Friday, September 27, 2019

Changing the 12 sparkplugs in my XJS, Act Three.

I picked up a few things that I thought might help.

I left off last week after removing all the sparkplugs.

There was a little bit of drama involved in just getting the replacement plugs. This was an engine that was pretty rare in the U.S. when it was new, now twenty five years later even the plugs are not that common. It had Bosch Super R6 665 plugs  installed and they had worked fine until this last bout of unpleasantness. I figured that I wold just replace them with the same type. My local "good" auto parts store didn't have them in stock. They would have to order them and could have them by the next day. Great, I was dedicating the entire weekend to getting this job done. I tried one of my local chain auto stores and again they didn't have them in stock again but "we can order them for you."

Well, if they're going to be ordered than I'd rather give my business to the "good" shop. I should have pulled one of the easy plugs right away and taken it to the store with me. Eventually they found an NGK equivalent BKR6E-11. And they had twelve in stock. The H.E. V12 has tapered spark plug seats but the Bosch plugs that I pulled out were gasket seal plugs. Well, if they had worked okay to this point than I guess they would still do.

The moral of the story is, source the plugs before you start the job. It could eliminate a long delay.

Who would have thought that gapping and installing twelve spark plugs could take so much time?

That little "trouble light" has really come in handy. My eyesight is not that bad, but I really can't make out precise detail in low light situations. I had a couple of lights set up under the hood but It helps to be able to position a light source right where you're working.

We are living in the "Golden Age" of plentiful, extremely bright, inexpensive lights. Everything is halogen or LED and they come in all sizes and kinds of configurations. 

Luckily you will never have to manage with a 60 watt droplight and a two D cell flashlight!


That light is quite bright
 and easy to position where it's needed.

I managed to remove the two sparkplugs that were located alongside the base of the throttle tower using a universal adapter and a "wobbly" extension. I was very concerned about re-installing the plugs because of the tight fit. I was fearful of cross threading them. The plugs located under that silver tube weren't going to be easy to re-install either.

I decided to remove the throttle tower. It is held down by four bolts. The two front bolts are easily accessible, the rear are almost impossible to reach using conventional sockets and extensions. That's where that crow's foot wrench set came in handy. I had to run down to Harbor Freight to buy the SAE set to match the Metric set that I already had. I'm removing the two rear bolts in the picture above.


Opening up these bolt holes into slots will help speed things up.

I'd been referencing Kirby Palm's book for tips. One of the contributors mentioned cutting slots in the rear bolt holes so that the bolts could be started in the block and the base slipped under the heads of the bolts. It sounded like a good idea. I just added some bigger washers under the bolts and taped them to the head of the bolt to hold them up while I installed the tower. It worked out well. In the future I think that I could remove the coil first, then disconnect the throttle rods from the throttle bodies then loosen the bolts holding the tower, and could just shift the tower around a bit to remove and install the plugs.

I could probably replace the rear four spark plugs easily, then re-install the throttle tower.

That little spark plug tool I bought was worthless. It was poorly made and just too short to be of use. Oh well.


Those crowfoot wrenches do have a few applications.

This picture was actually taken while I was removing the tower, note the intact bolt hole area. It's just a clear shot showing how the crow's foot wrench was used.

Be sure to check if the spark advance springs are working properly, clean and lubricate as needed. Read Kirby's book!

All the plugs were installed, then the distributor cap was placed into position. I left it loose so that I could shift it from side to side or front to back to make it easier to reattached the plug caps. I found it easier to remove the coil from the front of the throttle capstan plate before I installed the assembly. Then I added the coil.

Reattaching all the hoses and wires calls for a lot of caution. The coil and amplifier wires are likely to be very crispy with cracked and missing insulation. There is a coax wire from the amplifier to the ECU that will likely be fragile and easily damaged. I ended up peeling back the wrapping and re-insulating the inner wire, then wrapping up the whole thing in electrical tape to secure and protect the connection. You would not believe how thin that inner wire is! It's just sitting out there next to a hot water manifold that had reduced the connector housing to the constitution of a soda cracker! I plan on reinforcing this connection and insulating it from the heat. If this wire breaks, that motor is dead in the water. I broke one amplifier wire and had to splice in a new section of wire and connector. I plan on redoing this whole area of wiring in the future.

Okay, it looks like everything is reinstalled and hooked up. I had placed the battery on the tender for several days and it was up to full charge. Nothing left to do but crank it up, Right?

No guts no Glory!

Total time invested Today, 6 hours and 45 minutes.

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