Forum Replies Created
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I have now rebuild my engine and installed new camshafts from the Club (with more rounded cams as opposed to my previous camshafts which had very flat lobes – see the picture I uploaded earlier in this discussion). Everything is now perfectly set with the recommended 24 degrees valve overlap and the problem of petrol spit-back through the carbs has completely disappeared. It was indeed simply a matter of the wrong combination of cam profile/downdraft cylinder head/valve overlap.
I had a bad crack in the block of my 2 Litre as well as 4 cracks (not uncommon) in the aluminium bukhead of the car.
They were all perfectly repaired (using a “cold stitching” method) by Surelock, tel. 01572 722051 mob. 07768 366070.
You don’t have to bring your engine to them, they can do the work at your place, in my case I didn’t even have to remove the engine and bulkhead. They travel anywhere to do the job and are also frequently at LMB – the highly praised Lagonda experts in Belgium.
I can highly recommend them – the work they did for me is perfect and was all done within a day.These spokes have the exact correct size and thickness and are made of modern spring steel – rather better than the original. As many of us know, the lower spoke is often broken because one usually touches it when climbing in the drivers seat. Many Lagondas drive around with one broken spoke – my car did for 9 years; it didn’t look good and was inconvenient but not really dangerous at all. Never failed the MOT. I have seen many Lagondas with a primitively repaired spoke (poor attempts at welding, ugly bushes and even tape).
A well-known steering wheel refurbisher in Britain is very good but takes many months to do it at an exhorbitant price.
These spokes will enable us to do the job ourselves (as I just did) quick and at a fraction of the costs.
I have three left at ?95 – which is what I paid myself; no profit.
I wonder why the Newsletter did not publish my ad – I was promised that it would be put in. The fact that Arnold Davey does no longer handle the advertising does not seem to be an improvement.You could ask Alun Jones (Wessex Workshop) to refurbish your oil pump. He is very good at that and might be able to persuade it to behave more sensibly!
SURELOCK can do an excellent repair. Ask for Nick. – I can highly recommend them. I do not have their number here but they advertise regularly in the “Automobile”.
A week ago an original 4.5 Litre owners manual (1934) was for sale – it fetched $125. Unbelievable.
All I can say is that I had exactly the same problem – oil pressure going from the end of the scale to a nice 30 psi, then going up again and eventually ending up at a nice 20 psi. I never found out why. My advice: don’t worry and leave it like that
I’m afraid I’ll have to insist that for me no clutch-stop is best. And I have really tried. But, as it is, I love my car without it and I have no trouble whatsoever changing gears . You’re all welcome to drive my car (when it’s put back together, that is) and see for yourself! Interesting about the replacement of clutch springs with 3.5L types – what difference will it make? I did quite allright with the old ones (original 2L) but am very interested in any improvements.
Thank you for these useful tips – I will certainly take them to heart. Why are the clutch springs from the club too short? Florins? That’s two shillings if I’m not mistaken – I seldom get these as change in tesco’s 🙂 . There must be a more contemporary method?
As for the clutch-stop; even after trying 15.000 settings I did not notice any change in gearing down, and very little in gearing up. On my car at least it certainly does not “speed-up gear changing” at all and it wasn’t until I disconnected the clutch-stop alltoghether that I could really change gear pleasantly and without nasty noises. I agree with Arnold Davey on this one.All very well, but none of you have offered a real explanation for the petrol spit-back problem. And if I myself, after much thought, come up with the very plausible answer that it might be the combination of downdraft carburetter/valve overlap/camshaft profile, all I get from one of you is: “I would be surprised if, on its own, changing the cam profile would solve this problem”. I already knew that and it is not what I said.
The fact that we all agree on the merits of the downdraft head is not the issue. What we are discussing and concerns us now is applying this cylinder head the correct way, with the right camshafts, valve overlap etc. and getting the most out of it without creating a modern mongrel. I have tried to help those who have the same problems (H45 John). And to be honest, with all respect for Arnold, he doesn’t “set it out clearly” at all; actually he hardly mentions it in his new book. He only claims that none were produced at the time and that the picture is a mock-up. However, I myself know the location of an original 1930 Lagonda downdraft cylinder head.
Anyway, Colin – I’d love to have your answers to my qustions above.Colin, thank you for your reaction. You say that you might “change the camshafts back” – my question is which are you using now? I presume it’s flat lobed ones; did your engine ever (or still) suffer from the petrol spit-back problem?
As I wrote earlier, with the flat lobed shafts I got this problem of petrol spit-back, which of course resulted in much fuel consumption, and indeed a very inefficient engine.
If 100% of the petrol is properly burnt it will enhance the performance and efficiency. I think that changing to round-lobed camshafts will make a world of difference.Well, the engine is now being rebuilt and we’ll see if these new camshafts will solve the problem. Everyone who is working on it says it will. I too believe it is the logical answer. In the 1930’s, flat-lobed camshafts would not have been a problem with side draft carburetters and the standard valve overlap for the 2 Litre engines being only 9 degrees. However, I’ll keep the Forum posted. Meanwhile, here is a picture of the two types of camshafts – with flat and rounded lobes.
Personally, apart from the spit-back problem, I find much valve overlap and high engine revving on a long stroke Lagonda 2L when it is only used on the road quite unnecessary and it is not good for the engine. Also it makes the car less original and increases petrol consumption. I seldom rev my engine as high as 3500 and the car very nicely keeps up with modern traffic. At 3100 revs in forth gear (wonderful relaxed cruising) it does just over 70 MPH – quite fast enough for me! (And indeed the law).
If one races the car it’s a different matter and these modifications make sense. Besides, everybody has his own idea how to use or alter his car – I respect that.As I said above, if the lobes are very flat the valves stay open longer. Especially with much valve overlap, this causes petrol to be pushed back through the inlet valves and then the air inlets of the carburetter; no matter if it is sidedraft or downdraft, although it would be worse in the latter case as the distance between valves and carburetters is shorter.
The solution is to buy camshafts from the club which have rounded lobes (see picture in my posting below). I could also recommend to reduce the overlap to about 24 degrees or so – more overlap is only useful at very high revving; at lower speeds it actually works counterproductive.Unfortunately I have had no more reactions with advise how to cure the problem. However, I have discovered that the engine has rather unusual camshafts with very flat cams which means that the valves stay open longer. This could very well be the reason for the petrol “spit-back” problem. I am now replacing them with new camshafts supplied by the club – they are quite diffrent in shape with much more rounded lobes. I expect that this will take care of the problem.
As for downdraft carburetter inlet manifolds – they were done by Maniflow in Salisbury – tel. 01722 335378. They know exactly how to make them and often work with Burlen (carburetter manufacturers).Many thanks Brian and Stephen you for your advice. I contacted Wheelwrights but they didn’t have what I need, it takes ages for them to restore my old steering wheel and they are very expensive. I therefore looked around in my area and a local garage who have done some very good work on my Lagonda before are now making a new set of arms from the correct spring steel, using a laser cutter; it will be an exact copy of the original, all ready next week and very cheap. I still need the advance/retard lever system though, so if anybody out there has one lying around – please let me know! Meanwhile, as I can now get these spring steel spokes, I can help other people getting their steering wheel problems sorted and I’d be more than happy to do so – just let me know what you need.