Regarding Rob’s SU Bulletin: The double contact arrangement is much more reliable than the single contact one. I swapped out my single contact set for the double and it’s not difficult to do.
Peter
1 Like
Peter,
There’s a Nov 2021 ad in this Forum for an extremely rough Mark V for sale in Australia. No drivetrain, interior, glass, etc. I sent a message asking if he’d be willing to sell parts, as I saw in one of the pictures it still has a very rough toolbox and cover. I got an email reply from a Mr. Barnes Fairman this a.m. that he’s sending someone out to look at it and take some pictures to send to me. I don’t see the fuel pumps in the pictures, but they could be buried in the pile of junk in the interior or in the trunk…excuse me, boot.
Also, there’s an ad in this months hard copy Hemmings Motor News titled: “Jaguars: splitting up for parts.” It lists Mark IV, and pretty much every model since then. The ad says the location is NY, and gives this phone number and email address. 315-649-2861, petroske@tds.net. 315 area code is in upstate NY. I called and left a phone message last Thursday. So far no response. I’m getting ready to send an email. You or anyone else, if you’re able to make contact please let me know. Regards, George
Hi George,
I think the MkV has the pump under the floor so not the correct sort for your MkIV.
That said, I suspect that there is nothing wrong with the pressure from your pumps because when you were checking the fuel level at the top of the jet tubes you were not getting fuel flowing out.
I am not sure that you will be able to recover your difficult needle if it has been bent and/or marked but it’s always worth trying it. I assume that you don’t have some non-standard air silencer fitted or totally clogged up. Mind you, there’s nothing wrong with you running without the silencer for checking the sootyness of the plugs.
BTW, I’m located in Edinburgh UK. Where are you?
Peter
Peter, I was sending the info about the Mark V fuel pumps for you, as you said earlier you were looking for a set of fuel lines.
I don’t think the needle can be saved either, but until I find another, it’s all I’ve got. Burlen lists DY and GA needles. I’m putting an order together with them right now. The only question is whether I’ll order 2 more carb rebuild kits (at over $100), as the kits I got from Moss (close to $300) don’t include the rubber gaskets sealing the plugs beneath the jets.
I’m in Cocoa Beach, FL. I haven’t been to Edinburgh since 1980.
Regards,
George
It has an aftermarket air cleaner/silencer. Relatively clean element. Haven’t found a replacement yet, but looking. Also looking for an original air cleaner for it.
Hi George,
There are several Peters on this forum. Please excuse me for assuming you were addressing me (I only have an SS Jaguar 2.5 litre saloon.)
There is a good chance that that paper filter will give significantly greater airflow obstruction than the crumpled wire restriction on the factory silencer and may be the reason for your rich mixture.
Peter S.
2 Likes
Yes, Peter, as you had responded to this thread previously, I was responding to you. I had the paper filter off several weeks ago and ran the engine. No change in it running rich, but good thought.
Single vs double points, Peter Scott is quite right as usual, my L type did indeed have single, where HP had double, obviously longer lasting and better. I rebuilt mine with double, don’t think anyone sells the single anymore anyway.
You also have the option of rebuilding them with the modern transistor or Hall effect electronics conversions that some of the vendors sell.
Almost all Mark Vs except the first 121 saloons had the square body LCS type mounted on the chassis under the body, not really for Mark IV, although of course just about anything can be rigged up.
Are you looking for the tool tray and lid? The tool tray for Mark V is not the same as for Mark IV, different tools and layout. The lid might be the same as for late Mark IV but I think not all, maybe different hinges?
I didn’t know Fred Petroske was still around. I think I bought something from him about 40 years ago.
You have the above-carb air cleaner plenum, originally designed for LHD Mark IV to clear the steering column, but also revised at the lower rear corner and used on all Mark V which had an even higher steering column.
RHD Mark IV would have had the below-carb air cleaners like mine.
1 Like
Hey Rob. Yeah, I know the tool kits are different, but the cover looks close to the same. Even if its not precisely correct, anything’s better than nothing. I’m afraid I’m going to drop something on the inside of the trunk lid, and then I’ll have a ding which will look like crap from the outside. Regards, George
And yes, that’s the air cleaner I’m looking for. I have no idea how my car wound up with the one it has.
Can confirm burlen U.K. were unaware of the lack of spring on the carb piston for a 46 3.5 l saloon but they certainly have the correct carburettor rebuild kits with correct needle. My carbs had a choke mechanism that was changed to the ventral screw and they could supply all these fittings as well.
I also needed to replace the carb dampers as the originals didn’t stop the piston rising too quickly. They were able to make these on a special.
All the manuals supplied suggest the S U carburettor is supposed to run on the rich side with the final mixture setting set on the lifting the piston test to see if engine revs or dies?
1 Like
The fibre washers that are located inside the bottom carburetter cap nut were S.U. part number 3159/1
The float chamber top serrated fibre washers are still S,U part 1928 and if you were keeping up with the up to date S.U thinking of the 60’s you would be fitting two on each carburetter.
Both these special fibre washers are available from Burlen Fuel Systems, usually in packets of ten and it is sensible to have some on hand particularly if you have H type Thermo carburetters which seems the case here,
I suppose one could say the SU carb was in constant development.
1938 SS 2-1/2L H3, brass piston, no spring, no damper on the cap.
1950 Mark V 3-1/2L H4, brass piston, no spring, damper on cap.
1951 XK120 3-1/2L H6, aluminum piston, spring, damper on cap, vent hole gusset on dome.
All is back together and running the same, although I didn’t expect any improvement with the boogered up needle. I ordered a pair of DY and GA needles as well as 2 rebuild kits from Burlen. Hopefully they won’t take too long to ship.
I confirmed I do have single point, Type L fuel pumps. I reinstalled them in their original locations, on top of the firewall.
1 Like
George - and others,
A bit belated, so sorry, but been away from home at the Melbourne F1 GrandPrix - somewhat removed from SU Carburetter leaks 
But see attached - this is a copy of the SU CARBURETTERS Co - note correct spelling of Carburetter - actual 3-1/2 litre Mark IV Spare Parts Listing for their twin H.4 ‘Thermo’ set-up to their complete AUC.449 Specification, as applicable to all Mark IV with Engine Nos S.26 to S.3959.
This is as good as it gets, re picture, description, and SU Part Number for every item included in the complete set-up, and usefully also advises original surface finish for those wanting concours accuracy…
NEL.191.52 JAGUAR 3.5 LITRE.pdf (3.2 MB)
SU also published SERVICE INSTRUCTIONS for their H4 carburetters, being one of the companies supplying Jaguar that you find produced better Parts and Service information than Jaguar did themselves for the bought in components/assemblies…
1 Like
Hi Roger,
Thanks for the link to the SU parts list and also for pointing out the spelling error. I confess to perpetuating that error in my website although I’ve now updated my page on the SU Starting Carburetter. I was quite surprised at the er ending and I see that Bentley also thought that it should have an or ending.
Restoration information for Vintage Bentley cars (vintagebentleys.org) as does Collins Dictionary:
Carburettor definition and meaning | Collins English Dictionary (collinsdictionary.com)
Also The Automobile Engineer:
The Automobile Engineer Oct 1937.pdf (nostalgiatech.co.uk)
That said I see that Jaguar and SS are quite consistent in using the er ending.
Peter
1 Like
Hey Roger, thanks a million. I see from this SU Parts Listing mine is missing the warm up carb spring, which goes between the solenoid and the plunger. Hmmm. Wonder if without the spring, the warm up carb is letting additional fuel into the rear carb. Thoughts? Thanks again, George
Any of you wishing to correspond directly with me, my email is: gtcole@peoplepc.com. Or you can text me at 321-848-1770. It does allow our communication to be private, but prevents the pooling of thoughts. Thanks, George
Looking at the diagram in Roger’s link a little closer, the entire warm up solenoid is different than mine. Mine uses 2 wire clips to attach it to the carb, where as the one in the diagram uses a stirrup and screw. The diagram has "(Mark II solenoid) beneath it in parenthesis. There is a note about it on the part number page stating the Mark I solenoid was replaced by the Mark II solenoid, with a the stirrup and screw, but doesn’t mention whether there were any other differences. So from that I think I’m missing a spring.
The solenoid pulls up the circular plate H and the spring pushes the plate H against the pipe end when the choke is switched off. If there was no spring then it is possible that fuel could be sucked in although I would have thought that the intake suction would have held the plate closed. The various solenoid mounting schemes are not critical as long as the solenoid is held in place.
The SU Starting Carburetter (nostalgiatech.co.uk)
Peter
1 Like