Jon H

Yea i dont really care at this point. The OP had a flooding problem and high tank/fuel level is the most common cause of this issue so i offered advice accordingly. AS you post about tank height was wrong and would make the problem worse i had to correct it so our poor OP wasnt mislead....and here we are

2 stroke, 4 stroke, glow, diesel, inverted, upright, sidewinder, twin needle, air bleed... Its all the same and makes no difference at all. The fuel level should not be higher than the carburettor for any of them and the fact that you try to make this distinction between engines is clear example of you not knowing what it is you are talking about. No, i am disagreeing because you are wrong and your advice is also wrong. If you posted something that was factually correct, i would agree with it.

too true. with the greatest respect to the BMFA, they arent engine manufacturers and as with most people who write articles, run shops, make youtube videos they are enthusiasts working from their own experience without specific technical training or expertise in a given area. As i know myself, they probably also know that anyone who dares to question the old ways is immediately persona non grata. Consequently there tends to be an industry trend towards telling the people what they want to hear as most are impossible to educate. in any case, the nose up test is utterly pointless at best and downright dangerous at worst.

give it a rest pat, your whole reasoning is wrong and your 'i have done xyz for 30 years' argument isnt convincing. To see what i mean, just go for a drive if you like. Plenty of people who have been at it for 30 years are still hopeless at it. Doing the same thing wrong for 30 years dosent make it any less wrong. My tank level comments were totally relevant, as a tank setup like yours is likely why the engine was flooding. We really are approaching broken record status here but water (or fuel in this case) will flow down hill. If the tank is higher than the carb, it will flow down into it. I am fairly sure an 8 year old would understand this simple concept, but its apparently lost on you. As for the rest, for years you have disagreed with me on principal. If i told you the sky was blue you would argue about it. I have no idea why you do this, but its a trend which has persisted for the decade or so i have been on here. Fortunately for me, having left my former position i dont have to be as diplomatic these days.

If hand starting go the b&q and buy a broom handle. Chop off 12-14 inches, and save the rest for future use. As has already been stated, priming can be done with a finger over the exhaust (wont work on a laser!) and i use this method to hand start the saito 45 in my flair nieuport. I am helped out by the engine being inverted, so the fuel charge 'falls' into the cylinder, but it should work with a side mount as well. To be honest though, as i posted in the other thread my choice for a cowled scale model would always be a starter with a lipo. I use the big boy 6.5:1 geared job from JE with a 6s lipo on it. This laughs at my 60cc 4 stroke twins and gives me no trouble beyond the occasional switch welding problem already mentioned. As your 95v is not the biggest of engines the smaller geared starter from JE with a 3s lipo or even a bog stock 12v lead acid would do the job fine. If you are tired of a heavy lead acid, get a small nimh pack instead. I swapped my flight box over to a 3000ish mah nimh and its plenty for the fuel pump and a handful of starts. Its useless on a big motor , but i have used it on my laser 80 without issue.

I would use an external glow and a normal electric starter. If the spinner is aluminium, and i suspect it will be, the worst thing you will do is scuff up the paint a bit and you can always touch it up from time to time if needed. I have numerous ali spinners with some starter burn on the paint and i just hand brush new paint over the top. As the spinner gets more and more worn and chipped all over the paint repairs blend in for a nice weathered effect. With all that said, the OS should have start with ease if you can prime it. Old OS's used to have chokes and you might find that an ASP or SC 90 choke could be fitted. I wouldnt recommend adding any additional stuff onto the model in the interest of saving weight. I would rather have a horse shoe of lead just behind the front of the cowl than twice that weight in stuff but no lead.

saito 100's have tn carbs.

I know, i just enjoy pointing out the obvious mistake. I will never understand why people dismantle complex equipment with care free abandon, then get upset when they cant work out how to put it all back together as they forgot how it all went. It just baffles me completely. It takes but a moment to note/mark/photograph the relevant parts and build your own reassembly guide so why dont people do it? Anyway he's going to have a difficult time as the 180 had 2 or 3 different timings over the years and there is no chance at all i can explain how to work it out as, frankly, i cant remember the older timing myself as its been 10 years since i did one.

I mostly fly scale stuff, WWII fighters and the like. They never fly straight anyway and a 5 inch spinner looks ridiculous with side thrust on it so i just fly around the problem. The only model that has given me any trouble is my 1/4 stampe as it will only stall turn to the left with the engine at 0-0. I cant coax it into going right as i run out of rudder before the model stops moving. Still, its a small inconvenience and it stall turns nicely to the left so that works for me!

Note the position of the cams before you take it apart and then just put them back as they were.

I am in full agreement when it comes to c/g. Too many think its set in stone and the manufacturers recommendation is an immovable value. In reality, most models are massively nose heavy and come with excessive rates to compensate. Most of my models are massively 'tail heavy' vs the plans. When it comes to thrust lines i have gravitated towards just mounting everything dead straight as it saves a great deal of hassle and makes no difference to the handling of the model beyond a need for a little more rudder use. As i use the rudder all the time anyway its of no consequence to me.

i have seen this before and i am not convinced by the principal. its a solution looking for a problem and the reliability and performance of the system is dictated by the competence of the assembly. There are also so many points of potential failure/leak vs a normal system. He also talks about tuning 200 rpm rich of peak with a standard tank set up. that is a myth and consequently i am dubious about his qualifications. When at laser the tank height vs carb issue came up often and header tanks were suggested many times as a solution. A customer Steve Dunne worked out a pressure isolated gravity fed system that worked, but i couldnt recommend it as the system was quite complicated to get right. This caused many a debate, but unfortunately i had to make a recommendation that both an aircraft engineer, and the chap on the phone who was confused by his tank with only 2 pipes on it and couldnt work out where they went. I will always vote for the simplest system with the least failure points.

No, its not. I worked for an engine manufacturer, i know that i am right and you arent. You clearly do not have sufficient understanding to realise this, but its a fact. its a fact that is supported by other engine manufacturers too. The image paul posted is lifted from an OS manual, PAW say the same thing in the manuals for their diesels as well. The fuel level in the tank should not be higher than the spray bar and that is all there is to it. I know you simply disagree with everything i say on principal and will likely try to argue this until the thread is locked, but you are wrong and so is your advice.

I have rx's and servos that are certainly over 20 years old now and even my tx must be getting on for 17 or 18 years. I also have models that are a decade old full of their new at the time equipment. Some are still on their original glow plugs even. They are all working fine and giving me no cause for concern.

If the engine has no fuel in it you should get the thing cranking well before it actually fires. Thats why its important not to prime it

How are you powering your glow plug? The large number of start related prop throws could be due to an over powered glow ignitor causing pre ignition. I have seen this happen before when a clubmate cranked up his power panel to make his glow plug into a supernova. Also do you electric start? If so do you prime the engine first? If its yes and yes i would recommend you not prime the engine and just crank it with the starter. The in air failures are another issue...maybe, its possible that the nut is loosening during start and then gives up once in the air.

way back in history (the 1980's) saito engines were like little sewing machines and would tick away all day long without any fuss. I have a number of these engines (45's) and they are quiet, economical, smooth running, etc but not massively powerful. Then at some point in the 90's saito went 'ah ha, power....we need more power, and less weight, and ideally....more power...perhaps with less weight?'. I suspect this was influenced by the US market as i was once told saito sell 15 engines in the US for every 1 engine they sell in the whole of europe. No idea if its true, but its what i was told. The upshot of all this is they increased compression ratio, made valves and carbs bigger, used more aggressive timing etc and this had a profound impact on the running characteristics of the engines. They became much more on a knife edge, prone to prop throwing, guzzling fuel, increased vibration etc and generally less pleasant to operate. They also ditched bronze bushed rods to save weight (i guess?) which has bitten them in a bum since with failures, and upped their nitro recommendation which increased running costs considerably. The increase in nitro was required to prevent knocking/prop throwing as ignition timing of a glow engine is a function of the catalytic effect of the plug but also the plug temperature. A hotter plug will ignite the fuel earlier so advances the ignition timing. This is great as the plug will get hotter as the engine runs at higher rpm and the timing is nicely matched. However, if you crank up the compression ratio you increase the fuel charge temperature just through this added compression and can cause premature ignition. This can cause knocking before you have managed to tune the engine for peak power. If you run higher nitro you run a richer mixture (number of needle turns) due to the released oxygen from the nitro. This means you have a greater mass of fuel within the engine which soaks up the heat and reduces the charge temperature. Water methanol injection on full size engines works on a similar principal. You can overshoot with nitro though as the increase in fuel volume in the cylinder can also increase compression to the point where it knocks again as the fuel is incompressible. But if you dont want to shovel expensive high nitro fuel down the gullet of your saito engine you can run the normal 5/15 mix i always recommend. I havent had any issues with saito engines spitting the dummy but if they do then a shim under the liner is a good option. You could also use 2 plug washers (careful when you tighten it), you could sleeve the carb barrel down a little in size too. The really sad part about all this is their efforts did not yield significant gains in performance in most cases and they just made the engines less pleasant to operate. The saito 82 on 10% nitro is more or less a match for a laser 80 on 5% but wont swing as large a prop. The laser is heavier/physically larger in length, but the performance is very similar. The OS82 alpha is also on par with both and never fusses about 5% nitro. On your 82 specifically GG, how often do you shed a prop? Is it in the air/on ground, whats the power setting when it pops, what fuel, plug, prop, are you using a spinner...There is a long list of contributory factors and it might not be entirely the engines fault.

Its easy for the inlet on a 4 stroke to fill with fuel if the carb is even slightly dripping. Having the tank as the right height prevents this. Once the engine is no longer flooded and is running make sure the slow run needle is also set correctly as a rich slow run needle can allow fuel into the carb under the pressure of the fuel pump when filling the tank. it takes very little fuel to cause a problem. I have a similar issue with my sea fury due to the twin tank configuration of my laser v twin. The system is set up so that when full one tank will overflow into the other before overflowing out of the model once both are full. The fuel pump pressure on the full tank is enough to force fuel into the carb even with a good setting on the slow run needle. It wont flood the laser due to the carb configuration, but it makes a mess so i turn the model on, enable the throttle kill switch and then fuel the model. WIth the carb barrel fully closed the slow run needle cuts off the fuel flow completely preventing the fuel getting through. This is a very specific issue, but the principals behind the problem are what matters and you may need to look into something like this as well as moving the tank if the tank move/tuning is not completely successful as a cure. Cubans point about hydraulic locking is valid for 2 or 4 stroke engines. Broken conrods, even sheared crank pins are not unknown. In the case of a 4 stroke turning the engine backwards can help push fuel out of the carb but it makes an awful mess. Prevention is a better plan.

This tank is too high by about an inch and should be mounted lower so the top of the tank aligns with the carb. With a tail dragger you might get away with this setup from the point of view of flooding, but its not ideal and will result in tuning compromises to keep it running in the air. Improper tank placement like this is responsible for about 90% of engine issues if you look at root cause. The tail dragger vs trike discussion is not important when it comes to tank placement as the engine will always pull the fuel through with the tail on the ground and you need the tank set for perfect operation on flight as that is where the engine does its work.

Tank too high. As pauls picture shows and i have always advised, the top of the tank needs to be inline with the centre of the carb and not the middle of the tank. I do no know where the middle tank alignment idea came from as its incorrect and always has been. Top - centre has always been the correct alignment.

A 90 4 stroke will be plenty. My 63 inch hurricane is 9.5lbs and like a missile if I run it's laser 80 flat out. A 90fs with 14x7 prop would be my vote for power plant. Just make.sure the engine to tank alignment is good. Brian often arranged things where they would fit rather than where they needed to go and Th is can cause issues. I would expect a side mounted engine to be the best way to go

The full size P38 features an external mass balance. Perhaps there is a call to make it functional on the model.

More power will require more rudder authority to counter it so its critical speed may have been higher than a model with less power. All that said, most twin pilots never practice engine out procedures so its usually blind panic and confusion that ultimately causes the crash. not an overpowering fan either, but if larger engines are fitted then more blades might be the answer. Ground clearance is unlikely to be a problem with a P38 though unless its to the fuselage.

Assuming I have the same model I don't see a need for massive power. At 114 inch and around 40 lbs it's in the ballpark of 4 inches and 5lbs bigger than a 1/4 spitfire, and those have flown fine on z62 engines for yonks. Jan hermkins in the Netherlands has a p61 and a26 of 120 and 140 inches, with weights of 40 and 47 lbs. Both models fly fine on laser 240vs, which are broadly compatible to a z38. I really can't see a need for engines over 40cc, especially given how sleek a p38 is

How far back is the tank? And what is it's alignment to the carb? Also have you had it out and replaced it/It's plumbing? As the issue seems to be very much with the tan continually throwing engines at it is unlikely to solve the problem. I would expect a side mounted 4 stroke to give no issues at all so i would go for the root cause of the issue and sort the tank out.