cowman Posted April 7, 2007 Share Posted April 7, 2007 In my recent purchase of my MK1 PI it also came a boot load of spares, including a spare head and diff, among others items.Unfortunatly, the vehicle comes with no known history as its from a deceased estate and no reciepts or log books.Both look to in "good" condition.My question is how do i identify if this head is for a PI or from a later carb model 2500?What are majour differences between the heads? As the car is currently on triple carbs, would i be better with a head from a carb model?And can i identify the diff (ratios) from the outside?Sorry for so many questions.Any help would be appreciated.Thanks, Glen. :) Link to comment Share on other sites More sharing options...
cowman Posted April 7, 2007 Author Share Posted April 7, 2007 Thanks BT, that seems simple enough. :BNow, does it matter what head for triple carbs and id for diff (if its possible)Cheers,Glen. Link to comment Share on other sites More sharing options...
thescrapman Posted April 7, 2007 Share Posted April 7, 2007 The diff ought to have MDxxxxx stamped on it if it is a Mk1 PI diff. 3.45:1 is the ratio I think.CheersColin Link to comment Share on other sites More sharing options...
Deleted User Posted April 10, 2007 Share Posted April 10, 2007 Red paint on the output shaft nuts indicates 3.45 ratio (all 2.5) +MD or MG prefix = 3.45Later carb head has less CR (less running on ) and slightly smaller exhaust valves less prone to burning Link to comment Share on other sites More sharing options...
cowman Posted April 10, 2007 Author Share Posted April 10, 2007 Thanks Andy.The head is for the PI, numbers match with the info from the NZ Triumph site.The diff also has MD stamped on it so we can safely say its 3.45 ratio.Funny you mention the "running on" as this is a current problem i have with the triple SU setup.I assumed i would take care of the problem once i had an expert tune the carbs.But i have also found what appears to be a solinoid? set up on the fuel line that is no longer connected.I still have boxes of spares to go through and may find the rest of this setup, but i now presume this was to help stop the run on. (A switch is mounted under the ignition)Do you have any ideas of how the run on may be fixed or improved?Thanks,Glen Link to comment Share on other sites More sharing options...
Deleted User Posted April 10, 2007 Share Posted April 10, 2007 Running on is a real issue with carbs... PI's don't do it nor does my 2500 now it has EFI... before with twin HS6's (and a 9.5:1 CR) it was AWFUL.A fuel solenoid cut off might help but those float chambers hold a lot of fuel :-/ Link to comment Share on other sites More sharing options...
Glenn Posted April 10, 2007 Share Posted April 10, 2007 The MG Metro engines had a similar problem - high CR and a cam driven fuel pump.These cars had a device fitted to prevent running on - I have one that I was planning to fit to my PI engine on SU carbs.This is small electrically controlled valve which taps into the brake servo vacuum pipe via a T-piece. It has a solenoid which is connected to an ignition switched 12v. I think the device works by allowing excess air to be drawn into the inlet manifold via the servo hose when the ignition is turned off, making the mixture very weak and causing the engine to "conk out".I think similar devices were fitted to other cars. Carb'd Escorts spring to mind but no idea which ones (mk2?) Link to comment Share on other sites More sharing options...
Nick Jones Posted April 10, 2007 Share Posted April 10, 2007 My Vitesse used to have a chronic running on problem when on Stroms.I got in the habit of switching off in 4th gear, keeping my foot on the brake an lifting the clutch as the revs died away. This would usually stop it running on.Interestingly if it did manage it anyway, it quite often used to 'run-on' backwards! (stick it in 4th and lift the clutch to stall it and it would go backwards?!) On SUs the problem was much less and I think one of the reasons was that I could get a better idle at lower speed, meaning that when switched off the engine came to rest quicker without filling the exhaust with burnable mixture to be sucked back out again and burnt.With FI it just stops and never runs on forward or back.I too have come across the anti-run-on valve. These take two forms that I know of.On fixed jet carbs (80s VW/Audi stuff for example) the carb had a solenoid valve which blocks the idle circuit in the carb when the ignition is switched off. Effective but unhelpful for SUs or Stroms.The other (and I cannot remember what the vehicle I saw it on was now but might have been a South African Ford) was as described above; a solenoid valve that opens the manifold to atmosphere when the ignition is switched off. Also effective and could be retrofitted to just about anything BUT if they fail or don't seal well, re-starting can be impossible.CheersNick Link to comment Share on other sites More sharing options...
Deleted User Posted April 10, 2007 Share Posted April 10, 2007 I have a valve fitted to the taxi to prevent running on....is dosnt! but it was thrown on needs to be mounted closer to the manifold or best striaght into the manifold it was a standard Rover part will post a pic Link to comment Share on other sites More sharing options...
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