Here’s a howdy do…
I have 5 old side entry distributor caps, one with a variation important to know about.
Here are two Lucas and one with no brand name.
Notice the Lucas on the left and the unmarked in the middle have the coil port in line with the side clips. The Lucas on the right has the coil port advanced at a 60 degree angle relative to the side clips.
The danger is that someone setting out to change his cap, will draw a picture of the cap with the 6 plug wires numbered in relation to the coil wire, and put the wires on the new cap in the same order in relation to the coil wire as they came off the old cap, while getting them nicely fitted in parallel in the oval rubber clips. Then will find that his car won’t start afterwards. It may take him a couple hours to figure out that the two caps have the coil wires at different angles.
Guess who made that mistake.
Hi Rob, thanks for pointing out that variation. Surely pattern copy on transferring wires is second nature and I would fall in the same difficulty. Perhaps the variation was made to accommodate vacuum advance position on some cars.
It looks like Rob is referring to MkV caps .the Sscap for the DUH6A is quite a bit bigger,
But speaking of later changes, on the Ss originally the earthing was via the 2 screws that held the bakelite base.
This was unreliable as one of our SS Register members found out on a club run. Later replacement parts had a separate earth terminal on the side. Worth the effort if you can find one.
Hi Rob,
I see from an earlier post that your Mark V has “the distributor turned at a different angle from what it is on an XK engine”.
Rightly or wrongly I am reverting to originality with XK 120 679265 and have obtained a side entry cap.
Offering it up to the distributor body results in the 6 leads coming out at an angle which makes them point ridiculously close to the engine block and it would be highly desirable to rotate the whole distributor anticlockwise to have the leads pointing out parallel with the block to keep them clear.
Do you see any problem with making this adjustment?
I am presuming that the timing should be unaffected if the rotor arm stays in the same relationship with the cap contacts.
Simon
There is a discussion on setting the rotor angle in the XK forum archives.
The distributor shaft gear has 20 teeth so there are 20 ways to set it, but the manual describes the way the factory setting is achieved.
If you are too far along to change this, you can turn the distributor 60 degrees and move the wires around accordingly.
The same principle would apply to the pushrod engines, setting the distributor gear into the camshaft gear so the rotor and distributor end up in a convenient angle.
Hmm, DIP is the lever you flip when there is a low place in the road or you need to put one in your dip dee dip dee dip, so ADVANCE must mean you flip it to make the car go forward with your boogedy boogedy shoes.
Yes it is. I have four, as the V12 E has four carbs, but I think it was bit more difficult to use on it as well as the MKV because of the angle of the spark plugs. On the XK engine however, with triple SU’s I think it is a good way to check that the flames go yellow at the same time and same volume to see that the mixture gets rich when the throttle is opened. But it’s not very accurate for adjusting the AFR (air fuel ratio) like a lambda is. I have been tempted to add bungs for lambdas on the V12 to get better / more accurate readings in a dyno for the whole power range, I got a spare exhaust section after the downpipes for that purpose, as then I could also have lambdas fitted and record data on the road.
I am pretty sure the air flow to the carbs is very good through the original air filter trumpets.
Many race cars of the era confirm that the tubes work well at high speeds. Perhaps not when a car is standing still in a dyno, but when the car is going forward faster than 130mph I am sure the air flow is pretty good.
In the MKV I know there are MANY problems with the airflow and cooling of inlet air, but IMO these cars do not need to go so fast. 120km/h (75mph) is enough for me and the DHC, and it also happens to be the max speed allowed in Finland on any highway. I am taking the XJ6C (MOD) to Germany this year, but she will probably not do 200km/h (124mph) although I may be tempted to try (Euro spec car with 2 x 2" HS8 SU’s). The V12 did 229km/h in 2018 (142+mph according to the GPS) without much effort.
I have four, as the V12 E has four carbs, but I think it was bit more difficult to use on it as well as the MKV because of the angle of the spark plugs. On the XK engine however, with triple SU’s I think it is a good way to check that the flames go yellow at the same time and same volume to see that the mixture gets rich when the throttle is opened. But it’s not very accurate for adjusting the AFR (air fuel ratio) like a lambda is. I have been tempted to add bungs for lambdas on the V12 to get better / more accurate readings in a dyno for the whole power range, I got a spare exhaust section after the downpipes for that purpose, as then I could also have lambdas fitted and record data on the road.