turboplanner Posted May 7, 2012 Share Posted May 7, 2012 OK, I got a conflicting jet size online and didn't want to publish it in case it just confused the issue. That colour is what I would expect from the correct main jet. Link to comment Share on other sites More sharing options...
pudestcon Posted May 7, 2012 Author Share Posted May 7, 2012 OK, I got a conflicting jet size online and didn't want to publish it in case it just confused the issue.That colour is what I would expect from the correct main jet. According to Gary Flood and all other references I can find, the standard main jet size is 165, and that's what is in both my carbies. If you apply the conversion for my environmental conditions (airfield at 1330'amsl and 30*c) I need a 155. But that would lean it off a bit, so I'm staying with the 165 jets. Pud Link to comment Share on other sites More sharing options...
pudestcon Posted May 7, 2012 Author Share Posted May 7, 2012 Some photos of a fly around after solving the overheating issue. Check that temp gauge!! Pud Link to comment Share on other sites More sharing options...
turboplanner Posted May 7, 2012 Share Posted May 7, 2012 Fifty five degrees at five past two? Link to comment Share on other sites More sharing options...
pudestcon Posted May 7, 2012 Author Share Posted May 7, 2012 Fifty five degrees at five past two? That would be a bit cool eh? Well 55 kts at 2400' at least!! But just in case you missed it turbz; water temp gauge reads 65*, egts read 1150*, time is 1308, and tacho reads 5200. Pud Link to comment Share on other sites More sharing options...
pudestcon Posted May 7, 2012 Author Share Posted May 7, 2012 Pud, if the aircraft is performing close to what the others are (forget the 6800 rpm limit - I have never acheived it) accept it and enjoy flying. I have 700 hrs on an old grey head second hand engine, and then 100 hrs on a new blue head engine. I blew a hole in one of the pistons of the old grey head trying to get the "text book" figures. If the jets are as recommended by floods, and the carby setup is as recommended, the egt's close but a little low, accept it and enjoy flying the aircraft. I( just put 26hrs on mine over 5 days and the motor never missed a beat and performed well.I tried all sorts of changes and wound up back at the motor setup as per floods and the propeller pitch as per the recommendations of the propeller manufacturer/distributor site. (I run a 68inch 3 blade brolga with 16 degree pitch blocks through a c box 3.1 ratio.) If its close, fly it. Just my 0.2c worth. Yep, that's what I'm gonna do!!! Pud Link to comment Share on other sites More sharing options...
SAJ Posted May 7, 2012 Share Posted May 7, 2012 I like your dash Pud it looks better then mine. SAJ Link to comment Share on other sites More sharing options...
Methusala Posted May 7, 2012 Share Posted May 7, 2012 G'day Pud, before this story is put to bed there are a couple of things that occur to me. One is that we have remarkably parallel experiences. We both replaced grey heads with blue heads, not because the greys were dead but just "tired". Secondly, I didn't have coolant temp problems but I had previously "upsized" my radiators. When we mounted the existing propeller we found that the max revs had fallen to 6,200 from 6,500 with the grey head engine. Also the blue head was equipped with a rotational damper which the grey head wasn't. It seems that perhaps the blue head may have been de-tuned to produce a little less power. Some of the earlier engines had suffered cases of crankshaft failure. I wonder whether this may reveal the truth of the matter? Occum's razor has something to do with the most obvious answer often being the most correct. (By the way, the rotary valve is capable of being installed either side out - I don't believe that I have installed it incorrectly but I will check.) Regards, Don 1 Link to comment Share on other sites More sharing options...
pudestcon Posted May 7, 2012 Author Share Posted May 7, 2012 I like your dash Pud it looks better then mine.SAJ Thanks SAJ, I agonised for days over the design of the dash, and posted about it on the forums here somewhere:smash pc: Pud Link to comment Share on other sites More sharing options...
pudestcon Posted May 7, 2012 Author Share Posted May 7, 2012 It seems that perhaps the blue head may have been de-tuned to produce a little less power. Interesting Don, I recall a post from one of those ol' geezers - could have been turbz or facthunter who did ask the question about specs being changed. I didn't give it much thought at the time but it could be a plausible answer. Pud Link to comment Share on other sites More sharing options...
Guest Maj Millard Posted May 7, 2012 Share Posted May 7, 2012 Pud, Temp is bottom of the range of 60-80C...all good ?...........only onre thing missing on your dash as I see it....Guards on your ign switched !....I've got some nice new black ones here PM me your postal and I'll send you a couple gratis if you like....The flat black would look good on the yellow....I've also got a spare 582 tach here if yours is a two-pole, that'll cost though !................................................................Maj..... Link to comment Share on other sites More sharing options...
pudestcon Posted May 7, 2012 Author Share Posted May 7, 2012 Pud, Temp is bottom of the range of 60-80C...all good ?...........only onre thing missing on your dash as I see it....Guards on your ign switched !....I've got some nice new black ones here PM me your postal and I'll send you a couple gratis if you like....The flat black would look good on the yellow....I've also got a spare 582 tach here if yours is a two-pole, that'll cost though !................................................................Maj..... That's very generous of you Maj, funny thing is, I was looking at the photo posted above and was thinking the same thing. Not the first time I've thought it either - just done nothing about it. I'll PM you my details. Don't believe I'll need a tacho any time soon but there was someone who posted in a forum on this site somewhere recently who was looking for one. Pud Link to comment Share on other sites More sharing options...
Guest GraemeM Posted May 7, 2012 Share Posted May 7, 2012 Does anyone use the Hobbs/Tacho digital style as a tacho? Graeme. Link to comment Share on other sites More sharing options...
turboplanner Posted May 7, 2012 Share Posted May 7, 2012 Not as good as a dial for peripheral reference setting the throttle while doing other things Graeme Link to comment Share on other sites More sharing options...
David Isaac Posted May 8, 2012 Share Posted May 8, 2012 ...................... from one of those ol' geezers - could have been turbz or facthunter ........ You make me laugh Ian. Link to comment Share on other sites More sharing options...
turboplanner Posted May 8, 2012 Share Posted May 8, 2012 And that coming from one of the gang who is even mentioned in the Bible..... 1 Link to comment Share on other sites More sharing options...
David Isaac Posted May 8, 2012 Share Posted May 8, 2012 And that coming from one of the gang who is even mentioned in the Bible..... Ahhh yes ... But there is one of us that exceeds all of us in age our beloved Donald Methusela of ACT fame ... Link to comment Share on other sites More sharing options...
turboplanner Posted May 8, 2012 Share Posted May 8, 2012 ...who has lapsed into a self imposed silence, for 40 hours, 40 days and possibly 40 months and 40 years? Link to comment Share on other sites More sharing options...
turboplanner Posted May 8, 2012 Share Posted May 8, 2012 I think you are on top of the overheating with the bigger radiators, but just a small thing. Sometimes we can change something - radiators - which actually masks an underlying fault - running lean. We assume we've fixed the problem but then one day we burn out or collapse a piston. We know the main jets are corrected from comparing with the manufacturer's specification numbers and seeing a nice tan on the plugs. But upstream from the carby a hose size or kink, joiner, tap, filter etc can be restricting the flow and in fact becoming the main jet. A quick test to rule this outg it to disconnect the fuel lines at the carby, allowing flow through all the lines, filters and fittings, turn the taps on and time how long it takes to put 600 Millilitres into a plastic measuring jug. For a 500 cc engine it should reach the mark in 30 seconds. If it passes that test you've got unrestricted flow right through the jets, so you can relax in that area. A simple rule of thumb for cooling is to measure the finned area (length x width) of the successful loan radiators. If you duplicate that area , either by similar tall radiators, or the third radiator Facthunter mentioned, you will get the same performance PROVIDED the tube spacing and size is the same and the fin spacing and size is the same. If not it's back to the drawing board Link to comment Share on other sites More sharing options...
Riley Posted May 8, 2012 Share Posted May 8, 2012 Further to Turb's above post, I seem to recall fm my revhead youth days that speedway freaks used a rule-of-thumb that 1 hp required a minimum of 1 cu inch of radiator volume. Anyone ever used and proved it or am I having a senior's brain fart? Link to comment Share on other sites More sharing options...
turboplanner Posted May 8, 2012 Share Posted May 8, 2012 Further to Turb's above post, I seem to recall fm my revhead youth days that speedway freaks used a rule-of-thumb that 1 hp required a minimum of 1 cu inch of radiator volume. Anyone ever used and proved it or am I having a senior's brain fart? There may have been rules like that, but I pour methanol through the engine at about twice the jet size of petrol and don't need other cooling devices because the liquid does the cooling in the chamber and squirts, hot, out the exhaust. Where a petrol engine would quickly choke with a richer mixture, methanol has a huge overlap where richer doesn't matter. In this case Pud's actually got a size that works, just a matter of if he can't get the taller radiators he might be able to fit a third one. Link to comment Share on other sites More sharing options...
pudestcon Posted May 9, 2012 Author Share Posted May 9, 2012 I visited a motorcycle wreckers today and parted with $75 to get this.... I'll fit it similar to how SAJ has configured his setup. I think it will work very well, although the extra cooling area it gives me is 264cm2, when I only require 166cm2. I'll play with that once I see how it affects the operating temperature. What do you think? Pud Link to comment Share on other sites More sharing options...
facthunter Posted May 10, 2012 Share Posted May 10, 2012 Should do the trick. I wouldn't worry about it being bigger than you need ( in theory). You would probably get a NEW one off on of those little chinese bikes for the same price. ( next time eh).. Nev Link to comment Share on other sites More sharing options...
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