I've checked the service manual but cannot find any details on how to check/set the ignition timing on my car. Is there a sequence to go thru? I've borrowed a timing light and know where #1 cylinder is (bulkhead). Where is the timing plate located where one shines the light? Do you check timing with vac connected or disconnected, or both ways? What readings should I check for?

Perhaps there is a procedure in this forum, but I cannot find one.

 

I have the same questions for my 1975 S2 4.2l T/Strombergs. I know there's idle timing and high rev full advance timing. I know how to accomplish the mechanics of timing; I just don't know what idle and full advance should be. Anyone?

 

Doug to the rescue please!

 

The timing marks are on the LH side of the engine as I recall....but it's been years since I've set timing on the XK type engines.. See the pic; I think it's correct for your car. You'll probably have to use a rag and some solvent to clean everything well enough to see the timing scale

A pinchbolt at the base of the distributor is loosened slightly to allow the distributor to turn to make the adjustment. Rotating the distributor counter-clockwise retards the timing. Clockwise advances the timing

Timing is checked at idle, engine warm, vacuum advance disconnected.

For your '85 the 'base timing' spec is probably 17º BTDC but you can experiment a bit. You might want a little or more or little less depending on driving conditions, fuel octane, etc.

Besides setting the base timing have a helper slowing rev the engine while you operate the timing light. You see see the timing 'advance' up the scale which tells you your centrifugal advance is working. Apply vacuum to the vacuum advance unit and the same thing should happen...the timing should advance.

If you have a timing light with a built-in dial read-out the procedure is a bit different. I'm assuming you have a rudimentary timing light, which is fine.

Hope this 'in a nutshell' info helps. Post back if more questions

Cheers
DD

 

I just did this on my 87, it was tuned to the wrong year (8 deg instead of 17). I had a really hard time finding the marks on the crank, so I slowly bumped it over bit by bit until I found them. Then I went over them with white paint, making sure that it found its way into all the markings. Then wipe off with acetone and a paper towel to leave just the highlighted marks behind.

Now you can hook up your timing light to the battery. If inductive, clip the clamp around the #1 cylinder, which on an XK is actually the rearmost cylinder nearest the firewall (also note the direction the clamp is installed, you should have an arrow pointing towards the spark plug). If your gun isn't inductive just install the pickup between the #1 plug and wire. Remove the distributor advance vacuum hose and plug it up, then turn on the engine.

Check the spec for your year. In an 87 its 17 BTDC at 800 rpm with the advance hose plugged (it says so on the bonnet). Point your gun at the timing indicator on the LH side of the engine as shown in Doug's post to see what your current timing is, and adjust from there. Keep in mind a higher idle with throw the distributor weights out and show more advance.

Loosen the clamping bolt on the distributor, which will require removing the air filter canister. The bolt is on the fender side of the distributor. I unfortunately don't recall the direction of adjustment, but I think CW is more advanced and CCW is retarded. Re-tighten and check timing again until you have the desired setting.

 

Right.

On any car, to retard the timing you turn the distributor in the same direction that the rotor spins. To advance the timing you turn the distributor in the opposite direction that the rotor spins.

Cheers
DD