Just did plugs cap and wires on my 89 v12 and WOW does it run like a top! However, just as you start to crack the throttle open, it has a (very) slight stumble before it picks back up. Any suggestions?

Now part 2: I noticed the old distributor cap had a vaccum line going into it which I plugged off because the new cap didn't have holes drilled in it (and I was too lazy to do it). I assumed it was just to keep it dry inside. Is this assumption correct or am I going to have to go dive back in to fix my own mistake?


*Important tip to Jag new comers...DON'T WORK ON AN XJS WITHOUT HAVING A MAGNET IN YOUR TOOL BOX*

 

Dist cap: that a breather/vent hose to vent fumes out of the distributor. Unless someone has removed it you should see the "other end" ....the fresh air inlet....tie wrapped tp the left fender brace with a small filter attached (looks like a lawnmower fuel filter).

I really wouldn't want to run without one. There are known cases of dist caps blowing apart.


Hesitation: Lots of possibilities but here are a couple of basics which can be elaborated on if you need help...

1) at the rear of each head there's a bellcrank like throttle linkage. Make sure the plastic bushing haven't rotted away. If they have then the throttles won't open in unison
2) clean the throttle bodies and make sure the throttle bladesare set at the proper .002" gap
3) synchronize the throttles using the provided adjustments on the rods. I can suggest a method if you need help
4) make sure you vacuum advance cannisteris working and that the advance mechanism inside the distributor hasn't seized up (rotate the rotors and release...it should snap back "smartly")

If none of this helps.....and its all stuff that needs to be looked at on general principle anyway....we can talk about throttle position sensors

Cheers
DD

 

By the way, what kind of dist cap did you buy? I've never seen one without the nipple for the vent hose. Just curious

Cheers
DD

 

Wow, now that is cool

Not questioning the knowledge on that Doug, I just thought, I would never find stuff that surprised me more than land rover quirks.

 

I think all Brit cars are quirky. Double that for older Jags. Triple it for the XJS V12 !

Depending on your frame of mind that's either "part of the fun" or "a pain in the a** "

Cheers
DD

 

If you can't look at an exploding dist cap as fun then your probably driving the wrong brand of car

 

Perfect. I'm gonna rmeember that. I think you've summed up the entire "old Jag ownership thing" in one simple sentence.

I can see that you're a true "Jag-man"

Cheers
DD

 

Thanks Doug, I checked the vaccum cannister when I had it all apart and I thought its response was a little sluggish. I guess I'll be going back after it later in the winter.