What grade and type of fuel are you using for your older Lotus Seven or early Caterham 7?

[EdWills]

On 9/2/2024 at 5:07 PM, jbcollier said:

Getting back to the original question about what to run if you are in Canada.  Well, that depends.  What engine are you running?  And, in what tune is that engine?

I have a 69 Lotus Seven S3 with a somewhat modified 1600 Ford crossflow.  It has a stupidly-lumpy cam (not my idea), larger valves, and mildly ported.  I run premium rated 93 or 94 (rating on the pump in Canada) with no issues.  Ford crossflows have very good swirl flow and can run high compression ratios with few issues.  Lotus Twin Cams are not as good in that regard.

 

The issues with ethanol have little to do with running and performance.  The issues are with humidity, long term storage, and reactions with other materials.  I live in dry Alberta and do not fuss much but I will drain my tank and run the lines, pump and carbs completely dry before winter storage.

 

First, regardless of fuel you are running, if you can’t remember changing the fuel lines, change them ALL.  Use ethanol-proof lines and change them at least every five years, whether the car is run or not.

 

If you live in a dry climate, do the above two and relax and enjoy your car.  If you live in a humid climate, then you still need to do the above but also add a fuel additive specifically designed to stabilize ethanol fuels.  For winter storage, still drain and run dry your pump, lines and carbs but leave the tank full to the brim with the fuel + additive.  Come the spring, do not run that fuel.  Drain it off and run it in your commuter.  Only use fresh fuel in your Seven.

 

Lastly, ethanol and old, lined tanks do not mix well.  Getting tanks cleaned out and lined is getting difficult these days.  I’d recommend  either acid dipping the tank and properly repairing any leaks.  Or, fit a new tank.

Hello JB.  Great advice from you and the other correspondents - thank you all.  JB, I seem to have almost the same specification as you.  As I noted above, my original cylinder head was converted (by Holbay) for unleaded gas, with a practically brand new 1100 c.c. head used for the conversion. This was suggested by David Vizard in one of his books as there is more metal in the 1100 head that can safely be removed for porting without danger of grinding into the water jacket(s).  Holbay did a great job.  At the time, a number of conversions by other companies were being carried out and these were well documented in the U.K. car magazines of the time (Cars and Car Conversions for instance), detailing the conversions by such U.K. firms as Vulcan Engineering, Oselli, and Burton.  I have read, and I trust that the writers are correct in their assessments of Canadian fuel, that running a compression ratio of about 10:1 would be fine for the road.  Caterham 7 (Club) owners in the U.K. have also agreed with this suggestion. Their octane ratings are of course different to North America.  U.K. 98 octane may be close to our 94 in Canada?  I found a site on- line that compares the different methods of rating gasoline, so again, I trust that it is correct?  My question should have been more specific just dealing with the impacts of ethanol in the car considering that Lotus used rubber components available at the time for fuel filler hose at the rear of the car, a long black plastic tube from the Serck steel tank to the AC fuel pump, then more rubber tubing to the carb. The various carb options fitted would all have rubber (or synthetic rubber?) 'O' rings, seals etc., and the fuel pump has a rubber diaphragm inside.  I now have an alloy tank from the U.K. and I have read that aluminum alloy can be attacked by ethanol. Oh well!  A fuel filter is a very good idea in any Seven.  I purchased a unit that can be taken apart and cleaned from Mocal/Think Automotive in the U.K. I definitely agree with you that draining the fuel system for winter is a very good idea.  I do this every fall with our Craftsman (Honda) gas mower, and there has been no trouble with the tank and carb empty of fuel.  Oil change before first use in the spring.

So, thanks again, and happy motoring in the Edmonton area until the weather puts a stop to it.  Will

 

P.S. JB have you found the need to have your diff rebuilt, and can you recommend a company that is good at rebuilding Ford Escort diffs in Edmonton please? Cheers, Will

[jbcollier]

Are you in Edmonton?  If so, I can walk you through it, no problem.  
 

After I bought mine, I found a loose pinion nut and a howl.  So I bought and fit a replacement ring and pinion.  Quiet and oil tight now.

 

A good read on ethanol fuels:

 

https://www.amazon.ca/Classic-Engines-Modern-Fuel-Solutions/dp/1787115909?pd_rd_w=BPhpy&content-id=amzn1.sym.5ea934dd-1c86-463a-87ec-1025379fbf16&pf_rd_p=5ea934dd-1c86-463a-87ec-1025379fbf16&pf_rd_r=RB4YHRG13R98XBRA3565&pd_rd_wg=rUd8V&pd_rd_r=44e946ea-afa9-47d8-9a08-a290cfff2f56&pd_rd_i=1787115909&psc=1&ref_=pd_basp_m_rpt_ba_s_1_sc