Continuing the discussion from SU Fuel Pump for XK140:
By coil length, I am not referring to the ignition coil, but to the length of the diaphragm stem in the pump coil housing. There is a
2 3/8" and a 3" length. Can either pump be used on an XK140?
Thanks,
Alan
Welcome to the group, Alan.
I wasn’t aware that the LCS was ever made with the short body coil.
Long Body Coil on Large Capacity Housing
Short Body Coil on Small Housing
If you are asking which diaphragm to use in your long body LCS, it would be the long stem.
If you are asking if you can use a small housing short body pump, it may work ok around town, but you may run into fuel starvation at high speed.
BTW you can reply to your own postings, no need to open a new one on the same subject.
Rob
Rob,
Thank you for your response. I may be confused as to the measurements of the SU pumps. I thought that the diaphragm stem of 2 3/8" or 3" determined if the coil body was short or long. My LCS pump has a 2 3/8" diaphragm stem but just may be a long body. I have attached photos of the pump dimensions and hope you can clarify which pump body I have. I plan on doing a rebuild if it is correct for the XK140.
Thanks,
Alan
Hi,
The short coil LCS numbers are prefixed with a 1, so long coil AUA 52 becomes AUA 152. The LCS replacement pumps from Burlen are all short coil versions I think. They are interchangeable. Later LCS pumps used pressed end covers, but I have no idea if this coincided with the switch in coil length.
The SPC for MK 2 2.4 Jaguar shows progression from AUA 52, AUA 152, AUB 152, and lastly the switch over to AUF 301 (although they become AUF 303s).
All XKs were long coil. XK120 and early 140 used AUA 31, then XK140 uses AUA 57, and XK150 uses the stepped cap AUA 52.
I have both long and short versions if you need dimensions/pictures. Your picture looks like short coil to me.
Clive.
Alan,
Here is a comparison - note the two nubs in the base of the short coil, also in yours, and the general proportion of length/width.
Clive.
So, my question is, can I use the square body with the shorter coil on the XK140. Does the shorter coil have an effect on the amount of supplied fuel? W ill it supply adequate fuel at high rpm?
Thanks for your assistance,
Alan
The specs will presumably be on the Burlen site or manual? Empirically, I’d say the length of coil merely affects the force of contraction - i.e. the maximum lift height, and that would be related to stroke volume/chamber size.
The pulse frequency times stroke volume would tell you flow rate and if your car will run lean at high speed.
r
Alan,
http://www.liblbc.info/images/SkinnerUnion/akd_4792a.pdf specifically says long and short coiled pumps are interchangeable. MK 2 cars (all size engines) went from long coil to short coil during their production. I bet that the short coil has same number of turns on it - just that it is shorter and “fatter” in the housing.
I’m confident the pump you have will work.
Original pumps come up on e-bay fairly regularly, so with patience you will find the correct one for you to rebuild - and then you will have a spare ready to go!
No affiliation to seller, but all parts can be bought individually in US from https://www.sufuelpump.com/.
Regards,
Clive.
Is there a functional difference between pumps with alloy end plates and pressed steel? I have some of each if anyone needs a core.
I have read somewhere that it was cost cutting only. Remember that the thread length is shorter on the pressed ends fasteners.
Clive.
Clive & Peter & Rob
Thanks for all your advice. Being new to the XK marque I’m not yet familiar with all the resources. I have good direction now.
Thanks
Alan
The coil body lengths are 2-1/4" or 57mm for the short one and 2-7/8" or 73mm for the long one.
The SS/Jaguar history on these is that the 2-1/2 Litre saloons used only one of the small round body with short coil body pumps, but the 3-1/2 Litre saloons up to '48 used two of this same round pump in parallel piping. Apparently one was not enough to keep up with the larger engine.
Mark V used the new LCS Large Capacity Single with the square body and long coil body. Most of them were 3-1/2 Litres but they used the same one for the 2-1/2 Litre cars. The pumping capacity is given in the Mark V Service Manual and it works out to about a liter or a quart per minute.
XK120 also being 3-1/2 Litres used this square body LCS pump with the long coil.
So the question is, is the higher capacity due to the square body or the long coil or both? I’m thinking the long coil has a longer stroke, but I don’t know without measuring both. Could also be a faster stroke?
The stamped steel end covers replaced the cast aluminum covers in the late '50s I think, but it looks to me like just a cost cutting move, stamping in one shot in a punch press being a lot faster and cheaper than die casting and machining.
Following the link that Clive supplied, I came across this SU Fuel Pump link. Lots of info.
Alan
http://www.liblbc.info/index.php/78-lbc/skinner-union/fuel-pumps/72-su-fuel-pump-factory-literature
This is excellent, thanks Alan. Already it is correcting one or two assumptions I have held for years.
Rob,
Here is my guess. The pedestal and toggle are same parts on all pumps, as are instructions on setting the gaps. So I expect the stroke to be the same in all cases.
I also suppose all varieties of pump have same diameter diaphragm. In which case all pumps have the same swept volume.
Pump pressure will be determined by the armature spring.
So I think pump rate will be primarily determined by coil strength and inlet manifold efficiency. That is, by how fast the armature/diaphragm will retract when it is sucking fuel in. The LP pumps do have different coil numbers to the H an LCS pumps.
Clive.
On another note:
What is the size of the cheesehead screws for the side plates and the coil to body?
Alan
Alan,
They are all BA threads, 2BA I think. Take a look at document AUA 209 from the aforementioned Little British Car Library.
If you are in US you can get them from sufuelpump.com, there is also britishfastners.com. If you need taps, dies, spanners, etc., it can be cheaper to buy and ship from UK rather than buy in US, same with Whitworth tools (used on banjo bolts and SU carbs).
Clive.
In addition. You can get rid of the diode or capacitor and fit what is called a TCP, ( transient circuit protector), instead. This is NOT polarity conscious, and much smaller, so that a smaller endcap can be fitted if you wish. These TCPs cost about £1.00. Burlen sell them although electronic suppliers sell them cheaper…
There are some good rebuild articles on the MG website as the same pumps were used on the big Healey.
Response from Burlen regarding my inquiry if short coils where used on LCS pumps.
Alan
Thank you for you enquiry. The AUA 157 is built with the short coil housing and is the standard pump for the XK140C.
Kind Regards
Anthony Gillespie-Smith
Customer Services Advisor
Burlen Limited - The SU and AMAL Carburettor Companies
Spitfire House, Castle Road, Salisbury, Wiltshire. SP1 3SA
Tel: +44 (0)1722 412500 Fax: +44 (0)1722 334221 Email: customer.services@burlen.co.uk Website: http://www.burlen.co.uk
Burlen Limited is registered in England. Company Registration Number 2005550. V.A.T. Registration Number GB423 5232 84
