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TR6 vacuum system TR6

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Rob DeScherer

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When I got my '74 TR6, the vacuum system running fromt he EGR valve to the carbs and distributor was missing. I have done nothing to replace it. Does anyone know if it is okay to run the car without it? Could this be the reason why I am having a very difficult time adjusting the carbs?
 
Removing EGR control system (and thus disabling the EGR) will definitely make car run rich at mid-range and above....shouldn't have any effect on mixture at idle. EGR kicks in at mid-range (~2000 RPM+)and is a like a "controlled vacuum leak"....and engine is tuned to work with it. There may be alternate Euro needles for the carbs that will lean out mid-range or you could try dropping the needles (in the carb pistons) a bit. Be sure carb diagphrams are good....car will run terrible if they're ripped or cracked(I'm assuming it has Zenith carbs).
 
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by aeronca65t:
Removing EGR control system (and thus disabling the EGR) will definitely make car run rich at mid-range and above....shouldn't have any effect on mixture at idle. EGR kicks in at mid-range (~2000 RPM+)and is a like a "controlled vacuum leak"....and engine is tuned to work with it. There may be alternate Euro needles for the carbs that will lean out mid-range or you could try dropping the needles (in the carb pistons) a bit. Be sure carb diagphrams are good....car will run terrible if they're ripped or cracked(I'm assuming it has Zenith carbs).<hr></blockquote>

I do have Z/S carbs, but they are actually running extremely lean, so much so that the car will not hold an idle at all, but will stall immediately if the choke is off. We have tried resetting the low idle, but have found it to be impossible because we can't keep the car running. We ahve not found any vacuum leaks. Any ideas about what we can try next, or should i just pull the carbs off and rebuild them?

[ 05-11-2002: Message edited by: Rob DeScherer ]</p>
 
If your EGR valve is stuck open all the time, the car will run very lean, especially at idle. Using the choke will mask this to some degree. Remove the EGR valve and clean it in kerosene (or similar) and make sure the valve is opening and closing fully (it is noramlly "closed" due to spring pressure). Sometimes these valves get burned and will not seal completely (and you'd need to replace the unit)....but usually, they just get gummed up with carbon. In a pinch, you could remove the EGR valve and plug the manifold port that it attaches to.


Another thought: If one of the floats is stuck, the car could be running off one carb (because the float chamber would be empty in the "stuck" carb)....and the car would run lean. Try tapping on the float chamber with a small wrench to see if you can "un-stick" the offending float.

Another idea: to find vacuum leaks, start the engine and get it "idling" as best as you can. Spray WD-40 around the manifold gasket, the carb gasket, etc. If there's a leak, the engine will slow down as it sucks in the WD-40 (the WD-40 won't hurt anything....but it doesn't really burn like gas, so the engine slows down)
 
If your EGR valve is stuck open all the time, the car will run very lean, especially at idle. Using the choke will mask this to some degree. Remove the EGR valve and clean it in kerosene (or similar) and make sure the valve is opening and closing fully (it is noramlly "closed" due to spring pressure). Sometimes these valves get burned and will not seal completely (and you'd need to replace the unit)....but usually, they just get gummed up with carbon. In a pinch, you could remove the EGR valve and plug the manifold port that it attaches to.


Another thought: If one of the floats is stuck, the car could be running off one carb (because the float chamber would be empty in the "stuck" carb)....and the car would run lean. Try tapping on the float chamber with a small wrench to see if you can "un-stick" the offending float.

Another idea: to find vacuum leaks, start the engine and get it "idling" as best as you can. Spray WD-40 around the manifold gasket, the carb gasket, etc. If there's a leak, the engine will slow down as it sucks in the WD-40 (the WD-40 won't hurt anything....but it doesn't really burn like gas, so the engine slows down)
 
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