hymodyne Posted April 3, 2012 Share Posted April 3, 2012 greetings, I'm still having issues tuning SU HS6 carbs I have on my '72 MKIII GT6.I have the SU carb tuning guide and I've checked and re tightened the nuts that hold the carbs to the manifold to address potential air leaks that would raise the idle speed. TSI imports mild street cam (S2), valves set hot at .015 (in)stock distributor, stock exhaust manifold, points gap set per manual.Carbs will allow engine to run without choke when adjusted out two and one half full turns on carb needle jet adjustment nuts, but will not idle below 2000rpm. It sounds like a dragster when its running (not the sound I want) , very steady but rough running. I am considering setting the ignition timing to between 6 and 10 btdcany suggestion to help me get the car to idle around 1000 would be appreciated.James Link to comment Share on other sites More sharing options...
piman Posted April 3, 2012 Share Posted April 3, 2012 Hello James, there are two idle screws per carburettor, one on the throttle and one on the choke lever. Make sure the choke screws are not touching the cam when the choke is fully home. Slacken one of the couplings that connect the two carburettors and see what that does to the idle. If it is still high, unscrew both idle screws so they are not touching the carburettor body.If the idle is still high, it may be that the throttle butterflies have been replaced and not set correctly in the spindles. They need to be moved around to get the minimum gap between the body and the disc before the screws are tightened.It sounds also if your mixture is rich, the datum setting is two full turns, not two and one half turns.Alec Link to comment Share on other sites More sharing options...
rotoflex Posted April 3, 2012 Share Posted April 3, 2012 I've got a 'medium fun cam' in my car, & I've given up on getting it to idle acceptably below 1000 rpm.Edit:Isn't the TSI cam a reproduction of the Triumph S2 "road" cam, & wasn't the S2 cam developed by Kas Kastner?You could go ask Mr. Kastner, who probably has the most experience & insights into setting them up.http://kaskastnersforum.yuku.com/forums/64/General-DiscussionHow cool is that, access to the guy who developed your original performance & SCCA competition parts for Triumph. Interrogate the man; it's too late to get Harry Webster & Harry Weslake on the phone for all the questions we'd like to ask them. Link to comment Share on other sites More sharing options...
hymodyne Posted April 3, 2012 Author Share Posted April 3, 2012 Brilliant! Thanks for the suggestion.James Link to comment Share on other sites More sharing options...
hymodyne Posted April 4, 2012 Author Share Posted April 4, 2012 When my crankshaft pulley is moving into the range where the before and after tdc markings come near the pointer on the block, my rotor is pointing at #6 piston, not #1. am I 180 degrees out? Can I take off the crankshaft pulley and rotate it 180, or do I need to do that to the distributor drive gear? I have also heard that the camshaft being off one tooth can contribute to rough runnning and other issues.james Link to comment Share on other sites More sharing options...
piman Posted April 4, 2012 Share Posted April 4, 2012 Hello James, it doesn't matter at all. The high idle speed is a carburettor fault or possibly an air leak down stream of the throttle butterflies. It's quite easy to check the valve timing, with number one cylinder at TDC firing, the number 11 and 12 valves should both have the same amount of lift.Alec Link to comment Share on other sites More sharing options...
don cook1 Posted April 4, 2012 Share Posted April 4, 2012 What is your timing set at at the moment as you say you are considering changing it to 6-10 btdc?? It's about that anyway isn't it? Check your ignition first (gets it out of the way). If not sure what to set it at then try running the car in 4th up an incline until it pinks and then back off (retard) distributor a bit. Are your carbs balanced, throttle spindles need freeing off for this i.e. set each carb individually. Link to comment Share on other sites More sharing options...
hymodyne Posted April 7, 2012 Author Share Posted April 7, 2012 I sprayed carb cleaner in different areas on the carbs and the throttle shafts increased idle speed when sprayed. Going to replace and move on the the next crisis :-/ Topped off the diff with Lucas 80-90 and bled three of four brakes.hoping to top off the T-9 gearbox for the first time and maype back her down the driveway.Happy Easter to all,James Link to comment Share on other sites More sharing options...
piman Posted April 7, 2012 Share Posted April 7, 2012 Hello James, "Going to replace" What are you going to replace? Alec Link to comment Share on other sites More sharing options...
hymodyne Posted April 7, 2012 Author Share Posted April 7, 2012 I considered replacing the shafts themselves, but have been given a suggestion of bushings for the shafts I have. where can someone buy bushings?james Link to comment Share on other sites More sharing options...
piman Posted April 7, 2012 Share Posted April 7, 2012 Helo James, for any parts for S.U.s, Burlen Services is the company.However, I don't think that is the cause of your very high idle. Either the throttle butterflies are not properly shut or you have an air leak downstream of the butterflies.Alec Link to comment Share on other sites More sharing options...
hymodyne Posted April 8, 2012 Author Share Posted April 8, 2012 Update:Carbs off, both butterflies clear the intake manifold and snap shut. when I hold them to the light I can see light around the perimeter of the disc, even when it is closed tightly. I feel some wiggle in the throttle shafts. I'd love to do this job myself if possible, even if only to reduce the transit time in shipping to someone else. I heard moss motors sells bushings...James Link to comment Share on other sites More sharing options...
rotoflex Posted April 8, 2012 Share Posted April 8, 2012 Hymodyne, where are you? Link to comment Share on other sites More sharing options...
hymodyne Posted April 8, 2012 Author Share Posted April 8, 2012 Salisbury Maryland, USA Link to comment Share on other sites More sharing options...
nang Posted April 8, 2012 Share Posted April 8, 2012 You could try loosening the screws that hold the butterflies and see if you can centre them, the holes have some clearance. you'll see by holding them up tp the light if you have improved them.Bushes on their own won't do much good, It'll be necessary to ream or drill the spindle holes, which is a precision job.Tony. Link to comment Share on other sites More sharing options...
rotoflex Posted April 8, 2012 Share Posted April 8, 2012 2572 wrote:Salisbury Maryland, USACall Joe Curto for advice & parts:http://www.joecurto.com Link to comment Share on other sites More sharing options...
piman Posted April 8, 2012 Share Posted April 8, 2012 Hello Hymodyne, also have a look at the discs themselves, the edges are slightly angled (I.e., they are not square to the face) and so should fit flat to the choke bore. If someone has replaced them some time in the past, it's possible that they are fitted back to front. It will be obvious if they are right or not.Fitting new bushes is not going to cure your very high idle, and personally, I don't consider some play in the throttle shafts as being that important. It mainly affects the idle mixture but when you drive the car they make little difference to the running.Alec Link to comment Share on other sites More sharing options...
hymodyne Posted April 8, 2012 Author Share Posted April 8, 2012 a picture of one of two worn throttle shafts:looking to new ones and new bushings.James Link to comment Share on other sites More sharing options...
junkuser Posted April 9, 2012 Share Posted April 9, 2012 Try the spindles first as they wear rather than the the throttle body metal they run in.The soft metal of the body tends to hold any grit, as it beds into it and this is what wears the harder metal of the spindle. Link to comment Share on other sites More sharing options...
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