Hello all,
I just bought a very nice 74 4 speed maroon with black top and interior. This is my first foray into classic cars and also my first Jag. It is in not in likely to get invited to Pebble Beach or Amelia Island anytime soon but a blast to drive and looks great. It did win best of class in a local Jag club show in 2007. Motor, tranny, brakes, wheels, tires, and paint are all 95%. A couple of interior pieces could be nicer. The left side of the dash is pulling away and the console is cracked and there is a small tear on the drivers seat. The needles are stuck on the front 2 carbs and cant adjust. Fuel gauge does not work and the clutch master cylinder is leaking.

I only have a couple of things that need to get straightened out. It is pretty hard to start when cold. It will not start with just the choke on cold. I have been pumping the gas pedal a couple of time and can get it to turn over after about 3 tries at 5 seconds. After it turns over I need to keep the gas pedal in just a bit to keep it on idle. After a couple of minutes it is ready to go and runs like it is new. Is there a universally successful drill to starting one of these? It also runs a bit hot. The temp runs between the L in Normal on the gauge and the H. It almost got to H after about 25 miles at 75mph on the expressway then 10 minutes of traffic on the commute from my office to my house. They have a reputation for running hot but is that normal? Any fixes?

I will preface the next comment by saying in 1997 my daily driver was a 993 with track pipes. In 2006 my daily driver was a CTS-V with electronic cutouts. They were open a lot. The exhaust is also really quiet. I would prefer it to be a little more forward since it is a V12. I was hoping for a note more ferrari than XJ. Any reasonable mods?

I am looking forward to being part of the community and forum. Anyone around Louisville, KY?

 

You really need to have the carburetors sorted to get reliable cold starting. Even in very cold conditions, if the carburetors are clean, adjusted correctly, and the cylinders have good compression, cold starting in normally not an issue.

There are two Bypass valves on the carburetors - a temperature compensator and an overrun bypass valve. Both these valves can get carbonned up and sticky. The diaphragm of the overrun bypass can become very hard (it should be very flexible) and sometimes split. The temperature compensator (enclosed under the long, white plastic cover), has a small valve that is controlled by a bi-metal strip. This valve is very often stuck. There is a special procedure for setting the tension of the bi-metal strip; accordingly, don't remove this, but the rest can be dismantled and cleaned. Both these valves can have a bearing on cold starting, the degree of which will depend on how they may be stuck.

Regards,

Bill

 

Bill,
Thanks for the info. I have it going into my mechanic next week. Do you have an opinion on the operating temperature?
David

 

Temperature issue might be a lazy thermostat, and this is cheap to replace, so do this first. If it doesn't have an effect, the radiator might need re-coring. The rads are copper and easy to re-core, but finding a shop to do it might be difficult, but not in California I would have thought as there are so many classic cars there.

Edit
Sorry, see you are in Kentucky, so you could have problems. Are there many older Jaguars running around there ?

 

Thanks, I will look into that. There are a few other E Types at the mechanic I use but not a lot of classics overall.

 

Good advice from Fraser, but the radiator core will only need replacing if damaged. If its simply clogged, often the case, then even in the most extreme cases, they can be cleaned. In extreme cases where the tubes are blocked, the top and bottom tanks can be removed and "rod out" the tubes. This work is best left for a radiator repairer. Having the radiator inspected and thoroughly cleaned, if viable, is far less costly than having it re-cored.

If the cooling system checks out OK (all the points made by Fraser), ignition timing and an incorrect air/fuel mixture can cause overheating. You have already identified issues with the carburetors; accordingly, you should bring all of that into the investigation of your over heating problems. Get the carbs overhauled and tuned as well as having the ignition timing looked at before going too much further. This at least it eliminates this as the problem.

Regards,

Bill

 

When the gauge got near the H mark, were the electric fans running? I would expect it to stay near the center of the gauge while on the highway, when the forward motion of the car pushes air through the radiator but you need the fans at lower speeds to keep it cool.
As others said, get the carbs straightened out and it should start OK.

 

I did not notice if the fans were running or not but was pretty surprised that it was running hot at 65 mph on the highway. Carbs are certainly next on the list. What is a good budget number to have them rebuilt? Thanks in advance.

 

In my opinion you should opt for the full rebuild, as there are components that should be serviced as a matter of course, not included in the basic service kit.

In Australia, the rebuild kit for all four carburetors (CDRK1) retails for AUD480.00. The ultimate price will then depend if you do the work yourself (not difficult - just tedious). Obviously the carburetors have to be removed. They can be removed leaving the manifolds in place, but there will be a lot of swearing and dropping of the nuts when replacing the carbs. The easier method is to remove with the manifolds, and then further dismantle on the bench. You should replace the gaskets between manifolds and heads if you go this route.

After replacing, the carburetors will need to be synchronized and air/fuel ratio set, so as not to be too lean or rich.

A decent operator should be able to complete the job is a longish day. Attached are pictures of carburetors before and after rebuilding.



Regards,

Bill

 

One of the main problems causing overheating with the V12 is the fan thermostat switch near the bottom of the radiator. It is subject to road debris abuse and needs to be looked after on a regular basis.
However, the fans only operate when the airflow is inadequate, such as in a traffic jam, so your problem may be a simple cooling system flush, but be aware that overheating can wreck the engine, so be careful.

 

Welcome to the forum! Very nice looking car. Please give us a call/email with your details and we shall have a free parts book & upgrades book sent out to you.

 

As far as a carb rebuild, while I don't know what a professional rebuild runs, I'd recommend the rebuild kit off of XK's Unlimited. If you've got some time and some know how (or just the willingness to learn), they're pretty easy.

Good to see another Series III in Louisville. Too many guys with I's and II's around here. Check out Cars & Coffee on the first Saturday of each month at Captains Quarters if you already haven't.

 

Hello, I am just north of you a couple of hours in Indianapolis area!