will it run on unleaded fuel

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will it run on unleaded fuel

Post by kevfletcher » Thu Dec 15, 2016 12:30 am

sorry if this has been covered before, being new to Scimitar ownership i am still learning. when i introduced myself i told you all that my son and i had been given a non running 1976 GTE well we now have it running but the big question is do scimitars run on unleaded fuel or do the heads have to be modded and if they have to be modded is there an easy way to see if this mod has been carried out
thank you
Kev Fletcher



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Re: will it run on unleaded fuel

Post by rebel alliance » Thu Dec 15, 2016 2:55 am

It will be ok on unleaded.I think you would have to remove a cylinder head to check the valve seats.Personally i use lead additive at £2.30 a bottle treats 50 litres......j



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Re: will it run on unleaded fuel

Post by peter freeman » Thu Dec 15, 2016 7:29 am

We ran our 5A on unleaded for 130,000 miles before we sold it - the engine had done 215,000 miles - no additives used or changes to the timing. Unless you plan on running at high rpm all the time it should not be a problem - the mod is fitting hardened valve seats. Worth doing if you are taking the heads off for any reason but otherwise just leave as is IMO.



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Re: will it run on unleaded fuel

Post by toomanysabres » Thu Dec 15, 2016 8:33 am

What he said ^^^^!!
I would add that the money saved by not using additive will easily go a long way to pay for hardened seats should they need doing in the future


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Re: will it run on unleaded fuel

Post by rebel alliance » Thu Dec 15, 2016 10:29 am

If it helps the maths are 30.000 miles of driving at 25 mpg =£300 of additive at £2.50 for 50 litres treatment, i have no idea the cost of fitting valve seats or any garage costs for the work .



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Re: will it run on unleaded fuel

Post by Nigel Clark » Thu Dec 15, 2016 10:50 am

rebel alliance wrote:If it helps the maths are 30.000 miles of driving at 25 mpg =£300 of additive at £2.50 for 50 litres treatment, i have no idea the cost of fitting valve seats or any garage costs for the work .
I recently had a Triumph 6 cylinder head converted to unleaded plus new valve guides, valves refaced, valve seats recut, a light skim and assembled with new valve springs for £400 + VAT, done at a local machine shop who specialises in classics. I would imagine a pair of V6 heads would come in at a similar price.

I only did this because I was rebuilding the engine and the head was off. It had run the previous 20,000 miles on super unleaded without additive and there was no sign of serious valve seat recession. Both the Triumph engine and the Ford V6s have cast iron heads so would expect them to react in a similar way to unleaded.

My advice would be to drive it on super unleaded and no additive. Check the valve clearances regularly (say every 3-6,000 miles). Only convert to hardened valve seats if:

- The exhaust valve clearances start reducing, indicating recession, or...

- You need to take the heads off for some other reason.


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Re: will it run on unleaded fuel

Post by littlestwoo » Thu Dec 15, 2016 11:06 am

Agree with all above.

I think the fuel octane rating is as much an issue as valve seats. Putting the hardened seats to one side, you will still have to do one of 3 things. 1. Retard the ignition 2. Run on superunleaded 3. Use an octane booster. 2 and 3 have cost implications so my view is you might as well just add an octane booster plus lead substitute. If I was rebuilding an engine I would probably have the seats done at the same time.


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Re: will it run on unleaded fuel

Post by Scimher » Thu Dec 15, 2016 11:22 am

...Agree that additives aren't necessary - unless the car is leading a hard life ie. high mileage, lots of towing, motorsport, high speed autobahn trips etc. etc. I'd also go so far as to say that 'super' isn't necessary...(yet it is in my 1300 Dolomite-engined Herald!) The Scimitar 'guru' Dave Mac. said to me, once, that the 'Essex will run on anything' & it does seem a very amenable engine from that perspective...



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Re: will it run on unleaded fuel

Post by rebel alliance » Thu Dec 15, 2016 11:49 am

All very sound advice my reasons for useing lead additives are the very low use of my cars,a few hundred miles a year and the fact the engines are rebuilt or low mileage units and it would be a shame to damage the seats for a few pence a gallon extra .



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Re: will it run on unleaded fuel

Post by Old and Slow » Thu Dec 15, 2016 1:58 pm

I use the Millers additive as "approved" by the FBHVC, can't tell whether it makes any difference, but I get "peace of mind" (placebo effect?).
BTW well done on getting the Scimitar up and running; I'm sure you must both be well pleased.
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Re: will it run on unleaded fuel

Post by Elizabeth's dad » Thu Dec 15, 2016 2:58 pm

I gave up with additives years ago and never noticed any difference; same thing with fancy fuels, it runs perfectly at original ignition timing on supermarket petrol. I don't drive hard/race/tow(any more) which might affect things and my mileage is very low.


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Re: will it run on unleaded fuel

Post by CNHSS1 » Thu Dec 15, 2016 4:13 pm

Almost all the compies have suffered valve seat issues with unleaded in Essex engines, unless run with additives or fitted with harder valve seats BUT their usage isn't gentle road miles, they are pushing the engines although most are trailered so little real mileage. When pushed hard, unleaded does raise head Temps significantly over 4 star, which may account for why the compies suffer more than most.

Millers CVL along with Shell V Power fuel is the best combo it would seem. The fuels a constant, runs cleaner due to detergent levels and high octane (highest pump fuel on the street) unlike supermarket fuels which are at best variable. The Millers CVL also adds a bit of anti knock so you can advance the timing or at least not have to retard it.

Hope that helps :-)
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Re: will it run on unleaded fuel

Post by Nigel Clark » Thu Dec 15, 2016 7:00 pm

CNHSS1 wrote:Almost all the compies have suffered valve seat issues with unleaded in Essex engines, unless run with additives or fitted with harder valve seats BUT their usage isn't gentle road miles, they are pushing the engines although most are trailered so little real mileage. When pushed hard, unleaded does raise head Temps significantly over 4 star, which may account for why the compies suffer more than most.

Millers CVL along with Shell V Power fuel is the best combo it would seem. The fuels a constant, runs cleaner due to detergent levels and high octane (highest pump fuel on the street) unlike supermarket fuels which are at best variable. The Millers CVL also adds a bit of anti knock so you can advance the timing or at least not have to retard it.

Hope that helps :-)
Craig
I think this sums it up...

If your Essex is to be driven hard (or many other classic engines), valve seat recession will soon be a problem with unleaded fuel. But for everyday driving, where a 70mph cruise in o/d top is just 2,500rpm, the old cast iron valve seats will last a long time.


Nigel



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Re: will it run on unleaded fuel

Post by efi_sprintgte » Thu Dec 15, 2016 7:47 pm

I hammer the crap out of my classics, be it track.. towing or keeping up!!

Plus 1 for CVL plus Vpower


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Re: will it run on unleaded fuel

Post by kevfletcher » Thu Dec 15, 2016 10:15 pm

thanks a lot for all your informative reply's, pretty much along the lines i was thinking. i have several older cars (MG midget, Morris Minor to name a few) and i have never used additives in the fuel certainly the moggy you can easily get exchange heads with hardened valves fitted for around £250 but i have never really felt the need to go down that route. my older vehicles are strictly weekend toys so do not rack up heavy millage. next job is to try and sort out the coolant hoses on the scimitar as they all seem to be rotten and perished. but the whole very impressed with are freebie even the chassis seems fairly rust free just minor surface rust



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