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egret

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  1. Perhaps this is an area where unless it's horribly wrong it's basically fine?
  2. Just realised shimming is a compromised solution for when you skim the head and effectively increase the pushrod length to the point you run out of adjustment in the rockers.
  3. @Escadrille Ecosse of course! The fixed point is the top of the movement, when the valve is closed, so you want to shorten the pedistal to drop the pivot point. More lift = more open, as you can't get more closed than closed! Edit to show a quick sketch I put together to helped me understand a little better. It shows the push rod on left, valve on right. Blue lines being a notional standard geometry, and green being a higher lift geometry. I have somewhat picked numbers out of thin air to allow my brain to see it, but I show 1.5: 1 rocker arms and probably a rather extreme example of about 30% lift increase for the green- the blue is 15° max rocker rotation away from the horizontal with the green being 20°. It shows how rocker pedista, and pushrods need to become shorter to accommodate higher lift and how all the geometry moves away from optimal as the angles increase. Trying to deliver this higher lift without moving the rocker pivot point would be even worse (second image).
  4. I'm thinking out loud here, so please correct me if I'm wrong (and don't be upset if I'm attempting to teach you to suck eggs)! I belive the goal is to have the rocker arm movement be symmetrical around horizontal*. I.e. fully open and fully closed valve are equal angles away from horizontal. This way you keep the angles as small as possible and minimise any unwanted horizontal forces. I think the order would be: Measure pushrod (cam lobe) travel, and calculate/Measure valve stem movement based on rocker geometry. Calculate 1/2 way point in valve movement cycle. Shim the pedistals to make the rockers sit horizontal when the valve is at this half way point. Set pushrod lengths based on this rocker arm geometry. Check for binding Check some more for binding! *I'm not certain this is correct, it might be that with the valve closed the forces required to move the valve are lower than the forces to move it when fully open, so you might want to limit horizontal forces at fully open valve geometry. I assume the roller rockers will help on the valve stem end, but the pushrod geometry can be tricky too. I assume pushrods at too high an angle is a contributing factor to your issue.
  5. It works! Megajolt behaving and it revs a lot more freely now. Fueling is not great now though. I think the carb jets and needles need a clean as I couldn't get the thing pulling right. Enough glimses of performance to get me excited about it when it's properly sorted, and enough for me to be happy to book it into the rolling road and even signed up to the Stilton Cheese run on the 21st April, which seems like a fairly relaxed run out and relatively local.
  6. Given the drift on the few threads I've started with specific questions on my car I thought I should start a dedicated thread for what I'm doing on car. Summary so far is: Polybushes added almost everywhere. I've used a mix of red and blue to try and keep it from being too crashy. Lowering springs from D Faulkner springs. 2.5 Inch ID 9 Inch Free Length 320Lbs spring rate Lowering block at the back 1" Braded brake lines. Replica minilite alloys. Electric fan with thermostat. Re-built FD mk3 1300 engine, standard block. Bigger valve head with a 9.5:1 and a bit of valve fettling. 1500 manifold with twin HS4 SU Carburettors. Megajolt ignition. Tubular SS exhaust manifold. Stainless exhaust into carbon motorbike backbox (a nostalgic relic from my CBR600FX) Various usual brake overhauls, synthetic gearbox and diff oil, new trunion bushes, etc. etc. etc. I've been chipping away at a few projects to get it running properly. Megajolt is hopefully almost ready. I ended up waiting for a replacement chip in the hope that I could swap out the fried one, but after a couple of false starts, I've given up on that, so I'm putting in the new(er) megajolt I bought from ebay. Only problem is that this was set up for TPS, so I've swapped the MAP sensor off the old megajolt onto the new one, and hopefully will get that re-programmed with a reasonable ignition map, and tell it to use the MAP sensor rather than TPS. While this has been going on I've put together the air intake system, which I've been collecting parts for for years. Even so it's still a bit of a prototype as the plenum needs revisiting, and holding it in place with zip ties is not a permanent solution. I had a clamping failure when bonding the aluminium together. Somehow didn't manage to weigh it down evenly, so I think I will need to grind/file off the adhesive and re-apply. The gap is bodged at present, but tested watertight. I will say that despite my clamping issue, MMA (methyl methacrylate) adhesive is rather good. No need to prep aluminium, goes on like silicone and cures to handling strenght in 12mins with working strength in 30min. So work fast and make sure you have spare mixing nozzles, but it's really good stuff! So don't look too closely at the airbox, but the design principle is to maximise plenum volume in the availible space inside the wheelarch, then use large bore tube to connect to an oversized air intake filter in front of the rad. Other advantages are that I'm not fiddling with multiple components and gaskets everytime I want to take the airbox off to check the carbs, and I have some 3-d printed low profile velocity stack to connect inside the airbox to smooth out the transition too. This is another future addition as they need a bit of fettling. The goal now is to confirm the mejaolt works, then get it booked onto a rolling road to refine the ignition map and get the needle selection right. I'm happy to hear any comments, or warnings, on the design or execution of the inlet manifold system. N.B. the plywood deflector in front of the radiator is a placeholder, and I'm aware that some of the fabrication is a bit ropey, but it should be good enough to get me out driving the thing!
  7. That is looking particularly beautiful!
  8. I've that very same Victron unit in my van charging my leisure battery off a 100W panel. It seems like a good bit of kit, but I've not yet had the chance to properly test it. Hoping to get away over easter so will tax it a bit then.
  9. We all know the longest lasting solution to any problem is the temporary fix which works!
  10. I tend to use them for temperature comparison, rather than absolute temperatures. If you're looking at below about 100°C then using some black insulation tape to get a matt black finish is a good tip.
  11. I had a quick try with Fusion 360 and found it pretty good. Free for personal use, reasonably intuitive and similar to solidworks when I used that 18 odd years ago. It was recommended as a good start for hobby 3d printing design. I'm resisting getting into 3D printing as I already have too many hobies and not enough time, but theres a man on youtube 3D printing inlet manifods for ITBs and that's making the idea of a 3D printer very tempting. Luckily I don't have a suitable cross flow engine, so the temptation is avoided for the moment!
  12. To update this. I had an issue with a broken track on the board whihc, once fixed, solved my problem. I then flashed a new firmware to the megajolt and used th correspondingly aged megajolt monitoring software. It all talked and worked fantastically until I shorted the coil feed to something. I think this briefly shifted the relative voltages of the EDIS and Megajolt to rather different values and, because the pip signal into the megajoly processor is not protected in any way, damaged the chip. The good news is that trigger wheels still sell the processors, so I've one of those coming in the post and should hopefully be a relatively simple swap to get it working again. In the interim, I'll be paying more attention to my loom and making sure it's me-resistant, if not actually foolproof. I'll let you decide which is more onerous!
  13. Nope, it looks like the processor is toast Apparently the circuit design is not up to OEM standards and therefore not protected against acts of idiocy, such as my stupidity. The processor is out of production, and even if I could get it the firmware doesn't appear to be available. I don't suppose anyone has a kit sat unused at the back of a cupboard they are looking to sell?
  14. Today I got the spitfire running perfectly, I swapped the rev counter back to the megajolt output and it was all working as it should. What I didn't do was insulate or isolate the other feed I'd made (the coil signal), so I managed to short that out on something and the recently resurected megajolt once again stopped working. No obvious smoke, but it's not showing any signs of life in the car or talking to a computer. I've checked with a multi-meter, and have confirmed the basic 12v where there should be 12v and 5v where there should be 5v so no clues there. I've sent it back to Dad to look at with his 'scope. Hopefully it's a simple fix. I'm feeling particularly silly.
  15. The water pump housing on the mk3 engine I just rebuilt was one of the few parts that was not ok. The pump itself was fine, but the steel that separtes the high and low pressure sides of the pump had become paper thin and was missing in places. So in the case of that engine a brand new pump wouldn't have solved the problem at all! My understanding is that engines are closed systems so the amount of impurities in tapwater are fairly minimal. Disolved oxgyen and scale come out pretty quick, so as long as you're not continually topping up then you should be fine with the tap stuff. They reason scale is an issue in kettles, washing machines etc. is because you are continually replacing the water with new water that's full of calcium, so there's an endless source of scale. Closed systems drop the limited amount of calicum outout of the water as a small amount of scale then it's done.
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