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Triumph Repair/1977 triumph tr7


looking for vacum diagram for zentih stromberg carbs books are very vauge and need more info. car was brought to me all taken apart and trying to put back together and make run. thank you for your help.

Hi Dave,

I have found that over the years most of the British car manuals are very poor on supplying vacuum diagrams, probably because the factory did a poor job about supplying vacuum diagrams.

As for the later TR-7 I can tell you some of the connections. The EGR vacuum should be run from the port on the top carburetor flange to a fuel trap and on to the EGR. Look at the diaphragm on the distributor to see if it is a vacuum retard unit. (vacuum port on the distributor side of the diaphragm) That should use straight vacuum from the manifold. Look next to the charcoal canister for a small electric valve with a vacuum port as that too should be straight manifold vacuum. Also there should then be a hose from the carburetor float chamber vents to that valve on the canister. This is an anti run-on valve. (sometimes the hose just ran to the top of the canister.

By the time the TR-7 was a few years old much of the hoses were disabled or blocked off for usually the wrong reasons.

Some versions of the older TR-7s had a throttle switch in line on the vacuum hose to the EGR and even some had vacuum delay valves in the distributor vacuum system. Many had different distributors due to the often failed Opus / Lucas electronic ignition system. So it is not often that the car maintained the same vacuum system over the 30 to 40 years.

I have found some diagram sections of the vacuum system so if you have specific question on a section let me know and I will dig to see if I have one on that particular section.


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Howard M. Fitzcharles III


Triumph TR-4 up & Spitfire, and Engine theory


Dealership line mechanic on MG, Triumph, Jaguar for 15 years, Instructor in commercial mechanics school 2 yr. Product information manager for piston and valve manufacture, Instructor & hotline answer man for import car parts importer 15 yrs.

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Import Car magazine

ASE Master Auto with L-1 certification up to 2000

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