Practically Classics Forum

Hello all
I have recently bought a Daimler 250 V8
I have been after one for ages and it is my first 'real' classic - I had a Rover P6 2200 SC auto to play with in the early 90's but it wasn't really 'that' old then and I had three Mk3 escorts but they were not really classics when I had them - just old bangers and boy were they bangers.

As for the Daimler - this petrol additive stuff, is it required for this car as I have several differing opinions at the moment?
If it is which is the best to go for and where do you get it from - is it a Halfords buy or is it an online only type thing, I had a nose around B&Q, the local garage and the supermarket and found lots of useless bits but not the additive stuff. the garage seemed to specialise in chocolate bars and crisps and had pretty much nothing for a car in there.
I am wondering if my old girl is running hotter due to the Unleaded or if it is just normal for a car of her age, I am still a raw recruit to the classic world you see :S

anyway HELP and thanks - Andy

Hi Andy, welcome to world of classic car ownership, enjoy it!
I'm sure the Daimler V8 had aluminium heads which will have valve seat inserts fitted & these should be ok to run with unleaded, but I may be corrected!
Your local motor factor should stock 'Lead Replacement Additive' if you do require it, I buy in bulk, it works out much cheaper.


John Simpson.

Another thought on this, besides the suitability of the head, is that most engines have some "lead memory" to the valve seats assuming it hasn't been rebuilt and scrubbed away which will protect things for a long time anyway.

Also, valve seat recession is generally reckoned only to occur under prolonged high RPM / heavy load situations, so assuming sensible driving it should be a very long time before any issues arise if ever. This is what the fraudsters marketing bits of alloy that you drop in your tank to protect the engine rely on.

That said, I still use an additive just to be safe, Castrol Valvemaster is my normal preferred choice, I also believe you shouldn't mix various types so if you choose one stick with it, if you change brands then run a couple of tanks of ordinary unleaded through before using the new brand.

Grease Monkey wrote:Hi Andy, welcome to world of classic car ownership, enjoy it!
I'm sure the Daimler V8 had aluminium heads which will have valve seat inserts fitted & these should be ok to run with unleaded, but I may be corrected!

This is absolutely correct. I know that some aluminium heads have reputedly been built with seats that are softer than those which are a match for the coefficient of expansion of the surrounding aluminium but - taking an example: The seat inserts in the Rover V8 heads - although some specialists reckon that only those built after a certain time are suitable - were all made from precisely the same tube stock and, in one of the labs at work (metallurgy) where the clean-looking chaps and chappesses with the white coats on are to be found, analyses have shown time and again that there's no difference between the seats in any two sample heads regardless of their years.
A couple of years ago, when I was still full time and managed to do my own experimenting with the fancy test gear after hours, similar comparisons were made between inserts from a variety of older, aluminium headed engines and among us we never yet found any case where the inserts were too soft. Valve differences yes, but the worst that we found with those would be burned seating areas on the heads of those exhaust valves so affected. That was more likely to be a result of weak mixture or similar issues and besides, valves are a whole lot cheaper than having inserts fitted which is quite unnecessary in the Daimler Hemis, the Rootes OHV engines in cases where they had the ali head, Jag XK engines, 2CV flat twins, all OHV Reliant engines from the 600 right through to the 850, Ricardo slant fours and the V8 version from Saab 99s, Dolomites, Stags, TR7s etc. O-series engines of all ages and capacities and many, many more. If the seat inserts had been too soft, they'd have fallen out on a frequent basis and those engines which did sometimes suffer from that fault, such as some (twin port especially) VW flat fours and earliest Imp units have either tried to eat their own valve seat inserts and been repaired or replaced since, or those were only rogue examples whose seats were taken from the wrong stock at the assembly stage.
I've covered over 200,000 miles in Dolomites, a further 200k or so in Reliants, 80k in a variety of others such as a Princess made the week after the O-series became the standard fitment, a VW1500 automatic, a variety of Renaults and Volvos with the Alloy-headed OHV "Sierra" series of engines and few of those cars had an easy life, none ever suffered from seat recession. By comparison, I wrecked the cast iron head of a miniMETRO on unleaded in under 4,000 miles . It was supposed to have come with a converted head and clearly hadn't.

Yes, your Daimler Hemi is fine for modern fuel, but use Super unleaded in that one if it pinks as I'm told they don't like the cheaper Premium stuff as much, that obviously being about compression ratio and ignition characteristics and nothing to do with seat to head metallurgical interfaces.

Well thanks guys, a lot of interesting and informative stuff in there.
I am quite new to this all and I am enjoying getting to grips with caring for a classic, I wasnt 100% on the fuel situation and didnt want to cause any damage if I could help it. Its also good to know that she may prefer Super unleaded - I have also found a Garage about 10 miles away that sells leaded 4 star, I assume this may do her some good to have a tank every now and then?

do you all find that your cars run a bit hotter on unleaded and if so is there a cure - or is it just something to live with?

There's absolutely no point in using the current type of leaded 4* as the base fuel is simply the bog standard Premium unleaded, the tetra-ethyl lead being poured in - while it is the ideal solution for soft valve seats - raises the RON octane rating to a level that's no higher than the (99 RON) Super unleaded.
Any issues surrounding unleaded causing hotter running are down to the base fuel's Benzine content and the corresponding difference in its volatility - vs old 4 star - which don't impact upon valve seat protection so it's only worth peeing the £2.00+ per litre up the wall if you run a car with an iron head and no inserts.
Save the leaded fuel for those who need the lead and buy Super at £1.48ish per litre, that'll suffice for the Daimler hemi. You could try a tankful of the standard "Premium" unleaded first though, if there's no sign of pinking on that then even the super won't be strictly necessary.

Unleaded fuel does burn hotter then old 4 and 5 star. It can cause problems - my car has the carbs directly above the exhaust manifold and the additional temperature can exaggerate fual vaporisation issues. I don't know the layout of your engine to know if you will suffer any similar issues but you'll soon find out!

I also have hardended valve seats in an alloy head so no worries there but originally mine used to run on 5 star so I ususally use Shell V-Power and sometimes an octane booster. Or at least I did before she came off the road for some TLC!

I have just been doing some prodding and poking and fixing with the assistance of my helpful and much thinner younger brother
We (ok he) managed to squeeze in and get the inhibitor switch changed over the other day during a torrential gale - non the less the new one is in and works a treat - no more hoping its going to start or not.
whilst underneath I sourced the brake fluid leak I noticed last week and I have a leaky front calliper on the drivers side - yikes, best get that sorted as soon as.
also a hole in the exhaust - only small but noisy enough - I noticed that it is pretty much hanging all the way from the flexi pipe to the back supports pretty much unsupported is that right ?
and.. after she was stalling all the time (an auto so odd) when driving her slowly on/off the drive I decided to bite the bullet and have a look at those scary duel SU's - with a borrowed Carbalancer and Colour tune in tow.
It was a bit of a failure though as one of the screws that move the wotsit in the jet assembly was flopping about all over the place whilst the other was solid.
after hassling father for a while we have decided that the spring at the bottom is either broken/worn or not there at all so some have been ordered on next day delivery (an extra £12 for the Royal Mail express service ) - last saturday and not here yet (tuesday) - useful that!
I am taking her to her first show in a field on Sunday with an exhaust that is far too low,carbs all over the place and a leaky calliper oh joy!!

Does the stress ever end guys ?

cybermat wrote:Does the stress ever end guys ?

fix the fault, get in, put your foot down and all your stress will be forgotten! (until the next time something breaks )

Lead memory..?? is there any technical information on this anywhere.?