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jonbill

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Everything posted by jonbill

  1. ah yes, I get it now, thanks.
  2. surely an idler sprocket isn't going to impose much speed variation on the chain - it'll be completely dominated by the driving and driven sprockets, so wouldn't the polygon effect mean the idler sprocket speed varies instead? the term and concept is brand new to me, so I could be completely wrong.
  3. thats a fair bit of work. did you have to lower the rear arm mounts too?
  4. Ah, we're talking about the twin idler, I thought you were hinting the longer chain would be different! I've has it for years on the previous couple of engines. I love it.
  5. There's a lonf thread on here about it somewhere. I think the main points is it controls the chain at high RPM and especially when the engine is decelerating - the standard setup lets it go baggy on the tight side, changing timing. Also its dead handy for taking up extra slack after you skim the head and also it doesn't try to fall out when you take the head off. I'm not sure about it sucking energy to make that noise. It really is just two idler gears with little resistance. Maybe something to do with the oil spray from it.
  6. what should I expect? I'm using the Kameari twin idler, so I'm not expecting trouble
  7. Thats a thought. I have an RT mount as a snubber, so would only need to add the GM bit. I understand it lowers the diff a bit by default.
  8. thanks, that makes sense. But, how would I shim the front of the diff to get it lower? surely a shim would raise it?
  9. I had to grind the inside of the bell housing some to get the clutch to clear. I'd read that about the XTD RB flywheel and clutch some time ago and forgot so that cost a few hours. Next problem: with the taller block, the exhaust fouls the bottom of the bellhousing. More grinder work.
  10. I've made my engine mounts and the engine sits in the engine bay under my strut brace. the engine is sitting about 15mm lower than standard. I think that means that the gearbox tail will be higher now, having pivoted about the gearbox mount, changing the driveshaft angles. Which I assume is undesirable, so I'm trying to work out how much to lower the gearbox to correct it. Do I want to lower it enough to position the gearbox output/driveshaft front joint at the standard level, or do I want to lower it a bit more, to keep the angle with the rear driveshaft joint as close to standard as possible? i.e. do I lower the gearbox to be on the dashed line, or on the dotted line? https://docs.google.com/drawings/d/1a1wM6wG2ZG1w3WTNqj22jJPKzhEA00ezUdC-XjMPnTs/edit?usp=sharing
  11. Engine is assembled. Next step, trial fit in the engine bay and figure out the engine mounts.
  12. jonbill

    Speeduino

    FWIW, I don't use a cam position sensor. I use paired injectors and wasted spark. The current standard boards can't so 6x6 sequential anyway. AIUI, sequential is over rated!
  13. Oh, and I've done some measuring up of the XTD RB26 flywheel and clutch in comparison to my std flywheel and ACT clutch in the current engine. The current clutch collar is 24mm tall, and the XTD setup is 5.5mm taller than the ACT setup, so I'll be going with an 18mm clutch collar, which I *think* is the standard collar for S13/S14 FS5W71C gearboxes.
  14. I took the old engine out at the weekend to take the head off and get the Kameari twin idler setup off and on the new engine. This week the head is being drilled for M12 bolts and the timing cover finished. I've also been measuring up and making lower engine mounts. It's more complicated than I imagined, since the mount faces on the cross member are at an angle and 15mm shorter mounts will lower the engine more than that I think - and the engine brackets end up hitting the mounts below their mid point, so I think I'll have to do something to correct that, maybe. Anyway, I hope to assemble the engine next weekend.
  15. I doubt they will make any difference to idle/cruise. I'm sure you'll get there.
  16. the only potential downside of smaller chokes is at the higher rpm. a mild 3.1 at 7000 may get all the air it needs from 36mm chokes and there'd but no downside. the upside would be no or less lean hole in the transition to main jets.
  17. Idle through high speed cruise will all be on the idle jets/progression holes. the problem is with the transition from progression holes to the main circuit. the bigger the choke, the lower the air speed and the later the main circuit starts. There's richer and leaner emulsion tubes, yes, but thats not the only way they can differ. On the Dellortos, a .9 emulsion tube is richer than .7, but starts the main jet later. something to do with a hole at the float level lifting the emulsion earlier than without. if you find an emulsion tube that starts earlier, and maybe it is richer, you can make it leaner again with smaller jets, but it'll still start earlier.
  18. This looks pretty good for explaining how emulsion tubes work, although might be talking about downdraft IDFs, so references to up and down etc might need some thinking about for DCOEs. http://www.performanceoriented.com/performance-tuning-2
  19. The progression holes are the jets until the mains kick in. your idle jet is already quite rich, so although a bigger idle might cover it, it would make you way too rich everywhere else. a different emulsion tube might start your mains earlier. I had Dellortos so not familiar with what the early starting ones are, but I expect google knows. Also I'd think you wouldn't loose much if you went to 36mm chokes, revving to 7k. My cam is 15mm lift and 308/9 duration and revs to > 8k and wanted that extra flow. it took me about 5 years to learn enough to get them to run great. I now have ITBs and EFI and it takes a couple of days to get the fuelling as good.
  20. I ran 39mm chokes on my L29 very happily. However, I did have to add a progression hole between the existing standard 2nd and 3rd holes. Big chokes can mean it goes lean between progression holes. What do you rev it to? TBH if you don't rev it, a smaller choke will fix the problem easier than finding where to put more progression holes and making them
  21. jonbill

    Speeduino

    I had to look up staking and potting 😊 I did glue the DSC in with hot melt glue - it did used to work lose. No problems in use, its been very reliable. It's not a daily, it only comes out when there's no salt on the roads.
  22. jonbill

    Speeduino

    That'll work well then. which board are you using?
  23. jonbill

    Speeduino

    What trigger pattern are you doing on that CAS?
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