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Otter Switch Bolts

Otter Switch Bolts

The following is not recommended for the non-authenticity owner or even the faint-of- heart judge. The Problem: The JCNA Concours Protest Committee, of which I am a member, has been asked to rule on a protest resulting from a deduction made for a car having what, in a judge's opinion, were wrong-headed bolts holding the starting-carb thermostat/otter switch. The judge said that the three CORRECT 5/16" bolts had a small depression or indentation in the center of their heads and that any other bolts were wrong. To me, this is a real "nit-pick" since I know of no reference material by which one could possibly verify whether Jaguar used the same supplier for those particular bolts on all their 120s. Based on what I know about 120s, I would not have deducted for the bolts, even if I had noticed them. I do know that those bolts are highly subject to breaking-off during removal. However, I did find a couple of spares of the type the judge was referring to. They are 3/16", 24 thread. The heads have a depression in the center which contain a capital letter "R" and the periphery of the head has the word "LINREAD". The Question: If any of you have cars (120s) whose engines you believe have been kept original, what do the bolts on your starting-carb thermostat/otter switch look like? Are they smooth-topped or do they have some sort of design or lettering on them? My sincere apologies to those who are still gagging on gaiters and bonnet props but "because it's there", I owe it to the protester and the judge to ask the "list" rather than rely on my own resources. Direct replies are welcomed as appropriate. - Thanks, Dick Cavicke

I have a late 120 OTS, chassis number S676018, and three bolts in question are 3/16-24, 1/2 inch long. They have a depression in the center of the hex head with a raised letter "S". No other markings. There is also a slight bevel on each of the six points of the hex head. - Edward Peterson

Dick C: You really take the cake! I thought we were getting pretty bad here in Sydney with the argument about the reverse side of the hood material (btw, I concluded from info received and my own sample that the correct reverse side looks like denim reverse - straight lines), but the bolts that hold the otter switch ???! Come on, Dick, admit it, you made all this up. But just to prove my own gullibility, I will set out a few observations. Parts books: XK120 10: early cars to W1250 - C 168 "thermostat on outlet elbow" (Plate B 98), secured with 2 set screws CS 419/3H and shakeproof washers C 723 (no gasket was listed). The illustration showed quite a large part. Later cars from W1251 on had part no. C 2474 with a gasket C 2475, and three set screws C 7134/1 and shakeproof washers C 723/A. XK140 19: Cylinder head section - C 2474 - "thermostat at top of inlet manifold for carburetter automatic choke" - F74. Illustration showed a small part. Same setscrews and washers as the XK120. XK140 280: cable from carb solenoid to thermo switch was C 2884 (Lucas 859389) - but still did not find the nut for the top of the post! XK150 1/27: same desc as 140: C 2474 also. Plate 5-77. Does not look the same as the 140 illustration. Secured by 3 set screws C 7134/1 and shakeproof washers C 723/A, with a gasket C 2475. So aside from a few very early cars, the screws were the same, C 7134/1 for all XKs. A few observations from my photo collection (not confined to 120s, see above): (1) F1026-8 (late 120): the three heads seem to have a largish R in the middle. Not that easy to see, but prob flat rather than indented. (2) 661123 (latish 120) - the one bolt I can see, appears to have a round indent in the head (3) XK150 S VS 1981-8S: indent in middle, with (smaller) R in middle and LINREAD around the raised outer circle. (4) Other XK150s 825231, 836021, 824479, 824750, 837506, 824445 (and others, I gave up listing them) - same as (3). The 140s I have were clearly not original. So we have the same part number apparently changing through XK production, not unusual I would think. The 120s are different from the 150s which appear consistent. The judge might well be right, but let's see what other observations there are on this list first for the 120s. - Regards, John Elmgreen

Hi Dick Cavicke & all -- I checked the starting carb. thermostat/otter switch on my original Mk IX, 792817 BW, built 12/15/59, and it's held on by three 5/16 bolts, with center depression and "R" in depression, and "LINREAD" around outer bolt head -- Dick, you said "3/16" -- was that a typo? Mine come out with a 5/16" socket. In any case, my original Mk IX Spare Parts Catalogue calls these nuts out as c.7134/1 -- I recall seeing the same part # in some other people's input, so I suspect Jaguar stayed with at least the bolt (if not the switch itself) through the 3.8-litre engines. Hope this is helpful; finally -- happy holidays to all of you! Larry Martz

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