Triumph Repair: TR7 ZS Carb, fsad, diaphragms

Question
QUESTION: Hello Howard
I have a friend who has recently aquired a couple of late model TR7's.
He is having high idle problems on his '80 dual ZS 175's with the FSAD?? choke system.  He converted it to a manual choke.  When he starts the car it idles way high aprox 2K and the choke cable has no effect.  I only had a couple minutes to look at the car but thought his fast idle screws may be over adjusted.  He seems to say he is having difficulty locating the fast idle adjustments.  I am familar with the twin SU setups on MG's and others.  I thought he should try to get the idle down this way before I have him go into the idle deceleration valves.
Can you help explain how to do the basic setup  or suggest a place to view pics/instructions?  He said when he got the car in the summer it was hard to start and warm up but seemed to run OK? after warming.
Thank You for any help you may be able to supply.
Mike

ANSWER: Hi Mike,
If the engine is idling too high it means too much air is entering the intake so he needs to first look at the new manual choke to see if the long cam of the lever is contacting the fast idle screw (If it is the early type of manual choke)and if that screw is adjusted too high. If the manual choke is one of those aftermarket kits that uses part of the old coolant operated choke then you need to check the operation of the choke to see if it is holding the fast idle screw (directly behind the choke assembly) open too far also. You can tell by just, fully operate the choke while you watch the linkage.
If that is not where the problem is then look at the decell valves. It is common for the diaphragms to get dried out and stiff or the valve gets trash in it and does not seal well. I don't know if the diaphragms are available any more but you can remove the whole unit and clean the valve area and adjust the threaded rod so as to apply pressure on the valve to keep it seated.
Howard

---------- FOLLOW-UP ----------

QUESTION: Howard
Thanks very much for your explaination.  For adjusting the fast idle screw on this setup, is it only ONE screw for both carbs?  Not sure which manual choke is on it but it still uses the FSAD assembly.
Regards
Mike

Answer
If he still has the choke unit on the carb, it is for sure the aftermarket manual choke and I think it uses the original fast idle which is just one screw and it is on the throttle linkage just behind the choke unit.
When you have an unusual high idle on start up you need to closely examine the linkage to see what is restricting the throttles from closing all the way and I would guess it is that one adjusting screw. You don't need the engine running to see that. You should see that the carb throttle stop screws are not even hitting their stops when the choke screw is holding it open.
It would pay him to purchase a repair manual for the TR-7 as there are many pitfalls that can trap even a good mechanic if you are not up on some of the odd things on this engine. Haynes has a manual and he can order it from any auto parts store that handles Haynes Manuals.
The TR-7 car was very advanced for the time. The car was designed to be an MG to replace the MGB and was designed to have the GM 215 CI V-8 engine. The body was one of the first wedge shaped cars on the market and the body was crash tested by Mercedes Benz and had one of the best crushable nose cars to come out in decades afterwards. That 4 cylinder engine is half of a V-8 Triumph Stag engine. BLM acquired the 215 V-8 from GM but had not finished it when the car body was ready and since Triumph needed a car too, BLM had them just cut four cylinders off of the V-8 Stag engine and call the car a Triumph TR-7. When the 215 engine was ready they did put it in the TR-7 and called it the TR-8 Triumph.
I was factory trained on the TR-7 and thought is was a cool looking car but didn't like the short wheel base and thought it would not handle well. I would have liked to see larger diameter wheels and and a longer wheel base as I liked to broad slide and I was afraid it would be difficult to handle when out of shape. Since then I have owned five of them and found that like the MGB, I could recover from a full lock slide every time. In 1980 I received a DOE grant to build an Alcohol still and convert a car to run on straight grain alcohol. I chose the TR-7 (A short story of that is on my web site
http://mg-tri-jag.net/alcohol_fuel.htm )
 
Howard