New thread for Rodger on different versions of 9:1 compression pistons used in XKs.
The following pictures are of a piston removed from XK150S block VS 1331-9. I have all 6 if any numbers are not clear on this one. The casting says BRICO A22. There is also a cast code going across the split in the skirt, so part may be missing. It looks like M 5/3.
The main number stamped on the top is M1670 with an appened /1 that appears to be a larger font.
I have no history on the engine to claim originality of the pistons.
This looks like the same pistons installed in my November, 1957 built 9:1 CR 140. Mine also has a cast BRICO A22 but the slit took out the “I” in BRICO. The other numbers you list are different than mine. Above the word “Front,” on the top I can make out a 4 and what looks like the top of a 5 after it through all the damage. As one of the last 140s made, it would not be surprising if there were 150 parts used on mine.
Good decision Clive, best to start a dedicated thread…
Great photos of your BRICO 9:1 pistons ex VS1331-9 which makes it about Aug/Sep 1958…
Do any of your other five pistons have a sharper BRICO A22 branding???
As noted by Bob, looks to be the exact same pistons as in his Nov1956 XK140MC
I will have to add it to my files and have a good look, but in a couple weeks as we are off ‘touring’ first thing tomorrow, and I wont have access to my files while away from home… so more (from me) then, but that doesn’t stop any more input to this thread…
Roger
Have a good trip Roger. Here are photos of the numbers inside my surviving piston, and one of the top. I am guessing that “K56” may be the date of manufacture. If K stands for the 11th month, it would be November 1956, a year before my car was built. Clive probably has a similar number inside his pistons above the wrist pins.
C5724,
C7710,
C10649 flat top
C13794 dome top
C16339 dome top
SP bulletin A33 notes new 3.8 domed piston C16339 and refers to previous sets as flat topped. It does note if one piston need you can use old number C10649
attached are factory drawings from Hepworth for Jaguar 9-1 pistons noting 1959 to 1969 pistons although drawing done in 1969 but in theory same piston throughout the period also pics of one of these pistons showing Hepworth cast number 18394 inside and top
notes from Roger Payne
My particular interest is the various 9:1cr pistons as listed production available in the 1950s, noting from Oct 1952 to Dec 1959 there is listed four different Part Nos for 3.4 litre 9:1cr pistons, and with pistons needing to be a matching set, I am confident that each part number is unique to an exact piston interchangeable with the other five in the set, and as I am only talking about original equipment - thus all standard size - this doesn’t get into replacement/service spare parts oversize pistons…
There are FOUR part numbers I have found listed for production cars…
C.5724, C.7710, C.10649 and C.16339…
I would like to get definitive photos of these four part number pistons, thus the interest in Bob Currans Dec 1956 XK140 original equipment 9:1 pistons - are they C.7710, or are they C16339…
The C.7710 part number suggests same age/development as the C7700 and C7707 C-type heads - so 1952/3…
C16339 is more a 1959 era Part Number, so does that suggest Bobs 9:12cr pistons are C.7710s ???
Here are clearer photos taken from other pistons in the set. The casting number was as per Bob, M1513 AM.
It looks like Bob’s theory on date codes could be correct. Three of my pistons are A58 and the other three are M57. Assuming they did not use the letter I, M would be December.
The piston faces were stamped with the cylinder number.
Sorry for those contributing to this thread re 9:1cr pistons - but now back home catching up on back log…
My interest is to try and identify the evolution of the XK engine as relevant to the 1950s, including of course the available PISTONS, with the 9:1cr piston initially for racing purposes/special order only due to availability of suitable octane rating fuel…
The J.8 XK120 Spare Parts Catalogue, had a number of revisions/updates with the October 1952 issue being first to list availability of 9:1 pistons as part number C.5724. The next update of May 1953 retains this C.5724 listing, however in the next June 1954 update, the 9:1cr piston is now listed as a C.7710.
The C-type SPC (unnumbered/undated) shows the 9:1 piston as part number C.7710 but as an ‘Alternative’ to the C.6911 8:1 piston, and indeed other factory records show that all C-types were manufactured new with 8:1 pistons. It is believed that the C.7710 listing was for ‘Homologation Purposes’ allowing cars entered in certain events - where suitable - to fit available 9:1 pistons, which apparently did happen during the C-types competition period. The only evidence of factory fitted 9:1 pistons in these earliest days is the 32 XK120s recorded as being fitted with Engines with their engine numbers stamped -9S (this is not the time to debate the 32 count, its about the actual 3.4 litre 9:1 Pistons) These 32 cars date from first in July 1952, five from Sep/Oct 1952, two from April 1953, two from July but rest from end of Dec 1953 and 1954. (Count/dates may be a little inaccurate, based on a quick scan only)
So I am assuming only the earliest 1952/3 cars may have had C.5724 pistons, with the rest having the (revised/improved) C.7710 pistons.
Now I note that C.7710 part number is in the batch of newly introduced part numbers, including C.7700 as allocated for the ‘production C-type’ cylinder head, thus suggesting the C.5724 Pistons and the prototype C-type cylinder head, were just that - prototype/experimental, with the C7710 piston and the C7700 now more developed/refined/improved small batch production ready…
Getting back to the pistons. Its one thing to know their C.5274 and C.7710 Part Numbers, but what do they physically look like…
I have photos of the 9:1 pistons originally fitted to an early1954 one of the 32 factory equipped -9S XK120s - all six survive, being retained after engine was rebuilt back in 1960s (I think) - see attached pic, noting reason for rebuild …
Clearly a DOMED head piston - and I assume it must be a C7710 given its factory fitment to an early 1954 XK120. But there is nothing marked on piston indicating part number nor brand such as BRICO. There is a large cast P775 inside, and a sole large cast A also inside. So any comments, contrary or in agreement, are welcome, and still looking for a C.5274 and understanding the relative difference…
All the later piston detail/photos are great and appreciated, and I will fully digest in due coarse…
