Scott flame licker build

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Bogstandard:
Continuing on, getting things sorted in the hope that I can get some power out of it.

A few revelations after I got things done, I will explain a little later.

The grub screw holding for the valve lift arms needed beefing up a bit and to get them gripping properly, flats were required on the cross shaft.

With the cam set to give maximum lift and a machinists jack holding the graphite block in the correct position, by using a transfer punch down the grub screw hole, the shaft was marked up where the flat needed to be.

By mounting the shaft in the milling vice with the pop mark at the very top, a flat was cut on either end.

Next came the grub screws themselves. I had been using stainless ones, but unfortunately they are always rather soft and you can soon round out the allen key hole if you give them a bit of white knuckle treatment.

So for this job I went back to my normal high tensile steel ones after I had ground the ends flat so that they will sit correctly on the flat on the shaft.

By the time I had finished twiddling about it was time to try to get some life out of the engine, so by jury rigging the burner in position I gave it a try.
By playing about with the timing for ten minutes, I knew that I had it spot on, plus I had to do some serious bending of the cam follower rod to get things something like.

A few minutes later, I had it turning over a couple of times by itself, and I can now tell you, it is another 'duck quack' sounding engine.

But no matter how much I tried, I couldn't get it to run continuously. Then I noticed something quite alarming, as the cam is, it does not allow the inlet port to be fully uncovered, so the graphite block is in fact stopping the flame reaching the port correctly, hence the lack of continous running.

I am now going back to the drawings and check out all the geometry of the cam and lifting arms. I built everything to plan, and all that has been double checked at least twice, so it isn't my making at fault, but the basic design which hasn't been modified to show what is required to actually get the movements required to have the engine running.

I can now see why, on the engine I showed earlier, they had actually made the block a lot narrower, and as I suspect, they had the same problems as those I am finding now. I don't fancy making a higher lift cam as that will raise a few clearance issues, so, because I have a load of graphite I can play with, I am going to see if reshaping the graphite block will improve things in the running department. That might also mean I will have to make a new cross shaft with the holes in a different position, but I can get around that for the time being by bending a few brass arms.

It's all part of the game

Bogs

lordedmond:
Looking good John

It makes me wonder if there is a "perfect set of plans out there for anything in the model world ( except your paddle duck ones ) I have spent good money on plans and they mostly contain errors , the older LBSC ones are the worst the dealers just keep duplicating the masters they have and do not update them but keep charging the same ever increasing price .

rant mode off

it is a disappointment to me that the poor sole that has limited skill/knowledge can be put off because of the faulty plans

Stuart

ps got the rampant gas burner under control now thanks

Stilldrillin:

--- Quote from: bogstandard on March 21, 2011, 05:23:10 PM ---
It's all part of the game
Bogs

--- End quote ---

"Final adjustment, and tuning", eh John? ::)

Good luck! :thumbup:

David D

NickG:
Great work there John, sounds like you're nearly there and this trouble shooting is obviously brilliant info for somebody contemplating building it themselves. :thumbup:

I must admit, I thought this one would run straight 'out of the box' though. I'm a bit disappointed that a design that's been made commercially available has not had adequate testing and the design hasn't been revised accordingly. Will you be going back to Bruce with your findings or just accept that it's just the way it is?

We now have quite an extensive knowledge of flame lickers and know that they are tempremental beasts. However, as Stuart said, the unsuspecting modeller could spend quite a bit of cash and put a lot of time and effort into machining one and not get a peep out of it. In which case it'd probably end up under the bench which can be quite upsetting. Many people wouldn't have a clue how to go about solving the issues either.

The valve / linkage geometry and cam is very similar to that of poppin and from the last picture it looks to be timed very similarly to mine, shuts about 45 deg before bottom dead centre? Apparently it isn't even that critical with this type and mine would go along with that as it ran in the first position I put it in.

Great photos and workmanship by the way.

Cheers

Nick

Bogstandard:
Before I give comments on whether this engine is suitable for a beginner or not, after I get it running, I will be contacting Polly models about what was needed to achieve a running state, and depending on their reply, I will give it thumbs up or not.

I have been trying for a few years now, in my own little way, to give feedback to suppliers. Some just totally ignore you, so to me, they are not worth dealing with, but others, like Minimag, took on almost everything that I found issue with when I built their magneto, and remedied the problems on both the plans and build notes. In that situation, the supplier gets a big thumbs up :thumbup:, purely because they have the customer in mind as well, rather than just the profit margins.

I don't know if you noticed the Chronos website, last year it had a major revamp, and I hope to think that it was helped along because of my complaints to not only Chronos, but to PayPal as well, about how bad their site was. Showing items in stock, taking payments for said items, then a week later giving you a PayPal refund because they didn't have stock of the item you had ordered.
They actually stopped me ordering from their site, until I had another quiet word in PayPal's ear, after which time, Chronos' service has improved no end.

The other two 'biggies' in our supply world in the UK, Arc Euro and RDG both took on board a few comments either about service or products that I mentioned to them, and both remedied the situation very quickly, so they get full marks from me.

So no matter who you are, sometimes it does pay to contact suppliers and let them know how you feel about their service or products. If you don't let them know, how are they to put things right? If they are any good, they will do something about your comments, if they don't, just let the word out who the 'nasties' really are.

John

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