Unleaded Petrol, Should I Worry?

[sedmtg]

I'm sure this isnt the first time this has been asked, but I'm new to the club.

My '76 Cav coupe has done about 3000 miles on unleaded, with additives - I cant remember which ones as its been garaged for most of the 22 years I've owned it, but I did find 2/3 bottle of redex in the boot so clearly I've used that at some point but its likely I've used something else too. I'm sure this isn't the best additive to use but as I was a student the last time it was on the road (1997)this was probably the one I could find locally - and afford.

I'm really wanting to get it back on the road again for a few months but I'm getting paranoid about fuel. Its done 68k and Im guessing that at least 65k of these were done on proper 4 star. should I be worried?

I've not touched the engine as this appears to be working perfectly and is quiet (as they go), except for dumping the Zenith carb for a weber 32/36 and the obligatory 2" exhaust (PMC) .

I'm guessing there must be some poeple that use their 16/19/20 CiH Mantas or a Cavaliers on a regular basis and I'm wondering if anybody has any advice regarding unleaded fuel, and any precautions, or additives used, or any problems you've had.

Any ideas on the cost and what work would be required to the head to make it truely unleaded? If I do work the head, is it worth doing other work, like boring the block to 2.0/2.2 and finding a suitable head?

I'm wanting it to look as standard as possible under the bonnet at this time, tho I may consider biting the bullt and going for something differant with injection if i can get a 5 speed box that fits wihout too much work.

Thank you

Mark

[1900SR]

With additives the general advice seems to be use one and stick to it. I use Castrol Valvemaster Plus which has an octane booster as well(although mine only does a few miles a year). If you drive the car hard then I think there's more chance of damaging the head. There is a school of thought that says if you're prepared to have the head work done, run it until it shows signs of valve seat recession then get it done. If you can get a head from a later GT/E then this will be unleaded ready.

[Rapierdave]

Hi Mark

I use Castrol valvemaster myself, i also only use Super unleaded normally Shell V+ as normal unleaded contains an additive which can cause older fuel lines & gaskets to fail.

I also have found that normal unleaded at 95 octane has caused pinking on some of my cars where as Super unleaded at 97 octane or 99 octane for Shell V+ seems to work better.

Obviously there is quite a price difference with Super unleaded but a i only use my car for weekend use in the summer it doesn't bother me that much.

Apparently Tesco Super unleaded is also 99 octane & is about the cheapest Super unleaded around.

IMHO leave it standard Mark, maybe convert it to 5 speed, standard Cavs & Manta's are now getting thin on the ground.

[lamchop77]

Mark

The thing to watch for is the tappet gap closing up, shows your getting valve seat recession. I used to use Millers stuff VSP was good for road motors and CVL for competition stuff both had octane boosters in VSP was at 4 star level, CVL used with super unleaded got you to near 5 star!! You shouldnt have any probs using these.

If you do get probs with recession of the valves the fix is hardened valve seats fitted, usually just to the exhaust valves. Cost is prob about 150 all in done for a 4 pot head, plus gaskets. you will also need to retard the timing for the lower octane rating, usual setup 4th on a steepish hill and boot it to the floor, retard the timing so its just starting to pink.

Additives are fairly expensive, if you have done 3000 miles and your car is averaging say 25 to the gallon then you will have used 105 quids worth of additive. Personally i'd get the work done

HTH

Chris

[plumster]

Castrol valvemaster, an in-line lead converter thingy (God knows what this does if anything) & the highest octane unleaded from wherever I put fuel in.

[sedmtg]

Hi Guys,

Many thanks for your advice - looks like the castrol valve master is the favourite!
My dates were a little wrong in my initial post, I got the cav on the road in 1997 and did about 500miles, the remainder, 2500 miles will have been done from 2000 onwards so unleaded and additive of some description.

Engine is still very quiet so I dont think there's any damage done yet due to recession and I'd like to keep it that way, hence the question.

I forgot about it, but I have a 'fuel cat' fitted too. I cant remember the make/model and the paperwork appears to have vanished after several house moves, but I remember it being an inline tube filled with 'tin balls'!!! Whether it does anything I dont know but I remember it had a lifetime guarentee for what thats worth without the paperwork, but i dont want to gamble my engine on it.

SR1900 - If I understand you correctly, if I bore the engine to 2l, the GTE head should fit and is unleaded?

Will this work well with the Weber, or does it really need injection, and I understand this has hydraulic tappets - would my 1900 block feed these, or would I need the 2l block?

Would the 5x speed box bolt onto my engine and fit my floor, or would i need a new hole cutting for the gear stick and maybe GTE prop and back axle? or is this atraight swap?

Sorry for all the questions, but you guys have probably done all this before and know the right answers!

I too have come to the conclusion that my R-Reg 76 cav is prob best left standard, but there were a few mods I made in the 90's,

It gained a few mods such the 32/36 weber, pipercross filter, 2" exhaust, Manta GT bronze tinted windows, GT boot spoiler, GT alloys and the chrome trim was replaced with the black GT trim. chrome bumpers tho the rear is looking a little shabby. I did keep the the rostyle wheels tho which only need stripping, cleaning, painting and booting.

I stripped my bro's 18GT for parts in 1996, hence all the GT parts - my mum gave me 48 hours to get it stripped and off her driveway! Unfortunately, I dont have all of the original bits I took off because I didnt have space to keep them and didnt consider how rare those bits would be now.

oh and as a treat, I bought and fitted a set of adjustable lowered Spax springs/shocks but these are bit too hard and makes it feel like there's no suspension at all. you feel every pebble you drive over which isnt good on Sheffield roads!

In my defence, I bought it in '91, on its way to the scrappy from its previous owner who only used it as a cheap run about til its MOT expired, with the intention turning it in a 400 replica - as you do when you're 19! luckily I didnt have the time or facilities, or cash to do this. Instead I started a preservation exercise and stripped it, patched it, waxoyled it and occationally put it on the road for a few months every year or two with the intention of restoring it properly when I grew up when I'd obviously have more money to spend on it! Now I'm older, but still waiting for the money to spend on it, however I'm itching to take it out again for few months.

Thanks

Mark

Edited July 3, 2013 by sedmtg

[mantadoc]

If it were mine, I would run it till it died on unleaded 5 degrees retarded and then change the head or put a later engine in, both are cheaper options than having head work done, but it's not mine so not recommending that.

No idea what CC your engine is though.

Some reports say a car ran for years on leaded may have as much as 25K miles of "lead cover" in the fuel system. My wife used her Kadett C on unleaded and got through 5 engines in 100k+ miles, but two of those were because there was no oil in them so 30K an engine say.

Finally, unleaded fuel is still sold. You just need to look up where some of the 1million gallons a year for classic cars is sold. http://www.lacors.gov.uk/lacors/upload/8268.pdf

(No idea if this still exists been a while since I looked)

[sedmtg]

Hi Mantadoc,

Its a 1900cc - original engine with 4x speed box

Many thanks for all the advice... I think I'm going to err on adding something, probably to shell V-power and try to keep it running as long as long as possble. If it starts to have problems I'll have to think about it again..

Mark

[spiney_norman]

Probably did about 20k miles in my coupe with unleaded, never noticed any issues but that's no guarantee.

[smiffy220]

I had been using standard unleaded in mine for the last couple of years, now tend to put in super unleaded. Not been using additives and no signs of any damage as yet. Probably done about 4000 miles since I've had it, but I tend to keep it under 3000 revs!

[MicsManta]

I run my 1985 manta gte on super unleaded with castrol valvemaster plus ( with octane boost) like most of the other members on here, i have also retarded the ignition timng about 2 degrees from standard as well. i have been driving the manta for about 5-6 months now nearly every day, the other days i drive my fiat 126 1987 (I have been diving the fiat with that comination for 3 years) on the same combination and both of them i drive hard (normally between 5000-7000 rpm every gear (obviously not in traffic or around town) and both cars the engines run perfictly. with the fiat i have had the head off and the valve seats were not damaged at all.

[mantadoc]

I run my 1985 manta gte on super unleaded with castrol valvemaster plus ( with octane boost) like most of the other members on here, i have also retarded the ignition timng about 2 degrees from standard as well. i have been driving the manta for about 5-6 months now nearly every day, the other days i drive my fiat 126 1987 (I have been diving the fiat with that comination for 3 years) on the same combination and both of them i drive hard (normally between 5000-7000 rpm every gear (obviously not in traffic or around town) and both cars the engines run perfictly. with the fiat i have had the head off and the valve seats were not damaged at all.

some if not all 1985 Mantas have haedened valve seats to run unleaded anyway so you might be wasting your money. I would check your fiat two because on that year might well be the same..

Both might be fine regardless of your other steps

[MicsManta]

to my knowlege all the air cooled 126 had soft valve seats. as or the manta unless there is a easy way to find out weather it is fine to run it on unleaded, i think it is better to be safe than sorry especilly the way i drive it.

[spiney_norman]

If the head has P2E stamped on the side of it above the plugs it's fine!

[MicsManta]

thanks spiney_norman i will have a look.

[cam.in.head]

all 1.9 engines dont have unleaded valve seats unless someone has done them. as spiney norman says check if the head says p2e or p2.this will mean someone has previously put a 2 litre unleaded head on. you can fit an unleaded head to a 1.9 no problem but use a 1.9 head gasket & try preferably for a gte head(p2e)as this MAY give you back a little of the compression ratio lost by going up in combustion chamber size(93-95mm)or obviously just run it as it is untill you notice any change as the head would have to come off then anyway........