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-   -   Unleaded head or not? (https://madabout-kitcars.com/forum/showthread.php?t=3449)

donnysoutherner 5th April 2012 20:39

Unleaded head or not?
 
My donor is a 1300 Spitfire but the previous owner (who abandoned his project) was unable to sy whether the head had been converted to unleaded or not. Is there any way to tell? Other than filling it with unleaded and seeing if the valves burn out!

seanick 5th April 2012 22:52

I have had a tuned morris for 16 yrs. Probably done 20k miles. When I got it I stuck in the tank one of those fuel cat things. Recommended by a morris restorer, they are silver balls of tin or lead which are in a small gauze. You pop them in the tank and they do good things to the fuel, and save your valves. Available on EBAY etc.
They seem to work as I have had no valve probs, and I boot it a fair bit, but ni motorway miles.
I would leave it, and sort it if its a problem later. Plenty of other things to do!

Mister Towed 6th April 2012 08:53

I'm in the same boat: my Vitesse was sold to me as having had a recent engine rebuild with unleaded head but I've got no way of telling.

The way I understand it is that the lead dampened the hammering the valves give the valve seats and it's the seats that are hardened on an unleaded head.

Running an original head on unleaded will cause the valves to rapidly wear out the valve seats causing a loss of compression and reduced performance. Please feel free to correct me if I'm wrong but it shouldn't lead to the valves burning out and catastrophically damaging your engine.

I'm planning to run mine as is or I might just drop one of those silver ball do-dads into the tank just to be on the safe side.

Having said that, I would be interested to know if anyone can tell us how to check to see if hardened valve seats are fitted? :neutral:

Straight Sixer 6th April 2012 09:48

The lead issue comes round in our Jaguar (erm... club?) every now and then. The reason valves might in theory burn is because recession in the seats will cause the valve clearance to reduce then dissapear. then the valves don't close fully and that's when they are supposed to get burned out.

Don't forget the the USA has had unleaded type petrol for donkeys years and Jaguar for one, have been fitting hard valve seats as standard since late 1967!

Maybe Triumph did the same, does anyone know when if they started fitting hard seats?

The Jag lot swear by the additives like Millers VSP and stuff but for me its too dear to use in every tankful so I splash a bit in the MK10 every 3rd tank or so.

Most reckon that if you're not doing 20,000 miles a year of motorway driving, you won't do any damage to valves, but set the ign. timing so it don't pink.

Len.

davecymru 6th April 2012 17:57

This is weird as I'm in exactly the same situation.

There had been so much done to my donor i've got no idea if it had an unleaded head or not (everything else seems to have been tinkered with!) so at the moment I'm just using the additive in every tank, although as has been said, it is quite expensive so if this ball thingy is a cheaper alternative then i'll gladly give it a go. Anyone got a link to one?

donnysoutherner 6th April 2012 18:12

Looks like the ball thingy is the way forward!

Mister Towed 6th April 2012 20:14

Could always fit this:

http://www.ebay.co.uk/itm/TRIUMPH-VI...item4ab626fb88

seanick 6th April 2012 21:36

fuel catalyst
 
Try EBAYing fuel catalyst. £26 for up to 2000cc.

MoriniMan 6th June 2012 22:02

Quote:

Originally Posted by seanick (Post 29083)
Try EBAYing fuel catalyst. £26 for up to 2000cc.

These things are a con. There are only a few vehicles that if running well on leaded fuel would then give trouble on unleaded. If you've ever tried to recut valve seats in cast Iron heads you'll know that they ARE hardened. They're work hardened by the hammering action of the valves over the years.

When unleaded fuel came in, quite a lot of the classic car mags ran 'tests' to show how much of a problem it was going to be. They usually had a head reconditioned, cutting through the work hardening and of course got seat recession.

Seat recession happens when the valve is running hot enough and the seat pressures are high enough that micro forge welding occours. You're really not going to have a problem with a low revving side valve (many of which will have been designed to run on pre-leaded fuel anyway). Some engines had very strong valve springs and ran their exhaust valves hot, even in the days of 5 star fuel and they may well need a seat conversion.

My advice has always been to wear out what you've got now before spending any money. By all means keep an eye on the valve clearances for evidence of them closing up and perhaps even put a bit of cash aside each month for the eventual unleaded exhaust seat conversion. I know of peole who've been doing this ever since leaded fuel became difficult to source. Some of them have bought a couple of cars with the money they've saved up.

My Morini motorcycles have seat inserts, but are very definitely pre-unleaded and the seats are only a good Iron grade. Some people are using a fuel additive, but I just stick to mostly V-Power. At the Club track day this month I'll be pulling 10,000 rpm at the end of the main straight as usual on the little pushrod V-twin as I've done for the last eight years. I do check the clearances from time to time, but I rarely have to actually adjust them.

If you do have a conversion done, go for a Bronze type seat material. They conduct heat very well, so they keep the valve cooler, they're an incompatible metal, so resist the micro welding and being relatively soft make valves last longer anyway. Berylliam Copper used to be the best seat material, but Berylliam dust is a known cancer causing agent so there were heath issues involved in the machining process. Trojan from Collumbia Metals (they also produce Colsibro popular for valve guides) is the modern choice. Stainless steel valves are not compatible with Iron guides and you risk a seized valve. There are two piece valves available and also ones with plated stems, but bronze guides are really the way to go.

Take a look around on Guy Croft's website/forum for more information.

davecymru 7th June 2012 08:12

What an excellent and well written reply, many thanks!

seanick 7th June 2012 08:32

Blimey!

oxford1360 7th June 2012 09:24

In follow-up to MoriniMan's great answer, I was once told by a very experienced builder of old race engines that the quickest and easiest way to convert your Triumph to unleaded is to go to the station and fill-up with the stuff.
He had done in excess of 20k miles like this and had not adjusted clearances any more than he would have done in the past.
I was planning to do exactly this.........but I had the opportunity to pick-up a new head at a good price......and it has been converted. It'll probably give me endless trouble!

tlrtone 7th June 2012 19:58

Quote:

Originally Posted by davecymru (Post 31647)
What an excellent and well written reply, many thanks!

I think we have found ourselves the Sammio "not-a-club" Tech officer! :humble:


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