SNG, XK’s, Terry’s, and Welch and all the others supply this part. Be sure to buy the corresponding o’ring. I got mine from XK’s.
I’m only guessing as to why the metal casing is used, perhaps it is to keep the seal round in the fitting process and preclude elongating it by stuffing it into a groove that is too small. If it doesn’t slide in then machining is required.
Maybe so. I use a 3.8 E-type smooth sump and the block & timing cover are from a ‘64 3.4L Mk2. I have three XK120 sumps (WHY?) and maybe have one of the seals. I’ have to do a bit of checking.
You are probably correct on that. I found one each of the two types of spacers, but could not find the XJ6 seal. For comparison, I measured the seal cavity in a XK120 sump and a 4.2L E-Type sump (newest thing I have on the shelf). The groove in the XK120 sump was about 2-1/2" ID by 1/2" wide and the E-Type was about 2-3/4" ID by 5/8" wide (round numbers).
O-ring seal face/spacer on the right, is slightly longer to compensate for the fact that you leave out the slinger disc when it is used.
The one thing that I was taught about rope seals is this (back to my mid-70’s Model A days)… Rope seals have to leak to exist, for if they are bound so tight that the don’t leak they then have to wear until they do.
The grooves in the 120 sump and timing cover are contoured to accept a rope not the later XK140 and subsequent models rigid lip seal.
Jaguar changed to the rigid lip seal starting with the XK140 to eliminate the leaky rope seal. The seats for this new improved seal are sharp cornered in the sump and the timing cover and are larger than the 120 rope seal to accommodate the new standard lip seal. Unfortunately the 140 seal doesn’t fit XK120 parts without machining both the sump and the timing cover groove to enlarge them to match the larger lip type seal body. This was commonly done though as a retrofit improvement to XK120s.
My rope seal leaked for years until I replaced it with the special retrofit lip seal in 2014.
I found that the special replacement lip seal fitted into my original 120 sump okay but did not fit the timing cover. I had a spare cover in my stash and it fitted in that one fine so I swapped them with no problem. Of course, I checked that the cover did not stick up above the gasket surface of the block and was fortunate that it did not.
Unfortunately I did not know about the o-ring sealed spacer that Tom mentions above and that job is on my radar the next time I am addressing that area. I get some leakage through the original spacer because it is unsealed. Wish I had known them.
Good explanation, JBrady5282 - I get it! I will order the spacer with o-ring from XKs Unlimited. Where should iI go for the rigid metal-cased lip seal? Does anyone have a part number? I’m going to stay away from the Teflon squidgy type, as I think seal distortion is probably the cause of my leak.
To find TDC accurately, I use a timing wheel. This is a big degree wheel which is bolted to the nose of the crank using the pulley nut. Fix a rigid pointer, a stiff bit of wire or whatever, with the tip really close to the marks on the timing wheel. Set up a DTI on the piston you want to know TDC of, and turn the crank until the DTI starts to move. At a few degrees before full deflection of the needle, turn the timing wheel so the pointer is indicating 0. Set the DTI to 0 at this point also. Now turn the crank - the DTI will go to the peak position (doesn’t matter what that is), and as you continue turning it will come back to 0 again. Now see what the timing wheel is reading - it’ll be so many degrees after the 0 you set it to - halve that number of degrees and turn the crank back to that number. The crank is now set at exactly TDC, allowing for dwell.
I do this every time I take the head off. Some timing damper insulators can deteriorate, allowing the timing marks on the rim to move relative to the centre casting. This check confirms the marks are still accurate.
that is nice Tadek…I do think a single white mark at the timing you want is helpful for timing lite use…With the flywheel teeth visible thru the inspection hole…and knowing 2.73 D per tooth…it is easy enuf…to mark the flywheel tooth you want…and the damper edge…perhaps a second mark also…one for static, one for rpm advance. I like to at least once…before work…verify TDC #6 compression…via a dial indicator in spark plug hole…and then make a scribe on the damper edge…it can be seen when not running…but won’t show up on a timing lite: could be a darker paint dab on the TDC flywheel tooth…a white mark on your timing advance set tooth. Nick
I’ve just received my O-ring type spacer from Guy Broad (about £40). I notice from Mike’s pictures above that the original spacer has a slot to locate on the crank with a keyway. Obviously, the replacement doesn’t have that feature, as it would get in the way of the O-ring. My question is: why wouldn’t the new spacer have a tendency to turn on the crank with no keyway to lock it in place? I can only assume that the cone for the damper is tightened on so tight against the spacer that it prevents it from turning. I realise there would be very little friction from the lip seal to cause to want to turn. Would it be a good idea to use silicone sealant as well as the O-ring (taking the usual care not to overdo it)?
Chris
