Cautious Hello

Ah yes, that was what my previous Imp died from. I sold it because I didn't know what a head gasket was, let alone what to do with it.

Reply to
Fran
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Um. Sorry, you'll have to explain that in simpler English.

Reply to
Fran

Meaning...?

Reply to
Fran

Hmmm.

If it needs explaining further, then just take it as read that it'll be fine on Super Unleaded, because a partial lobotomy is going to be needed to dumb it down ;)

I have assumed that you already understood (in theory) valve seat recession to have asked the question in the first place.

Richard

Reply to
RichardK

Thanks a bunch.

What question? I asked if it would need an additive in the fuel. I can't remember exactly when 4* was phased out, but I do remember that there were all sorts of discussions about modifying cars in order that they might run on the newfangled unleaded petrol. I didn't understand it then and I don't now; however I do know that I can't get 4* petrol any more, so I wanted to know if I needed to get a bottle of wotnot to add to the tank. All the subsequent posts about alloy heads weren't mine, except the one wherein I said that I believed it to be the case that the Imp had one. What this means in terms of fuel I haven't the faintest idea - that's one of the reasons I looked for a geriatric car NG, so I could learn a bit about what I'm taking on. I fear you have me at a disadvantage, for I have not the faintest idea what valve seat recession is - but I'm willing to learn if someone would care to try explaining...

Reply to
Fran

Air cooled Imp? Did you run it dry?

Reply to
Dean Dark

Okay. I'm ratty about the number of snipped-for-privacy@privacy.net trolls lurking about the place.

The reason you shouldn't - as opposed to can't - use unleaded in many older cars is that an iron head with whatever (steel derivatives, I think, is most common) valves relied upon the lead as a lubricant - it prevented the valves from eroding the head as they opened and closed.

The solution to this problem for people in the US where unleaded was mandatory a lot earlier was to use hardened valve seat inserts - a collar that fits into the cylinder head, and provides a much stronger surface for the valve to close against. No need for lead.

'Alloy' being softer than iron needed this protection pretty much from day one (alloy in this case just being a generic term for an engine made out of an aluminium alloy - an engine made of an alloy of other materials could be pretty tough).

VW Beetle engines dating from the 1930s can run on unleaded. A lot of pre-war engines can, since lead was added to fuel relatively late on (I want to say 1920s, but I wouldn't assume that to be right). And a lot of Japanese cars which were allegedly not able to run unleaded can do so just fine - it's simply the timing that has to be adjusted due to the lower octane. Basically most cars from the 80s aside from backwards British machinery was capable - in terms of VSR - of running unleaded fine, but was optimised for leaded fuel and lacked the technology to adjust for lower octane.

I hope you've got a good specialist to look after the Imp though - no offence, but running a classic car with so little mechanical knowledge is really asking for trouble, or at least, avoidable catastrophic engine failure by the side of the road.

Richard

Reply to
RichardK

No.

That simple enough?

Reply to
Ian Dalziel

One for sale here...

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Reply to
John & Lisa

I have owned an Imp and the Sunbeam variant. That was 20 years ago, but I still have some of my marbles, so might be able to chip in now and again.

Jim

Reply to
Jim Warren

My sunbeam was used as an auxiliary brake by a learner driver. I regret that too, since I was enjoying that car.

I found myself happily thundering up a 1 in 9 in thick snow (the best car I ever drove for traction in snow, by the way) and discovering that when I turned the wheel it didn't want to go round the bend.

Likewise the M5. However, it was an air flow thing. Go a bit slower, or a fair bit faster and cooling air started to go through the radiator again. Going faster in the standard Imp required a decent downhill, but the Sunbeam was 15mph faster than the standard Imp on the flat.

September 1970 to August 1971

buy the additive?

Don't waste your money on a lead wotnot. Almost as effective as snake oil. (I bet I am not the only one to say it!)

The Imp has an alloy head with hard metal seats inset. I think the head will be OK on unleaded petrol. BUT, I don't think the metal the valves are made of will survive long with undoctored unleaded, so if you are looking for a long and trouble free life, I would add one of the additive liquids to the petrol each time you fill up. Castrol Valvemaster and RedLine Lead Substitute seem to have the best following in this NG. If you have bought an Imp Sport, TetraBoost will be your best bet though.

The conventional wisdom is that if you think a car might be OK on standard unleaded then try it, and only if you have trouble do you need to do anything else - which is normally to pay for an unleaded conversion. However, an Imp has its valve timing set by shims, and the owner is advised to check clearances every 30,000 miles and reset them every 100,000. That sort of constancy suggests that it is best left undisturbed. If you change the valves, will you be able to obtain exactly the right shims to get the clearances right, and then to redo them after the valves have bedded in? And you have to be very careful with a torque wrench to replace a head without getting head gasket problems in the future. And get ALL the air out of the cooling system to avoid hot spots in the head.

It can all be done, but a few chemicals in the petrol tank can make sure you don't have to bother. It is your car, and your choice.

Jim

Reply to
Jim Warren

You didn't sell it to John for £30 did you?

Jim

Reply to
Jim Warren

No, I sold it to someone who would appreciate it and treat it to some TLC.

Reply to
Fran

Fair enough. I got ratty about the number of Usenet-generated spam emails I got when I used an unmunged address in the headers. Is this one any better? It's even translatable for those who really want to get in touch.

I see. OK, so with the alloy head the lead isn't necessary as a lubricant. I assume some sort of lube is still needed though - or is there less damaging friction between the alloy and the valves?

OK...

And heavy, I should think.

I learn really fast when I need to, usually by my mistakes :-)

In treating myself to an Imp I'm living a dream I had ever since I sold my last one. If it turns into a nightmare - well, at least I'll have given it a go, instead of just sitting on my backside thinking about it. But yes, I do have a couple of friends who know far more than I do and will help me a lot, but they're not all as local as I'd like so I've got to do a lot on my own.

Reply to
Fran

Absolutely thanks, and even more so now that I know and understand the reason.

Reply to
Fran

Pardon?

Reply to
Fran

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I think the boot lid was left open.

Reply to
John & Lisa

Ain't air cooled. If you don't get a radiator with your new one you've been ripped off.

Reply to
Ian Dalziel

Imps have a conventional water cooling system unlike the Beetle & IIRC original VW camper van engines which are directly air cooled.

Reply to
Dominic Sexton

You sure about that? I know it's a long time ago, but I'm sure my old Imp was air cooled. Or am I just having a middle-aged moment?

Reply to
Fran

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