it is in Thailand) and I am using manifold vacuum. This is the preferred option when available and the US spec cars had to use ported vacuum due to more stringeant emmissions specs. You should get better performance using the manifold vacuum take-off for the distributor.

 

Too much advance, ie initial timing.

 

Arggh, so confusing, some are connected to ported vacuum source and some to manifold vacuum. Andy T. i read your connected to manifold, was that the original factory setup? if anyone knows for sure the factory setup for the u.k and europe please let me know.

 

One more:
USA emissions "experts" want ported vacuum, as you sit for two hours in traffic idling to and from work,

Car manufactures and drivers want manifold vacuum as it best tailors engine for performance and fuel economy during normal driving (cruise control off and lots of acceleration/deceleration in and out of round-abouts)

For USA market: Jaguar added a GM time delayed vacuum valve in to mix to allow ported vacuum when sitting at idle, and moments after the throttle plate open and allows vacuum to distributor through the GM valve, the GM valve closes ported vacuum off and allows distributor to be connected directly to manifold vacuum. When car stops at red light, after a few moments you are back to ported vacuum.

A UK Jaguar should best be connected to manifold Vacuum...If you look carefully at the literature there are different vacuum advance part numbers for US and UK distributors. Again use the UK part numbers for best performance.
Hope this helps
Rgds
David