Sevens FAQ


1. Introduction

The Sevens mailing list is for the discussion of anything related to Lotus and Caterham Sevens, including similar cars such as Westfields, Robin Hoods, and Sylva Strykers.

This document is the list of Frequently Asked Questions for the list; please read it before posting to the list. It is also intended to grow into a general repository of useful information about Sevens. If you have any comments about this FAQ, including corrections or additions, please send them to the maintainer, Jason Brown <>. In particular, I have only been able to test the HTML version of this document with Microsoft Internet Explorer 3.0 and Netscape Navigator 3.01; please let me know if you have any problems viewing this document with these or any other browsers.

1.1. Revision history



First started...



Moved to Psion Series 3a.



Beta version released.



Moved to Word 97.



Released to list members.

1.2. Copyright

This document is Copyright (c) Jason Brown 1997. Permission is hereby given for this document to be copied in either electronic or printed form, provided that the complete document, including this copyright notice, is reproduced, and that no charge is made.

1.3. Disclaimer

Before you act on any of the advice given in this FAQ, please bear in mind what you paid for it. Whilst the editor believes the contents of this FAQ to be true and correct, no guarantee is made.

1.4. Acknowledgements

The biggest "thank you" goes to Steve <> for setting up and running the list and associated web site.

Thanks also to all the people who directly contributed to this document: Brent DeWitt <>; Felix Klauser <>; Kiyoshi Hamai <>; Brian Poulton <>; Clive <>; Bryan Biggs <>. Thanks also to everyone who posts to the Sevens list - it's a great read for any Seven nut.

Those who volunteered to beta-test / proof read the FAQ before publication: Steve <>; Ben J H-Tomkins <>; Felix Klauser <>; Bryan Biggs <>; Paul Ranson <>; Brian Poulton <>.

1.5. What is a Seven?

A Seven is a small, lightweight two-seater open-top sports car, which is supremely nimble and quick.

The Lotus Seven was launched in 1957, powered by a 40bhp Ford 1172cc engine. The Lotus Seven Series 2 followed in 1960, and the Series 3 in 1968. In 1970, Lotus radically changed the shape of the car to create the Series 4, which was not widely loved.

In 1973, Lotus decided to try and shed its kit-car image in order to concentrate on its more up-market models. As part of this plan, it sold the rights to the Seven to Caterham Cars. Caterham had been a Seven dealer since the very early days, and at this time they were the sole suppliers. After a brief period producing the Series 4, they reverted back to the Series 3 car, and have been making, and refining, this car since.

For a more detailed account of the history of the Seven, see one of the books on the subject.

2. The list

2.1. How do I subscribe to / unsubscribe from the Sevens mailing list?

There are two versions of the list; the following couple of sections will explain the differences. Note that all subscribers get all messages posted to the list, regardless of which version they subscribed to.

2.1.1. Normal (reflector)

The normal version of the list is a reflector; any messages sent to the list address are immediately forwarded to the other members of the list. At the time of writing, you would probably receive about thirty individual messages posted to the list per day.

2.1.2. Digest

The digest version of the list will collate a number of messages together before sending them out to the digest subscribers. At the time of writing, there are about thirty messages being posted to the list per day, which would result in one or two digest messages being sent out to digest subscribers.

2.2. Can I send binary files (including pictures) to the list?

No. Many list subscribers use fairly slow modems to download their mail. This means that your picture (which they may not want to see) will cost them significant amounts of time and money to download. In addition, some subscribers have a limited amount of storage for incoming mail, and your gigantic picture may cause their system to bounce back other mail.

If you have a picture that you think other list members might be interested in, you have two choices:

3. Buying a Seven

3.1. How much do they cost?

3.1.1. New

Anything from around GBP 10000 for a Classic in kit form to more than GBP 20000 for a fully-specified Vauxhall-engined car (peaking at about GBP 37000 for a JPE).

3.1.2. Used

You won't find a serviceable used Seven for much less than GBP 9000. At this sort of price you should find quite a few 4-speed, live-axle cars. From GBP 12000 upwards, you will start seeing De Dion cars. K-Series cars start at around GBP 14000, and Vauxhalls start at about GBP 16000.

Price seems to have more to do with condition and mileage than age of the car. Bear in mind that many Sevens live a pampered life, and a few thousand miles per year is probably average.

3.2. Where should I look?

The best places to look for a used Seven are in the magazines (Low Flying, Classic & Sportscar, Autocar, and Autosport are your best bets), and the specialist dealers. You may also get lucky at these web sites:

4. Body

4.1. Flared or cycle wings?

Sevens are available with two different types of front wing ("fenders" in American English).

The "flared" wing (or clamshell wing) is a long curved piece of glassfibre which stretches from behind the windscreen near the bottom of the car to the front of the car, covering the wheel. The cycle wing is similar to the mudguard on a bicycle - it only covers the wheel. On most cars, cycle wings are made of glassfibre; early Sevens had ones made from aluminium. Also on most cars, the wing turns with the wheel, so that the wheel is always covered; on early cars the wing remain stationary with respect to the body, so that when the wheels were turned, they peeked out from under the wings.

Which is best? It depends what your priorities are. Many claim that flared wings keep you drier in the wet, and that they protect the side of the car and the rear wings from stone damage, but they're not called wings for nothing. At high speeds they generate a lot of drag; sometimes it seems more like lift. Many people choose cycle wings because they think they are more stable at high speeds. This will probably only matter if you plan on spending lots of time on the track; road-going Sevens don't tend to spend much of their life at more than 80mph. The biggest reason for choosing cycle wings is also the most childish - you can see the wheels bobbing up and down, and turning left and right as you drive along.

4.2. Windscreen or aero-screens?

Contributed by Felix Klauser:
Most sevens come with a standard windscreen that allows such luxuries as wipers and sidescreens. The windscreen and sidescreens protect the occupants from debris thrown up by other cars, bugs, the occasional low-flying bird and the like. However, they do cause turbulence just behind the occupants (leading to unique hair styles) and add a lot of drag. Aero-screens (sometimes called Brooklands screens) are small half moon shaped pieces of tempered glass, one in front of each occupant, that are mounted in place of the windscreen. They drastically reduce turbulence and drag, leading to quicker acceleration and higher top speed. However, they provide virtually no protection from the above-mentioned flying objects and thus goggles or a helmet with eye protection are required. The aero-screens also don't allow the use of sidescreens or the hood, leaving occupants at the mercy of the elements.

4.3. Painted or bare aluminium?

Bare aluminium has to be looked after. If you want to keep the "grain", then Mother's polish comes highly recommended.

4.4. I want to fit an FIA roll bar. Will I need to change anything else as well?

The general consensus is that your existing hood will still fit, but you will need a new boot cover. This is because the braces on the FIA bar are thicker and come down at a different angle to the those of the standard bar. If you plan on getting the cross-brace (one end mounts to the FIA roll bar, and the other is fixed in the passenger footwell), then you will also need a new tonneau cover.

4.5. What sort of steering wheel should I get?

Firstly, you should bear in mind that if you go for anything smaller than the standard (12-inch?) wheel, then parts of the instruments on the dash will be obscured. There is usually a way around this, e.g. rotate the dials so that the important bits are visible, and swap the lights around so that the lesser used one (usually the ignition light) is obscured.

Contributed by Felix Klauser:
The choice is wheel is a very personal one. There are differences in diameter, covering material (vinyl, leather or suede) and thickness. The best thing is to see the different choices installed in a car and see what you like. One option is a removable wheel, allowing you to quickly remove the wheel a la F1. This is great for impressing your friends, eases getting in and out and is a useful anti-theft mechanism.

4.6. What type of seats should I get?

Contributed by Felix Klauser:
There are 5 types of seats for sevens:

4.7. What type of seatbelt should I get?

A seatbelt performs a number of tasks which may influence your decision of which ones to fit. Obviously, they must hold you firmly in your seat if you are unfortunate enough to be involved in a crash. You have to consider the chance that your Seven may end up upside down; it would be good if your belt held you in your seat, below the level of the roll bar.

One factor which is often overlooked is that a good-fitting seatbelt can improve your enjoyment of the car during normal driving. The braking and cornering forces which can be generated in a Seven can throw you around quite a bit if you are not securely strapped in.

There are four main types of seatbelt which are commonly used in Seven, and they all have their advantages and disadvantages.

5. Chassis

5.1. Live axle or De Dion?

This is a reply posted by Clive <> to a post by Brian Poulton <>:

>>Secondly, I have driven both live axle and De Dion cars and have the
following comments to make. On smooth roads, I wouldn't know which type of
car I was driving. On bumpy roads I would. I stopped using one of my
favourite routes to work as I damaged 2 sumps on a live axle car and I had
to slow down on the bumpy bits. Last week I tried the route again with the
De Dion car and it was a revelation. I was overtaking traffic where in the
live axle car I would not have dared travel at that speed at all.<<
Brian - thanks, I think you've described the essential difference. On smmoth
roads the differences will be minor - but when you get to the bumpy parts,
the de Dion will put its power down better and maintain its poise in a way
that gives the driver confidence to maintain a higher speed and pick his line
more accurately. A side effect, which some people apparently consider A Bad
Thing, is that tha car can also, if desired, be tuned to give a less
shattering ride, without giving up any handling (this last part should be in
italics !) - in fact, good handling on bumpy roads is so much a matter of
controlling wheel motion and dealing with the energy coming off the road,
that ride and handling go hand in hand. Personally, I think this is good news
- my idea of "being one with the car (and the road)" is that I should at
least be in contact with it (and the road) most of the time - easier to
achieve when it's not beating me up and throwing me around. Maybe I've missed
the point, but I thought the essence of the Seven was neat, precise, simple
and quick - if you want brutal for brutal's sake, don't you buy a TVR and a
chest wig, plus a copy of The Sun to read when you have to slow down in the
bumpy bits ?

6. Engine

6.1. What type of engine should I get?

6.1.1. "Official" engines Rover K-Series

The lightest standard engine, and many people say that this makes for the best handling car. K-Series engines tend to thrive on revs, which makes them the ideal partner for a Seven. The 1.6 SuperSport (as used in the Superlite) also has a decent power output (about 138bhp). Vauxhall 2.0l

Available with carbs (175bhp) or injection (165bhp), this is both the heaviest and most powerful of the standard Seven engines. Originally designed by Cosworth, it has huge tuning potential. Caterham claim 250bhp for the JPE engine, and Arnie Webb has 280bhp (!) in his Seven. Ford Crossflow

Old-tech engines (originally designed in the '60s), they were massively over-engineered which allows them to tuned to amazing levels. Ford only got 80bhp out of their version.

6.1.2. "Unofficial" engines

People have put all sorts of engines into Sevens - Cosworth turbos, Alfa Romeo, Rover V8s, with varying degrees of success. Be very careful buying a Seven with any sort of non-standard engine. Most of the Seven specialists know all about the common engines, but you will have a hard time finding an expert for that wacky engine of yours.

There is currently one exception to the "avoid at all costs" rule:

6.2. How many miles per gallon should I get?

6.3. Is it worth putting my Seven on a rolling road?

Contributed by Felix Klauser:
A rolling road session is good for tuning the engine for maximum power and ensuring that the engine is running correctly under load. However, real driving conditions are not always at wide open throttle and so what is good on the rolling road may still leave you with flat spots on the street.

6.4. Can I use unleaded petrol?

All new Sevens can used unleaded petrol. For the Rover, Vauxhall, and Zetec engines, this is perfectly safe - that's what they were designed for. Indeed, owners of cars fitted with a catalytic converter have no choice but to use unleaded. With crossflows opinion is more divided, with many people choosing to use 4-star leaded petrol.

6.5. My crossflow smokes - is that normal?

It depends how much. All the crossflows that I have seen smoke to some degree. Try comparing your car with another. If crossflow smokes a lot, or you think it is getting worse, then you should get it checked out. I've had cracked piston rings on two separate 1700 engines (one at 14500 miles, the other at 10500 miles).

6.6. How do I perform a leak-down test?

This message was posted by Kiyoshi Hamai <> to the lotus-cars mailing list, and is reproduced with his permission:

It's really pretty simple to build your own leak down compression tester...
The tricky part is getting an adapter that will screw into the spark plug
hole. It sounds like the hose compression tester you now have, assuming it
is a screw in type, will work. So, using that hose, attach a air pressure
gauge (0-150psi) and to this a means of attaching it to a air compressor.
Do put a quick release coupling between the gauge and the air source. Also
you'll need a valve between the gauge and the air supply. On the one I made
I adapted an old air blower nozzle to use as a valve. Your air source
should supply at least 100 psi. At sea level atmospheric pressure is about
14.7 psi, so 8:1 compression would be 118 psi. Once you've filled the
cylinder with air you want to cut off the supply of air so you can observe
the rate the air in the cylinder leaks out.
Now, rotate the engine so that the cylinder you're testing is in the
compression stroke (both valves closed). Replace the spark plug with your
tester, fill the cylinder with air (100+ psi) and watch the gauge and
listen. Here's the typical things you'll see...
1) Gauge falls slowly, no audible hisses - this is normal and GOOD!
2) Gauge falls fairly quickly, no audible hisses, no bubbles in the
radiator - rings maybe worn
3) Gauge falls fairly quickly, no audible hisses, bubbles in the radiator
- blown head gasket
4) Gauge falls quickly, no audible hisses - worn valve or valve seat
5) Gauge falls quickly, audible hiss - burnt or leaking valve, listen to
carb/intake or exhaust to isolate intake or exhaust valve...
6) Gauge never registers any pressure!!! BIG PROBLEM! Bent valve, holed
piston, holed cylinder, etc.
> I have an engine that has 50 psi difference between the best and worst
Some will say this is not much, but I'm of the school that 50 psi is
significant, down 25-35%. A leak down test will help you pin point the
cause. If there's lots of mileage on the engine it could either be valves
or rings. If head is fairly fresh and lots of miles, then it's more likely

7. Driving

7.1. Track days

7.1.1. Who runs them?

Seven Club, RMA, Trevor Willard Racing, Gold Track, Club 89, Club 96

7.1.2. What equipment do I need?

You will need a helmet in order to take part in any track day. For days organised by RMA for the Seven Club you will also need:

7.1.3. What else should I take to a track day?

Your car will be more highly stressed than it is when used on the road. As such, you should take spares and tools, but at a minimum you will need:

7.1.4. Anything else?

Generally speaking, your car will not be insured while it is on the track. Some people claim that their policy covers them as long as they are not timed. Best advice is to check your policy very carefully before relying on its cover for track use.

7.1.5. How safe are they?

Most organisers of track days take safety very seriously. Obviously, everyone drives in the same direction around the track. There is usually a rule stating that you must not overtake on the approach to a bend - sometimes overtaking is limited to specific places on the track. Sometimes, you are not allowed to overtake until the driver you will be passing has acknowledged your presence.

For all track days, you (and any passenger in the car) will have to wear a helmet. Usually, in an open-top car like the Seven, the organisers will insist that all helmets are full-face.

For Seven Club track days, you will also have to have an FIA roll bar, and a fire extinguisher. You must also have a race harness (4- or 6-point), which you would be well advised to have for any track sessions.

Many organisers will determine groups based on both the speed of the car, and the experience of the driver. This means that there shouldn't be any other cars flying past you at insane speeds.

Most track events will have the facility for you to go out with an instructor. Whilst you probably won't be able to hear a word he is saying through both your helmets, and the roar of the wind, you will at least be able to see the best lines for the bends, and where he brakes and accelerates.

Also, race tracks also tend to have more empty space around the tarmac than does a normal road, which is useful if you suffer from over-exuberance. Note however, that this is not always the case...

The following is contributed by Bryan Biggs.

I always say that it is worth remembering that there are two ways to make a car safe: "passive" safety and "dynamic" safety. A car like a Mercedes which is big, heavy and not terribly agile needs lots of "passive" safety (which it most certainly has). A car like the 7 which can brake very well and is extremely agile could often avoid an accident in the first place - "dynamic" safety. Which car would roll more easily - a Merc or a 7 ? On a winding road I'd feel much better driving a 7.

This in my opinion makes it a very safe car, be it on the road or track. In addition to this, a well constructed space frame should absorb any impact within the "compartment" in which the impact occurs if one of the morons out there does manage to connect your 7.

From experience it seems that the 7 spaceframe is unquestionably very strong and able to absorb such impacts.

The thing that worries me most is the fact that I'm so much lower than all the other cars on the road. It would be easy to be driven over by a truck! On the track this doesn't matter because none of us race 7's against trucks. (or do we?)

7.1.6. How much are they?

Most track days are around the GBP100 mark for a whole day. You will find the odd one a little bit cheaper; you will find lots that are quite a bit more expensive. As with all things, shop around for the best value.

7.1.7. Which tracks are best?

Cadwell Park is my personal favourite, and I know I'm not alone. For full details of all the UK circuits, see the Autosport Guide. Limited information is available on this web site:

7.1.8. Other useful track day info

If you get the track day bug, and you don't want to limit yourself to events organised by the Seven Club, then you should consider joining The Circuit Club. They publish a list of all the driving / test days at the UK circuits, and they often manage to negotiate special rates for club members. Contact details are given later.

Other clubs like Gold Track, RMA, Club 89, and 96 Club might be worth considering, but generally speaking, you have to go to a lot of their events to make it worthwhile joining.

7.2. Sprints / hill-climbs

Drivers are timed driving around a course one at a time. In sprints, the course is usually a race track, or an airfield marked out with cones. With hill-climbs, the course is usually a road up a hill (surprisingly enough). The drive usually lasts about one minute.

Depending upon what class you take part in, you may need some or all of the following:

7.3. Autocross (US)

This is from a message posted to the list by Brent DeWitt (

Since I currently compete in autocross in the US, I'll explain what happens
here. Autocross is relatively low speed. Generally the course is laid out
to keep speed below 50 to 60 mph for all but the fastest cars. The courses
are laid out in any available large area, such as a large parking lot
or unused airfield, with traffic cones forming sets of "gates". You 
generally get 3 to 5 runs at the course with each run being from 50 to 80
seconds in length depending on the available area. Timing is to the 0.001
second. Displacing one of the cones is a two second penalty. Cars
compete in classes determined by the car's capability as well as having
an "indexed" time overall. The courses are generally never the same on
two different occasions and there are no practice laps, although you are
allowed to walk the course at the start of the day. The Sports Car Club
of America has copyrighted the name Solo II for this form of competition.
No safety equipment other than a helmet is required. The car is inspected
at the beginning of the day for mechanical soundness.
Solo I is a higher speed event, generally held on a race circuit. It is
still one car at a time against the clock. It requires the same safety
equipment as road racing, so is less popular.

7.4. Road

7.4.1. I want to take my Seven out for a blast - know any good roads?

Check out Tony Boyd's home page.

7.4.2. Where can I hire a Seven?

Sevens are available to hire from the following UK dealers:

They all cost about GBP100 per day.

7.5. Can I drive it in the rain?

Although many Sevens are locked away in a dark garage at the first drop of rain, many people drive them in all weathers. The hood keeps virtually all of the water out of the car. If you don't use the hood, but can keep above about 50mph, then most of the rain will probably go over your head. On many Sevens, water will leak into the end of the footwell, where your feet go.

Needless to say, if you envision using your Seven in the wet, then cloth seats are not the ideal choice. Many people also do without carpets.

8. Parts cross-reference

This section lists equivalents for Caterham / Lotus parts. Where possible, these are the OEM part number, to make it easier to find them at your local Halfords.

8.1. Clutch cables

8.2. Rocker cover gasket

8.3. Spark plugs

8.4. Windscreen wipers

Someone told me that the wipers used on Sevens are the same as those used on Land Rovers, but cut down to size. Confirmation, anyone?

9. Miscellaneous

9.1. Is there a cheap way to measure the performance of my car?

There is a fairly cheap (around GBP100 +VAT) gadget called the G-TECH/Pro which allows you to measure 0-60 and 1/4-mile times, braking distance and time, G-forces, and horsepower. It contains an accelerometer and a timer - providing you start from a known speed (i.e. standstill), it can work out all the aforementioned figures from these two inputs.

There are two main downsides for Seven drivers: the device is powered from the cigarette lighter socket, and it sticks to the car windscreen. A Seven doesn't have a cigarette lighter socket; I have had some success powering mine from one of those 9V batteries with terminals on top, together with a lead with crocodile clips on one end, and a cigarette lighter socket on the other. The power cable coming out of the back of the G-TECH prevents its bracket from being mounted to a windscreen which is as close to vertical as that on the Seven. I mounted mine under the dash using the standard bracket, but replacing the suction cups with Velcro.

If you're interested in the G-TECH/Pro, check out the web site at US customers can buy (for USD140) with a 30-day money-back guarantee. UK customers can now get them from Demon Tweeks for GBP100 + VAT.

9.2. Are there any Seven models I can buy?

9.3. How much does it cost to insure a Seven?

See Brian Poulton's web page for a comparison of Seven insurance costs in the UK.

9.4. How can I make sure that my Seven doesn't get stolen?

I find that most of the criminal scum are more interested in what's in the car than the car itself, and here the openness of the Seven can be a boon - they can easily see that there is nothing to steal, without having to damage the car in order to get in and check under the seats, in the glovebox, etc.

You can't stop someone who is determined to steal your car, but can sure make it difficult for them. Here are some suggestions:

Who says they plan on driving your car away?

They don't have to nick the whole car.

9.5. The Prisoner

The Prisoner is a cult TV series, first aired in the late 1960s. A Lotus Seven Series II (registration plate KAR 120C) was used in the series. Some of the series was filmed at Portmeirion in North Wales. Allegedly, if you turn up in a Seven, then they will let you park your car inside the grounds.

For more details:

9.6. It gets too hot in the cockpit - how can I cool it down?

Most of the heat seems to come from the engine and the exhaust. The most common way of preventing heat from escaping from the exhaust is to cover them with insulating wrap. However, net wisdom has it that this can reduce the life of the exhaust.

One alternative that has received a few good reports is the metallic ceramic coating offered by Jet-Hot ( Here's a posting by Felix Klauser <>:

Jet Hot has informed me that they have 3 coating centres in the US and 1
in Austrialia but none in Europe. They will (and have in the past)
accepted parts shipped over from Europe for coating but they suggest
combining orders to save on shipping costs. For more info, see, send e-mail to, call on +1 800
432 3379 or send a fax on +1 610 277 5736. The account rep I exchanged
e-mail with is Brian Schlorff.

10. More information

10.1. Books

If you have problems getting hold of any these books, here are some Internet bookshops that list readers have successfully used:

There is also The Internet Bookshop ( I haven't bought anything from them, but their web site is pretty good for tracking down details of books that you are interested in.

10.1.1. Mainly Sevens

See also Jim Boone's web site at

10.1.2. Related topics

10.2. Clubs

10.3. Internet

10.3.1. Mailing lists

10.3.2. Web sites Mainly Sevens Related topics

10.4. Contact details

10.4.1. Seven specialists

10.4.2. Specialist dealers (new and used)

See also Arrowstar Racing, and Classic Carriage Company.

10.4.3. Engines

10.4.4. Parts (vintage and new)

See also Caterham Cars Classic Carriage Company, James Whiting.

10.4.5. Track events

10.4.6. Competition

10.4.7. Insurance

11. Glossary

12. To do

This section contains two types of question: those which I simply haven't had time to include in the FAQ, and those which I can't include because I don't know the answer.