mleadbeater Posted October 10, 2023 Author Report Share Posted October 10, 2023 Andy, to me thats the whole point, if the car’s performance becomes suspect , then a good tool to help determine the cause is the vacuum gauge, just as is the ammeter or voltmeter, oil pressure, etc. I will think hard and sharpen my calving knife before “butchering” my newly veneered dash. All part of the fun of the discussion Cheers Mike Quote Link to post Share on other sites
BlueTR3A-5EKT Posted October 10, 2023 Report Share Posted October 10, 2023 22 hours ago, mleadbeater said: cant see any override on the wiring diagram, (which is a non-ballast diagram) the pump is fed off the same supply , via the ignition switch, terminal 2, and fuse terminal 1 , as the dizzy. Im still trying to find a correct wiring diagram for my ‘73 car, does such a thing exist ? Anyway, car electrics are getting far too complex for me, they’ll be fitting automatic steering and brake application device’s to moderns…oh, they already do ! Rant over, cheers Mike Your 1973 car has what I would describe as CR (1973 on) instruments fitted but also separate wiper and washer switches, ( pre 1973) Is the change to later instruments or earlier twin switches something you have done? Or is the car Comm no CC78521 to CR1 and a conversion to RHD? In which case tge wiring loom has been converted rather than replaced. Following is wiring diag for the comm nos as stated above. Quote Link to post Share on other sites
mleadbeater Posted October 10, 2023 Author Report Share Posted October 10, 2023 (edited) Thanks, Peter only had this car a couple of months. Im not sure of the history and mods to this car over its 50 year or so. Still finding extra and unconnected wires from previous owners. Its a mid 73 UK car, half the instruments are black rimmed, speedo and tach are chrome. im making all chrome ones, and need to rewire the voltmeter as ammeter removed. Not difficult but Id like to see the correct wiring. Is there a diagram for later voltmeter cars? your diagram is equally illegible as both of mine, wire colours particularly . Is a workshop manual version any better? or is this the source of yours.? Cheers Mike Edited October 10, 2023 by mleadbeater Quote Link to post Share on other sites
RobH Posted October 10, 2023 Report Share Posted October 10, 2023 These are about the best around ( but not 100% correct I believe) http://www.advanceautowire.com/tr2506.pdf Quote Link to post Share on other sites
BlueTR3A-5EKT Posted October 10, 2023 Report Share Posted October 10, 2023 1 hour ago, mleadbeater said: Thanks, Peter only had this car a couple of months. Im not sure of the history and mods to this car over its 50 year or so. Still finding extra and unconnected wires from previous owners. Its a mid 73 UK car, half the instruments are black rimmed, speedo and tach are chrome. im making all chrome ones, and need to rewire the voltmeter as ammeter removed. Not difficult but Id like to see the correct wiring. Is there a diagram for later voltmeter cars? your diagram is equally illegible as both of mine, wire colours particularly . Is a workshop manual version any better? or is this the source of yours.? Cheers Mike That wiring diagram is a photo taken of the workshop manual page in Triumph publication part number AKM3646. It is a white soft covered book covering TR4-6. It is the book that was produced after the ‘brown bible’, which ceases information for cars built after 1972 Quote Link to post Share on other sites
BlueTR3A-5EKT Posted October 10, 2023 Report Share Posted October 10, 2023 1 hour ago, RobH said: These are about the best around ( but not 100% correct I believe) http://www.advanceautowire.com/tr2506.pdf Great if you have an US Spec. TR. with carbs and warning buzzers and error proofing lights. Sadly missing the quirks of the PI cars, like inertia switch and pump. Quote Link to post Share on other sites
Charlie D Posted October 10, 2023 Report Share Posted October 10, 2023 17 hours ago, Andy Moltu said: How useful is a vacuum guage? Unless you suspect a vacuum leak all it will do is reflect how much your right foot is down. A bit more useful than just that: https://www.autospeed.com/cms/a_111456/article.html Charlie Quote Link to post Share on other sites
RobH Posted October 10, 2023 Report Share Posted October 10, 2023 (edited) As I said - not 100%. Try this one then - Apologies to the author for not accrediting it - I can't remember who did it but the link was posted on here a couple of years ago: "www.flickr.com/photos/34757865@N00/15441465529/in/photostream/lightbox/" Edit- found it - posted by Matt Taylor. Edited October 10, 2023 by RobH Quote Link to post Share on other sites
harlequin Posted October 10, 2023 Report Share Posted October 10, 2023 31 minutes ago, Charlie D said: A bit more useful than just that: https://www.autospeed.com/cms/a_111456/article.html Charlie Thank you Charlie for posting the link. I hope I am not straying to far off subject but I have a question. A CP engine will only draw about 12" of vacuum when in good condition, is this due to the cam or is it the injection system that is the cause of the low reading? George Quote Link to post Share on other sites
Charlie D Posted October 10, 2023 Report Share Posted October 10, 2023 Hello George, Far too technical a question for me, I'm afraid. I only mentioned the link because I once found the Vac guage readings useful many years ago to sort out some problem or other. Charlie. Quote Link to post Share on other sites
mleadbeater Posted October 10, 2023 Author Report Share Posted October 10, 2023 Gents, brilliant info, the diagrams are very clear, and progress the evolution of the car’s controls and other features. The vacuum info also fascinating, and certainly should be in any toolkit, particularly where PI is involved. To permanently fit one or not? ….still to decide. Cheers Mike Quote Link to post Share on other sites
harlequin Posted October 10, 2023 Report Share Posted October 10, 2023 Charlie Thanks for your reply, I have been experimenting recently with a vacuum guage, setting the timing and would like to find out more. Hopefully someone will come along with an answer. George Quote Link to post Share on other sites
Mike C Posted October 10, 2023 Report Share Posted October 10, 2023 4 hours ago, harlequin said: Thank you Charlie for posting the link. I hope I am not straying to far off subject but I have a question. A CP engine will only draw about 12" of vacuum when in good condition, is this due to the cam or is it the injection system that is the cause of the low reading? George Mine's 10" Hg,head modified a bit and fitted with a TR5 cam. I've always thought it was a cam characteristic made possible with the PI system. My thoughts are the PI system will let the engine idle with less vacuum than carbs leading to more air/power at the lower end of the RPM range. But it may simply be that Lucas couldn't make a MU that would work over a wider vacuum range back in the day. Quote Link to post Share on other sites
harlequin Posted October 11, 2023 Report Share Posted October 11, 2023 9 hours ago, Mike C said: Mine's 10" Hg,head modified a bit and fitted with a TR5 cam. I've always thought it was a cam characteristic made possible with the PI system. My thoughts are the PI system will let the engine idle with less vacuum than carbs leading to more air/power at the lower end of the RPM range. But it may simply be that Lucas couldn't make a MU that would work over a wider vacuum range back in the day. Thats a good though Mike I get 11" Hg with a CP cam and Strombergs, it ticks over and runs fine but maybe a little down on power on big hills. Which is why I raised the question thinking maybe the cam timing is a fraction out. George Quote Link to post Share on other sites
poolboy Posted October 11, 2023 Report Share Posted October 11, 2023 Yes check the cam timing, but also the ignition timing seems retarded with only 11 in-Hg vacuum at the intake manifold...unless that reading was taken at 6000 ft above sea level. Quote Link to post Share on other sites
charlie74 Posted October 19, 2023 Report Share Posted October 19, 2023 Here are he pics I would have posted last week if I had been at home: The connection is the line on the left (secured to choke cable), the brake servo is the other. Hope this helps! c74 Quote Link to post Share on other sites
Mike C Posted October 19, 2023 Report Share Posted October 19, 2023 Thanks Charlie. Looks good. For me that is a useful addition to the car's instrumentation . I'll have a look at the installation details when I next visit the car's garage. I'll sort out a connection to my PI manifold- shouldn't be a problem Quote Link to post Share on other sites
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