What Fuel to use?

[patteian]

Just purchased my E-Type. Previous owner had not used it for many many years and cannot remember how it was tuned for fuel.

It is a twin Stromberg USA import converted to RHD. I have been told there are no modifications to the engine, so 1:8 compression, with the original standard head.

I am assuming I need to use an additive to unleaded petrol to avoid any issues?

Castrol Valvemaster / Valvemaster Plus seems a popular make, does anyone have any bad experience with this additive?

Many thanks in advance for your advice.

:)

[e-bygum]

Be aware that these cars suffer badly from lack of use, particularly if little or no maintainance was done while they were laid up. The conditions under which they were stored can also have a major influence.
For example was the brake & clutch fluid changed periodically? If not you may find that there is corrosion inside the system components which will ruin the rubber seals and cause things to seize up.
In terms of fuel, make sure the tank and the whole fuel system is free from rust and varnish before you fill the tank with new petrol.
I believe that the XK engine can be run ok on unleaded fuel without the need of any additive, the V12 certainly can. No doubt others will confirm/dispute this, as well as giving more advice on what you should do to an 'E' which has had a long rest.
Welcome to the list and good luck getting it through the MOT. Mine had stood undercover for 5 years when I bought it 4 years ago, the body is good but I am still working on the mechanicals to get it through the test!

[Moeregaard]

Unleaded fuel shouldn't pose a problem with your car. What can cause troubles is the alcohol that has been present in U.S. unleaded fuel in the past few years. There have been some compatibility problems with the rubbery bits in your fuel system, so I would plan on a carb and fuel pump rebuild before using the car regularly.

The points made regarding the rest of the liquids are well made. Occasionally, some "mechanic" will service the entire system with DOT 3 fluids instead of the required DOT 4 GTLMA stuff. Personally, I would avoid the silicone (DOT 5) fluids; I don't think they're worth the trouble. If the car has been sitting, I would plan on rebuilding the brake and clutch systems. Few things will lead to grey hairs like bringing an E-Type home with no hydraulics.

[Car-Nut]

I hold my hands up Im no mechanic but what do you have to do to convert these to unleaded. I know I read something recently where something gets done to the head......

[kingzetts]

Lead in fuel had two effects - raising the octane rating of the fuel, and the side-effect of lead deposits on the valve seats preventing valve seat recession. Basically if the valve seat is not made of a hard-enough material, the repeated hammering of the valve into the seat causes the seat to be worn away and the valve gradually buries itself deeper into the head. Eventually the valve clearance is lost and the valve doesn't seat properly.

Many "classic" engines had perfectly good valve seat material when new to withstand recession without lead and not all of them need hardened valve seats for unleaded. IIRC it was mostly UK-only engines which tended to suffer - most engine types destined for export markets tended to have harder seats as petrol in "the colonies" was of variable quality. I don't personally know about the XK - others will be able to tell us - although I think the valve seats are OK for unleaded as standard.

Some classic engines ran quite high compression ratios (above 10:1 - early Rover V8s spring to mind) and were designed to use the highest octane rating fuel (the old 5-star). With even super-unleaded having a lower octane rating than 5-star, some such engines need either to have the compression ratio reduced (new pistons, or simply a thicker head gasket) or in less extreme cases retarding the ignition a bit may be enough - or need to use an octane booster.

As far as ignition timing goes, an engine with only an 8:1 CR like an export-spec XK is unlikely to need timing adjustment to take modern unleaded - the CR is simply not high enough. Tuned XKs with higher CRs may be a different story.

[Heuer]

All XK engines have hardened valve seats as standard (necessary because the heads are aluminium) so will run perfectly well on unleaded fuel without modification or additives. The US spec engines had a 8:1 compression ratio because of the low quality fuels generally available over there so will easily run here on standard 95 octane unleaded. The UK/Europe XK engines had a compression ratio of 9:1 so to avoid pinking it is worth filling with the equivalent of the old 4 star - super-unleaded. This ranges in octane value depending on manufacturer: Texaco Super, BP Ultimate etc are 97 octane, Shell V-Power is 99 octane. My car has a 9.5:1 compression ratio and runs perfectly on 97 octane and I have run it on 95 octane when none of the luxury stuff was available.

Some cars produced in the 60's had compression ratios of 10:1 or above and required 5 star fuel (100 octane) in an attempt to get more power from a poor design but Jaguar was not among them.

[patteian]

Many thanks for all the advice, 95 unleaded it is!

I am about to purchase a used Mityvac to pump out the brake fluid and replace with dot4 although I may need to flush though given the slave reservoir has a cork for a float! However it does look like all the piping was replaced at some stage which will hopefully make the job easier.

Fortunately there was a new clutch master installed just before the car went off the road, this appears to work well at the moment!

[andyp]

...given the slave reservoir has a cork for a float!

I hate to tell you this but the cork is a standard Jaguar part.

Andy

[kingzetts]

But the cork float should be enclosed inside a metal cylinder.......

[Moeregaard]

The light alloy cylinders in my car had been completely digested and were lying in little piles on the bottom of the reservoirs when I took delivery. It appears that this is not an uncommon occurrence.

Regarding fuel, in the States we were forced into unleaded in the early '80s. Our octane values are averaged from the Research Octane Number (RON) and the Motor Octane Number (MON). The best stuff available to us in southern California is labeled 91 octane. This fuel is marginal with a 9:1 CR, but does work pretty well if the timing is set properly and full-throttle applications are avoided at very low RPMs. This also assumes that the distributor's centrifugal-advance mechanism is working properly as well. The lack of lead has not been a problem.

If I were going to be operating where the fuel is of an unknown quality, I would probably fit 8:1 pistons. For you guys in the UK and Europe, where 95 octane is available, 9:1 CR should not present any troubles. Des Hamill makes an interesting point regarding CR in his excellent book on tuning the Jaguar six, stating that high CR is not essential to getting a lot of power from this lump.

[Heuer]

I am about to purchase a used Mityvac to pump out the brake fluid and replace with dot4 although I may need to flush though given the slave reservoir has a cork for a float! However it does look like all the piping was replaced at some stage which will hopefully make the job easier.

The Mityvac is a great tool. The only problem I found is the rear brakes on the E-Type can be a bugger to bleed properly even with the Mityvac - you may need to put some pressure on the brake pedal to get the fluid moving. If the fluid you remove is in any way discoloured or smelly it means the seals will need replacing throughout the system. I had black fluid coming out of my clutch system no matter how much fresh fluid I put through it. Replacement slave cylinder (well three actually - the new ones are crap, eventually found a NOS Lockheed slave on on eBay) solved the problem.

[attwood]

My Series 2 OTS is US spec, produced in November 1969 and first registered in 1970. It still has the original engine with a 9:1 compression ratio, confirmed by the Heritage certificate.

The chassis number is 1R11510 and the engine 7R 9006-9 (the 9 suffix indicating the compression ratio).

I've not driven the car yet so I can't comment on the fuel!

Regards, Dave.