JimEB Posted September 19, 2014 Share Posted September 19, 2014 Hi all :)I suspect that I need to have a look at the throttle balancing on my late, twin balance pipe PI. It idles pretty smoothly, but is a bit lumpy when pulling away, clearing its throat as you go up the rev range. Ignition seems fine, although I might get around to fitting a new coil and condensor at some point, there are nice pulses on every injector line and I keep a close eye on spark plug and points gaps. I'll also check that the distributor is advancing properly.I've got the works manual, in which there's a fairly rudimentary guide to setting up the late throttles (start at the front one and work backwards), but I wonder if any of you would have any practical hints or tips, please. I've already got a proper air flow meter (an old Crypton Synchro Check) and also a beer mat ;DThanks ;) Quote Link to comment Share on other sites More sharing options...
thescrapman Posted September 19, 2014 Share Posted September 19, 2014 Jimare you also getting a nice spray pattern, in addition to the feeling the pulses??CheersColin Quote Link to comment Share on other sites More sharing options...
JimEB Posted September 19, 2014 Author Share Posted September 19, 2014 thescrapman wrote:Jimare you also getting a nice spray pattern, in addition to the feeling the pulses??CheersColinYep, but I'll double check :) Quote Link to comment Share on other sites More sharing options...
Jason Posted September 19, 2014 Share Posted September 19, 2014 The acid test is really simple, you should be able to stick your thumb over the air bleed and stall the car. If you can't stall it then you have an air leak - probably a poorly sealing (and therefore poorly synchronised) butterfly.This is all rather easier to diagnose than to fix :o Quote Link to comment Share on other sites More sharing options...
JimEB Posted September 19, 2014 Author Share Posted September 19, 2014 Jason wrote:The acid test is really simple, you should be able to stick your thumb over the air bleed and stall the car. If you can't stall it then you have an air leak - probably a poorly sealing (and therefore poorly synchronised) butterfly.This is all rather easier to diagnose than to fix :oYep, the thumb test is what led me to suspect butterfly issues - the engine didn't stall but the revs fell to around 400 and the thing just wanted to keep running!Lots of fun to come ;D Quote Link to comment Share on other sites More sharing options...
josh18 Posted September 20, 2014 Share Posted September 20, 2014 Hey, the spindles can also wear causing air leaks. Quote Link to comment Share on other sites More sharing options...
Richard B Posted September 20, 2014 Share Posted September 20, 2014 Do all the butterfly splindles open together? Quote Link to comment Share on other sites More sharing options...
Richard B Posted September 20, 2014 Share Posted September 20, 2014 Do all the butterfly splindles open together? Quote Link to comment Share on other sites More sharing options...
JimEB Posted September 21, 2014 Author Share Posted September 21, 2014 Richard_B wrote:Do all the butterfly splindles open together?Yep, they do, but I think I need to finely adjust the daisy chain effect... I'll try to clean everything in situ - I shan't be lifting the bodies off the head! Quote Link to comment Share on other sites More sharing options...
JimEB Posted September 24, 2014 Author Share Posted September 24, 2014 To clean or not to clean? That is the question. :)I'm talking about the throttle bodies, in particular where the butterflies sit against the inlet when closed. I've heard that cleaning out the things can lead to additional air leaks once 'sealing' muck is removed.Thoughts?Thanks ;) Quote Link to comment Share on other sites More sharing options...
Doug Thompson Posted September 24, 2014 Share Posted September 24, 2014 Whatever you do don't clean them , you need the minimal gunge there to aid sealing of the butterflies :) Quote Link to comment Share on other sites More sharing options...
Jason Posted September 25, 2014 Share Posted September 25, 2014 The rumours are right, don't clean them it will screw it all up! You want them nice and dirty inside. Once clean you'll find there are air leaks. Also, don't take the butterflies out, you'll never get them back right! The only time you could clean them is if you were going to fit new throttle spindles and then you'd need to be able to put bushes in and line bore plus hone to get a tight seal. Clean the outsides all you want but leave the insides alone! Quote Link to comment Share on other sites More sharing options...
thescrapman Posted September 26, 2014 Share Posted September 26, 2014 JimI ignored all the advise above, and took my butterflies out and cleaned the insides.The car had been standing for 20-odd years and they were rank!Took about 2 years for the idle to settle back to an acceptable level (wouldn't go below 1500 to start with)You can get the best seal on the butterflies by holding body up to a bright light and looking down them. any hint of light and you need to adjust again.CheersColin Quote Link to comment Share on other sites More sharing options...
JimEB Posted September 26, 2014 Author Share Posted September 26, 2014 Thanks all ;)I suspect I might have a sticky injector, so I need to read up on how to disassemble and clean them, replacing the Viton O rings too :-/ Quote Link to comment Share on other sites More sharing options...
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