Dip stick correct one?

Hi, After my escapades of importing my car from the UK to the US and all the trails and tribulations involved with that,including damage to the car, parts left in the UK, then retrieving most of them this week and finding some of them damaged!
I am now in the position of building her back up, one part that I have have from the car being sold to me is a chromed dip stick, which I assumed to be correct, however I removed the one in situ to find it is a different size, Please see pictures, I guess people don’t often get asked the question how long is your dipstick ! but could somebody tell me which size is the correct one from these photos

I think there is a rule on this forum that no question is too trivial.
In fact the subject of dipstick identities has come up on the XK forum more than once.

Here are mine.

The one with the bigger head is from the 2-1/2 Liter 1938 SS.
The lower end is machine cut into a half-round.

The one with the smaller head is from the 3-1/2 Liter Mark V.
The lower end is a flat strip riveted to the round shaft.

SS overall length 22"
head diameter 1-1/4"
collar to tip 10-1/8"
marks at 9-7/8"; 8-5/8"; 7-5/16"

Mark V overall length 19-3/8"
head diameter 3/4"
collar to tip 10-1/8"
marks at 9-7/8"; 8-5/8"; 7-5/16"

That’s good information, Rob, I’ll check mine. The correct high-low level range is important.

To illustrate, a colleague with a 1 1/2 Mk IV had a noisy gearbox. The cause was eventually revealed to be the wrong dipstick - it was from a six cylinder’s gearbox which is bigger, which meant the oil level markings were about 2cm lower.

Similar to Rob’s photos, my 3 1/2 Mark V engine shows full oil at 7 5/16" inches from the stopping collar on C.2683 Dipstick complete Plate H.41.

This topic also has come up on the XK forum, because with the Laycock-DeNormanville overdrive there is an extension on the top cover, for which the dipstick is longer.

The full oil level is 4.625" below the top of the cast iron case, so the countershaft gears are mostly submerged, and the mainshaft gears are just dipping into the oil.

Off topic, but a question I’ve been meaning to ask you pre-XK owners … I’ve often read comparisons, or at least opinions, about the handing and driving differences between the XK120 and the E-type, the latter judged to be far superior (I prefer “different”). How might you characterise the difference between the pre-War cars and the XK120?

Take a look at: SS v. XK Engines

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Ha, ha! I don’t recall ever using the term handling when describing the driving experience of my '38 SS saloon. The Mark V on the other hand has the same torsion bar IFS as the XK120, and I would say it is pretty good, can keep up with modern traffic anyway. There isn’t a cement mixer on the road that can outrun me.


The obvious difference is the more efficient and superior engine with a significantly higher output. The biggest difference is in the chassis specification - beam axle on cart springs vs independent on torsion bars, mechanical vs hydraulic brakes , worm and nut vs recirculating ball steering, narrow vs wide section tyres.

First things first: For the life of me, it seems the length of my dipstick has always been an issue. Now here we are once again with my 1947 3 1/2 litre.

Collar to top notch: 8 1/8 inches
Collar to bottom notch; 8: 5/8 inches.
Collar to tip: 10 1/8 inches.

I don’t remember how much oil I put in it. Only that I filled it to the top notch. So am I wrong? It doesn’t look like the collar can be easily moved.

Now for the handling: If you haven’t raced your SS or Mark IV in a JCNA slalom, you should give it a try at least once. (Although there is a pre-race inspection, they don’t ask to see your dipstick.) The suspension lets out some very noticeable snaps and pops. I thought perhaps I’d broken a spring leaf, but, didn’t. Here’s John Boswell’s '38 SS DHC and my '47 Mark IV saloon (both 3.5 litre,) going head-to-head at the International Jaguar Festival on 1 October. We were both able to chirp the tires from the starting block, and then lock up the wheels when we slid into the stop box.

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George, I am inclined to think that your dipstick is from an XK engine, not a pushrod.
The top or full mark is too low.
XK engine dipsticks
If it were mine, I would make another notch at 7-5/16" below the collar.

The full oil level on the pushrod engines should be about 1-1/2 inches below the sump to block gasket joint level.

Hey Rob,

That’s got to be at least another quart of oil, right? Wish I had taken the dipstick measurement from the bottom when I had the pan off (three times, unsuccessfully trying to stop oil leaks). My overall dipstick length from tip to knob is 13 inches so you’re probably right about it being XK. It had an XK distributor in it as well, when I bought it. .


Yes, at least a quart, maybe two.
The XK distributor has a different driving dog on the bottom end.
It was probably a 40149 Mark V distributor, which was the same basic vacuum advance DVXH/6A model as the 40199 in the XK120 but with a different driving dog.

It was a DVXH6A 40198B, dated 4 50, so must have had the drive dog changed. Someone’s going to get a surprise, as I donated it to the Coventry Foundation as an XK distro. I replaced it with the correct 40093B. I was surprised that the 2 distributors clocked 180 degrees from each other. I had to rewire the cap after I finally figured out why it wouldn’t properly seat in the same configuration as the one I had removed.

My apologies to Mike about hijacking your thread.

40198 is for an XK120 with 7:1 compression ratio, kind of unusual, at least in the USA as they were usually 8:1 here.
The upper shaft with the 6-lobe cam can be assembled on the lower shaft two ways, 180 degrees apart relative to the driving dog.

Ah, but my Mk IV spent the first half of it’s life in New Zealand. It was imported to the USA (Chicago) in April 1986. That owner passed away several years ago and his brother finally released the car to BHCC. I bought it from them 2 years ago. I suspect the non-standard distributor had been in the car predating that time.

That might explain it. The 7:1 CR cars went to countries where the gasoline was not so great, and I think New Zealand might have been one.

Hi Looks like the shiny newly chromed dipstick I have is not the correct one and the scruffy old one in the car seems to be the correct one, I have a few spares that I am going to advertise on here when I get them sorted out so I will list it with them
obviously have the correct length of dip stick is important for correct oil levels

Whilst we are talking about distributers can I ask the questions to you knowledgeable people, why does the distributor have two locking devices on it, IE the one on the ring plate that bolts to the top of the drive tunnel and then gets tightened around the distributer body and then another grub type bolt that screws into the distributer body to stop it revolving below that ? is the one that screws into the drive tunnel from the side into the recess just to stop the distributor from screwing itself out, and gets tightened just enough to stop this, but to allows the distributer body to revolve to set the timing? and then the body clamp is used to hold it in place ? I am fed up of spelling distributor now so will refer to it as a dizzy !

Are you describing the distributor with manual advance controlled by a lever on the steering wheel?

Hi Rob
No the one with mechanical advance on the dizzy, please see picture I took off one of Peter scots posts,you will see there is the securing nut to hold the plate on the dizzy then below that one ( Not arrowed) there is another bolt that goes through the drive tube and secures the dizzy in position that way also

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