I've had this issue since obtaining the E3. On starting from cold on auto choke the engine initially revs far too high, around 2000rpm just for a couple of seconds then drops down to around 1500. It's long enough to generate a slight top end rattle due to lack of oil. I've read the manual but perhaps it can be explained easier in layman's terms. How do i adjust the mechanism to prevent this ?.
Startup Engine Rev's Too High
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Philippe db
Well-Known Member
If you have the original Zenith's installed you'll need to adjust both idle screw in the choke housings accessible from the passenger site.
Best remove your air filter and have somebody assist you to push down the acceleration pedal so the adjustments screw will appear. Not easy to acces but doable with and angled screwdriver. One full turn to the left will bring down your revs with 300rpm.
Best remove your air filter and have somebody assist you to push down the acceleration pedal so the adjustments screw will appear. Not easy to acces but doable with and angled screwdriver. One full turn to the left will bring down your revs with 300rpm.
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First thing to do if Zenith, join the two carbs vacuum by running a hose from the base of one to the other. deQ posted this and it made a nice difference overall.
What kind of carbs? The cold start mechanism will likely need adjustment on one or both carbs.
Sorry i should have said it's the original Zenith carbs with automatic choke. I don't think the idle screws are the answer, once warmed up the idle speed is correct. The adjustment is within the choke mechanism which, having read the manual, seems very complicated to adjust so any tips would be most welcome.
Sorry but can you explain further. Do i need to remove the covers from the choke housings ?.
Philippe db
Well-Known Member
No you don't.
When flooring the accelerator pedal the adjustment screw will come out of the housing. These are not your normal Idle screws they just regulate the choke function.
When flooring the accelerator pedal the adjustment screw will come out of the housing. These are not your normal Idle screws they just regulate the choke function.
Philippe db
Well-Known Member
Ah i see. So i need a 90 degree screwdriver, is it slotted or Philips head ?.
While it can be done like this the proper way is to warm the engine, set the throttles in the cold start position by pressing down on the throttle bar and moving the choke linkages so they hold the throttle plates open. This is what happens when you press the pedal to the floor before starting a cold engine, the tension from the choke actuators makes the linkage catch on a little step when the engine is cold. Once they are in position then you can use the screwdriver to raise/lower the rpm of each carb, preferably with a synchronmeter so you can verify both carbs are equal. If not, the engine could shake from being out of balance while it warms up before the pedal is blipped and it goes down to the normal linkage setting.
Steve,
So this procedure will place the engine at the rev's experienced when performing a cold start, but with the engine fully warmed ?. I'm guessing that this is preferred as you are actually adjusting the rev's to a known value as opposed to turning the screws with the engine off and hoping that you get it right ?. I think I'd need to see some photo's explaining what to do to the choke linkages as you describe, just to be sure I'm doing it correctly.
Good point. I'll double check before making any adjustments.
Message me your email and I will send you the Zenith manual
Correct, it will set the car to what it will idle at once warmed up but before you blip it down to normal. I think the book says 1700 rpm but can check.
Resurrecting this again. I haven't yet tried to adjust the choke, as I have a query. The issue I have is the immediate startup engine speed, way up around 2500rpm and this is enough to cause a nasty rattle due to the oil pressure not building up quickly enough. Only lasts a second or so but enough to make me wince. If the ambient temperature isn't too low I can immediately blip the throttle and it settles down to around 1500rpm, that I am assuming is the fast idle speed that the above adjustments will alter, and not necessarily the instantaneous 2500rpm that I'm experiencing?. So, will the adjustments above reduce this initial over rev' or only the subsequent fast idle after blipping ?. Maybe something else in the mechanism is sticking ?. There are no other indications of lacking oil pressure. It's the last thing you want to do to a cold motor, rev the nuts off it before oil pressure is up.