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MG Midget and Sprite Technical - Lead Substitute and fuel types

Sorry to revive an old chestnut, but interested to know what others are doing.

I do not know whether the head on my Mk IV Sprite has been modified for unleaded and I don't want to lift it unless I have to, so I have been playing safe and using Wynn's Substi-Plomb but I have just found that they have discontinued it.

For the time being I've picked up a bottle of Carlube's lead substitute.

What are folk with un-modified heads using - if anything?

Have I just been wasting my money?

As most of the Sprite's outings are for hillclimbs I have been filling up with higher octane petrol - probably psychological more than actually performance enhancing in my case but the car seems to go well on it. As it won't be on the track for a couple of months and I needed transport today while my daily driver's in for MOT I filled up with ordinary unleaded. After each 15 mile leg of today's runs it ran-on briefly, something it hasn't done since I first got it and ran it on ordinary. Co-incidence or is it a timing issue or some other setting that's required with the different fuels? Many of my pre-event test runs are well over 15 miles with no running on.

Any comments would be appreciated.

Colin
Colin Mee

Colin,

Check with lawerance, he has a pair of good functioning lead balls he might rent you... (but that maybe considard illegal in some parts of the UK...haha)

Prop

Prop and the Blackhole Midget

On a serious note... id go with a popular established respectable brand name and avoid cans with vague names and big promisis printed on the can and I think you will be fine

Prop
Prop and the Blackhole Midget

If the ordinary 95 RON petrol causes running-on, then you are probably best to continue with the higher octane fuel. You could retard the spark a degree or two, but will lose a little horsepower.

As for lead substitutes, many say that the problem of valve seat recession is nothing like as serious as was first thought. You have two options. Continue to use a substitute and hope it is doing what it says on the bottle, or just use the higher octane fuel and monitor the engine's performance and valve clearances from time to time. If the tappet clearances close up, you may have seat recession occuring and then you can get the head converted to hardened seats.

Several different types of substitute are available from Opie Oils http://www.opieoils.co.uk/c-1241-lead-replacement-other-additives.aspx
Mike Howlett

Thanks for the suggestions, including the reference to Lawrence's spherical objects. I recall numerous magazine articles about their merits when unleaded first started to appear in the U.K. in the '80s. I steered clear of them then and I think I'll do the same now!

Thanks for the link Mike - several reputable names there to look out for. The factors that I usually use also suggested our local brew from Morris Lubricants, who seem to be pretty well thought of generally - sadly they didn't have any in stock.

I'll continue to keep a close eye on the tappets - there has been no need to adjust anything at the last few checks.

Cheers

Colin
Colin Mee

I have recently swapped motors; the new one having hardened oversized valve inserts, but previously I have used Castrol Valvemaster plus. It's on Mike's Opie oils link but I've also seen it in my local garage. I didn't have any seat recession problems. Of course I might not have had problems anyway...
The octane booster seems to help smooth running. You don't have to seek out Optimax or whatever 98 RON pumps either. It also seems to help running on my old Airhead BMW twin that gets thrashed and is susseptible to poor quality fuel.

Mark
M Crossley

If I recall, on some substitutes you only have to use them once every blue moon its not a constant continuous feeding

Considering you havent had to make any valve adjustment in a long time, id say your in great shape and can sleep well

Prop
Prop and the Blackhole Midget

It's not the missing lead you need to worry about, it's the ethanol!
Using super unleaded (except Shell apparently) as you do should sort the ethanol issue. There was a thread on here recently about it.
Lack of lead is IMO over stated unless you're doing a lot of miles. A friend has B and has run with a standard head and no additives for 7 or 8 years with out any apparent harm. If your valve guides begin to wear you can always exhange the head for an unleaded one then.
Jeremy Tickle

Ok, here's a close up picture of my balls. They don't work. You need the right type of lead in yer pencil. These balls, aint it.

As it happens, I've just rebuilt my spare engine using a standard unconverted head. I lapped the valves in, so I'm watching to see if the exhaust valves start to recess. So far, so good, but it's only done about 100 miles.

Castrol valvemaster. £12.75 inc free postage
http://www.ebay.co.uk/sch/i.html?_odkw=Castrol+Valvemaster+plus.&_sop=15&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.XCastrol+Valvemaster+plus.TRS0&_nkw=Castrol+Valvemaster+plus&_sacat=0

Here's a link to Castrol's data sheet on the stuff.
http://tinyurl.com/ocnsf3l

250ml treats 250ltrs. It's a bit expensive in the long run. Much better to have hardened seats fitted I reckon.






Lawrence Slater

I went to my local engineering shop to ask about the conversion and was told that because I do such a low annual mileage it was not worth the cost.I only do about 200 miles per annum. On the subject of substitute balls I noticed some on ebay and in the blurb it said that once installed(chucked in the tank)they would keep the fuel fresh during winter months. Comments?
I.M. CHRISTIE

As I said in my post.

Wrong type of lead. They won't deposit much if any lead into the tank. You need "Tetraethyllead".

If you want real leaded fuel, go here.
http://www.tetraboost.com/
http://www.tetraboost.com/info/faq/

Yup, if you're only doing 200 miles per year, I doubt you have to worry. But at that rate, the Tetraboost is worth it I reckon.
Lawrence Slater

As it happens, this has prompted me to get my finger out, and get a quote for getting my 1300GT head converted. So I've just rung Colin at Southern rebore. £140 quid to convert an A series head.

Comparing that to the costs of 4000 miles of the Tetraboost below, ---

http://www.tetraboost.com/
" Assuming 30mpg that's around 4000 miles of motoring for £120 plus £20.00 delivery to your door, almost anywhere on the UK mainland. "

----- conversion and the use of super plus unleaded seems a far better option to me. So that's the route I'll follow.
Lawrence Slater

never had a problem with any of my cars running on unleaded without additive. why pay for something that don't need doing. IF it damages valves in the long run then do it. i think its a load of cobblers.
bob
bob taylor

O.K> what about the balls, Are they a waste of tins aswell?
I.M. CHRISTIE

they sure are, a load of old balls.
bob taylor

I.M.

The lead balls are a gimmick to seperate your wallet from your cash... but on a postive plus note, using lead balls in your fuel tank (May/could) make your exhauste smell like fresh rain and roses :-)

Prop
Prop and the Blackhole Midget

I.M. if you do 200 miles a year and assuming you're now 20 years old and use the car until you're 80, that's 60 years or 12,000 miles of unleaded motoring. I'd bet your valve seats would still be ok.

Not sure about you or the rest of the car in 2075!
Jeremy Tickle

I was told today ( and think I may have been told the same thing before on here) that the original A series valve seats are not that hard, so are likely to be sugject to wear with unleaded. If the car has been used with leaded fuel, AND the valves haven't been ground since, then as long as you don't do high rev's, the seats won't recess. This is because there will be sufficient lead still coating the seats to protect them. But if the heads been off and the valves ground in, then the lead will have gone, and eventually the seats will recess.

I don't think it's balls at all. Valve seat recession does occur in some engines not designed to run on unleaded fuel. Our engines are old in terms of valve seat design.

This is an interesting read. http://tinyurl.com/o5jmhkj

Here's their advice for anyone not installing hardened or modified valve seats.

" Some auto enthusiasts own vintage or antique vehicles. These vehicles are unlikely to be operated under conditions that would induce excessive valve seat wear, so operating them with unleaded gasoline is generally not a problem if the octane rating is sufficient. In the event that someone has a concern, several options are available: (1) Operate the vehicle only at speeds lower than 60 miles/hour (96 kilometres/hour); (2) Install redesigned valve seats when the engine is rebuilt; (3) Use fuel designed to replace leaded gasoline, if available; and (4) Use one of several anti-valve wear additives that are commercially available at filling stations or automobile parts and supply stores (note discussion
in Section 3.5 below). "



Lawrence Slater

This thread was discussed between 26/05/2015 and 27/05/2015

MG Midget and Sprite Technical index

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