Hello,
Aside from the change of letter prefix, is anyone able to tell me what the differences are between the T & Z series 3.5L motors in a Mark V please? And for that matter the differences between the S series 3.5L motor from a Mark IV and the T & Z motors from the Mark V?
Cheers,
Tim
The big difference is that Z series had steel rods. The MK IV engine S series lacked the adaptor under the water pump mounting that moved the water pump forward and the damper correspondingly was different
Different rocker cover ,MK V had vacuum advance and 3 screw for the suction chamber tops and alloy side plate . But little effective difference . many Mk IVs have Z series motors put in when the alloy.rods broke.
Itās a straight forward changeover
Ed got most of it, but the connecting rods story has a little more detail.
Alloy rods C.1049 with offset oil feed tube from T5001 to T6790.
Alloy rods C.2844 with center drilled oil feed passage from T6791 to T9999 and Z1501 to Z2198.
Steel rods C.2448 from Z2199 to the end.
There was an improvement in the tappets at Z1836 and in the pushrods at T9690.
There was a change to the rocker cover at Z2853 which I think was associated with a change in the air cleaner and the intake pipe.
This information is from the Mark V parts catalogue.
The change in the water pump, starting jaw and damper were in order to move the generator forward to clear the steering column on LHD cars, but to keep things simple they did it on all T and Z engines.
The rocker cover had a breather hole for connecting to the above mounted air cleaner. Some later Mark IVs including I think all the LHDs also got this.
LHD Mark IVs also had a remote mounted oil filter on the rear plate and an SL prefix serial number, because of the steering column.
My Z2170 3 1/2 Mark V engine had alloy rods when I rebuilt it.
S-series engines also had springs and collars on the pushrods.
The question still remains for me, what caused the S to T to Z change in nomenclature (and why not U, V, W, X, Y)?
Thank you all for your refections and for sharing your accumulated knowledge. So by all accounts you could have an S series motor with all the modifications and it would effectively be a Z series motor? I ask because I have recently seen an S series motor which appears to have all these modifications, in a Mark V! I have also seen and heard, as most of you have as well, that it was more typical for a Z series to be in a MK IV following catastrophic con-rod failure. Iām guessing that it might have been possible to have rebuilt an undamaged S series engine to Z series specifications and used it as a motor exchange? Arenāt cars and their stories fascinating!
I must get myself a Mark V Parts manual for more extensive reading.
Cheers,
Tim
LHD Mk IVās had an aircleaner on top of the rocker cover, lik a MK V , pretty much but they didnāt have the breather through the rocker cover. This was to allow the LH steering box, Incidentally the sump for MK IV had been changed from SS to allow for the LHD steering box arm to swing.
Some cars had extra springs on the pushrods, and idea that "Must have seemed a good idea at the time"but very few cars now have them , and donāt seem to suffer.
There had very early been quite different pushrods. I have some sets where the rocker had a socket instead of a screw and the push rods have balls and the cam followers have an adjustable screw [ like an SS1. Others with a ball at each end
The LHD Mk IVs wer e in reality a factory conversion, with some of th e lack of planning that implies The car we are doing at present shows signs of originally being a LHD chassis the factory has adapted , And some of the adaptions are pretty crude.
For Roger, letter W was being used for XK engines, letter X for experimental purposes. I have no guess as to why they did not use U, V and Y. Nor why did they start with T5001 and Z1501 rather than T1001 and Z1001? Letter V was later used for XK150 engines.
For Tim, the basic engine block and head are the same, so transferring external parts from one to another during an engine swap repair job would have been routine mechanicās work in the old days. And yes there was a factory/dealer exchange program for rebuilt engines, thus explaining one way an S engine could find its way into a Mark V. And if it was a RHD car they might not have bothered to change the water pump generator damper arrangement.
For Ed, I get that impression too, that the LHD Mark IV is a kludge job, a case of āWish weād thought of that beforehand.ā
Hi,
I have an SL- engine in my MKV DHC. (L for Left Hand Drive) I have swapped most MKIV parts for MKV parts, but still have for instance the MKIV generator bracket, now with 1" spacers to align the generator with the water pump and damper.
Apperently my engine had been rebuilt in the US and painted red. It was a big surprise when I had the head off that they had not planed/skimmed the block nor the head, BUT they had bored the block to 83mm +0.030" to use that size XK 3.4 Litre pistons and XK steel rods. Works well IMO. But still a surprise.
Cheers,
Pekka T. - 647194
Fin.
Hello again friends,
Hereās a thought, perhaps a wish? If as Rob says, there was a factory engine exchange program and presumably this occurred after production had finished on the Mark V, I wonder if the factory would have fitted the steel con-rods to the engine in such a rebuild? How could you identify if this was done without disassembling the motor? I guess that this might well be a question for most owners of Mark IV & V cars to determine if their cars had the troublesome alloy con-rods or the better steel variety? I must see if I can look at this late series Mark V again and see if the spacer behind the water pump and the corresponding crankshaft damper were transferred to the S series engine fitted to the car? As I recall it certainly had the correct late model air cleaner with the correct rocker cover and the later SU carburettors. These cars turn you into some kind of a super-sleuth or a quasi-historian as you look for original source material so as to bring to light the history of these cars (here I must confess to being an Historian).
Best wishes to all,
Tim
Just for info. the MkV crankshaft has a longer nose than the MkIV so you need a ānose jobā to use the MkV shaft in a MkIV and you canāt fit the MkV pulley/damper to a MkIV shaft.
Peter
Thank you Peter. I know a reputable Cosmetic Surgeon. I wonder if he would be prepared to perform a ānose jobā on a crankshaft? We really all need to get-together and write a tract on the foibles of Jaguar āpushrodā motors!
Best wishes,
Tim
I thought it was just abit longer in the plain, unthreaded section
We seem to have mix and matched successfully int he past, And the new cranks made are generic so suit either. i know of Factory changeover engines that were supplied un-numbered.{ subsequently ācorrectedā
Orā¦ just stick some extra washers under the nut.
Hi,
Iām not sure what washers I used, but I have a MKIV engine SL-prefix, MKIV crank and when I did the pulley exchange with Ed (MKIV <-> MKV) I did not experience any difficulties in mounting the damper and pulley. Is the MKIV chassis different in such a way that you would need to shorten a MKV crank to make it fit?
Cheers,
Pekka T. - 647194
Fin.
Iām not sure whether the MkIV is different relative to my SS but I donāt think there is enough clearance between the nose of the MkV crank and the front chassis cross member. I certainly couldnāt use the MkV pulley etc.
Peter
The factory engine exchange program was described in Service Bulletin #1 dated May 1st 1946, which was a long set of instructions for dealers about ordering spare parts, and how the factory had a Service Department for reconditioning engines, gearboxes, front and rear axles, differentials, steering columns, water pumps, oil pumps, etc. It stressed the importance of dealers getting the old engines back to the factory promptly. They were apparently short on āfloatā which I guess means they had none in stock with '36-37 1.5 and 2.5 engines, but promised the āfloatā of reconditioned engines would improve. Thatās how they printed it, with āfloatā in quotes. There is nothing describing what work went into the reconditioning.
I donāt think there is any way to know what rods you have unless you drop the sump.
Here are some shots of the Mark V installation with the water pump, damper and generator moved forward.
Looking at Robās pics. I have DXF programs to cut lock tabs fr the crank shaft damper ā¦ and most other locktabs [ flywheel, SS lock tab as well as MK IV/V].
If anyone needs one, Iām happy to email the file[s] to either them of their laser cutter/ water jet cutter.
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For those that do not know!
The longer crank nose provides a ālandā for the split collet used with the MK V
damper, When using this damper on a short nose crank the collet might
engage, but only by 1/16"- 1/32". Machining a flat inside the damper adapter
to take a flat washer perhaps is preferable.
By machining and mounting a ābespokeā pulley on a MK V damper adapter
is one solution if there is a problem with the early, non damper, alu pulley.
There is not a problem using the longer crank in a SS chassis.
I have included a XK collet for ref.
Hi Peter,
The problem in trying to use the longer crank in the SS chassis is that itās too close to the front cross member.
Peter