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Everything posted by JohnC

  1. I found this reference to Classic Valvemaster Plus. Amazing stuff - it includes "...a friction modifier Octimise-Plus within its formula, providing instantaneous acceleration by up to 3%." . <sarcasm> 3%? Wow. Oil clearly doesn't cut it when it comes to reducing friction. Much cheaper than that Phoenix exhaust, as well.</sarcasm>. To be fair, there is a link to an explanation of how the friction modifier works, but it does beg the question of what baseline it's in comparison with. Most (all?) modern oils come with all sorts of fancy additive packages aimed at things like...friction
  2. I'm curious about that. I understood VM was intended to protect against the valve seat recession risk from removal of tetraethyl lead, not as an octane replacement. How much would you need to raise the RON by a couple of points? By way of reference, when we still had leaded petrol here, but only as 95RON, the local Shell technical department recommended I add 10% toluene to bring the RON up to ~98. I can't find any data on how much the 1ml/1l VM treatment raises the octane. Anyone know? John
  3. You could always revert to the original bulb for that application. They were never too bright!
  4. Hi Bob, If you still have them, please would you re-post the pics/diagrams for this post? I've fitted LED instrument lights and I'd like to reinstate the dimmer switch. Thanks, John
  5. Fair enough. Not querying his safety observations, only the implication that it was Andrew who made the video. I'm glad our 98RON is all ethanol-free here in Oz. John
  6. Hey Clarkey, Just saying, but that's a little strong, don't you think?
  7. Or replace with an LED-compatible unit from classiccarleds, with LED bulbs of course. Brighter and louder
  8. Yes. And if you want to boast, just do the run in a downhill stretch with a following wind
  9. Depends what it's made of. You might try a hairdryer. Sometimes it's the surface texture that changes. I do know that the waterproofing of Gore-Tex (and other ePTFE fabrics) can be restored by tumble-drying. May be the same for dust-proofing. John
  10. I've ended up with CdA of 0.72. As you say, best to keep a consistent number otherwise you won't know much change there has really been. Same with rolling road dynos - I got significantly different results from two, only a few weeks apart, with no tuning changes. With PerfExpert, it seems to me that finding a really flat and straight stretch is critical. Straight more so than flat, assuming you take averages. It's nice to be able to compare before & after changes though, even if the absolute number may be a bit off. John
  11. Where did you source the pump (or the reconditioning)? Thanks, John
  12. Gaffer tape. Pretty sure WD40 won't work, so Gaffer tape it must be
  13. Hi Dave, What Cd did you use? I've been using 0.47, which I got from a GT6 dyno simulation spreadsheet somebody on here (sorry!) shared with me years ago. I'm guessing the GT6 is a little slipperier than my TR6, and probably your 4A as well. <edit> Just found this post on another forum suggesting the TR6 is 0.44 and the TR250 (and so I expect TR4/4A/5) is 0.45. Any thoughts?</edit> John
  14. Hi Marco, I'm with Stuart on this one. Look to your throttle linkage. There needs to be play, but only in the right places! I had this problem (kangaroo petrol at v light throttle openings). The root cause was a *combination* of no play in the throttle linkage *and* a missing bush in the throttle pedal cross-shaft. So the pedal was bouncing around and transmitting every movement to the throttle. Smooth roads - smooth engine; bumpy roads - bumpy engine. I replaced the bush and slightly slackened off the linkage. Delight JC
  15. Seems to be missing the bracket that holds the the cold start enrichment cable.
  16. FWIW, I've only fitted poly bushes to the suspension (everywhere). Blue bushes don't feel bone-shaking to me, and they're a vast improvement over the perished rubber they replaced. For a GB mount though, you are probably looking to minimise vibration at higher frequencies than from the suspension. I'd have thought the softer the better assuming sufficient strength. I wonder if there are any NVH engineers on the forum? JC
  17. JohnC


    FWIW, I have what I believe to be an early TR5 MU, and it has a tapped hole in the top of the body to take a PRV (or a pipe to one). So the high pressure feed to the PI enters in the usual place, unregulated, and there's a PRV regulated outlet at the top. Presumably the outlet from that went back to the tank. JC
  18. JohnC

    Lumpy running

    Just a thought, but why not go back to the garage that did your recent service? It sounds like the car was running well before it, but not well after it. Often it's best to look at what was last done to the car to figure out what's wrong. Second thought: You say the lumpiness is rev-dependent. Is it possible it's actually throttle opening-dependent? If so, the butterfly balancing suggestions would be a good place to go. At idle, the air all comes via the idle screw, so butterfly imbalance immaterial (unless one more is open of course). At WOT, any butterfly imbalance has minimal effect on
  19. Don't you hate it when somebody brings facts to an interesting discussion? Thanks Marko. You're not only an amazing machinist, but you know "stuff" too
  20. Unless you're incorporating the Lambda sensor into a feedback loop, the distance from the manifold isn't a big deal. If it has its own heating, even less so. I originally had one fitted just before the silencer, and moved it to the downpipes when I had a new exhaust system fitted. The relationship between manifold vacuum and AFR didn't change, even when looking at narrow RPM bands. Not that I could see, anyway. Obviously, if you're using the sensor to drive an EFI it's different. But for tuning the Lucas PI, or carbs, fit it where convenient. In fact, probably best at a point where the mixture
  21. Is the fit between injector and throttle body/ bush a big issue? I'm really not sure, but I do wonder if the air leaking past is pretty insignificant...
  22. I can't tell you how much I laughed. Go Norm!
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