Hard starting

[why]

67 Etype, 82,000 mi. On startup it stumbles really bad even with starting ether, after much throttle jiggling can get all 6 to fire. After a drive it starts immediately, then next day same old routine. After about 30 secs of stumble, rear three "header" stubs warm to touch, front three COLD. Fearing valve guide leaking, take out plugs, no oil visible, clean plugs anyway, still stumble till magic process of throttle massaging gets it to go, float chambers about 3/4 full, about to do from beginning carb set-up, any other thoughts? Can not imagine ignition cause so have not checked for spark during stumble period--will do so. There is a blast of smoke from exhaust for about 5 secs once all cylinders firing. Jay, (OfflineJ@aol.com)

 

[Marvin Gruber]

Jay,

My 68 XKE does the very same thing. I have put up with it the last year but blamed it on the gas we have now adays. Put Electronic Ignition on and no change. Spits and spudders for 5-10 seconds, then engine catches up and runs good. My car is not driven as much either. I have a Jensen Healy and TR3 that do the same thing as well. Maybe I am missing something or thats the way I have them tuned.

Marvin

 

[John S Farrington]

By nature, SU and ZS side draft carburetors are very cold natured. The cold starts that you are describing are very typical. On cold starts, these carburetors must have full choke or the starts will be very problematic. Make sure that:
1. The choke cable is actually allowing full choke. (when the cable is pulled out all the way, the choke levers are at their maximum richness position)
2. The float in the bowl of each carburetor is set according to specification. (the needle valve fully closes only when the choke float is at the specified distance from the rim of the float chamber top and/or the main jet is at its full downward travel when the choke is full on).
While you are trying to cold start, pumping or playing with the throttle pedal/valve does not accomplish anything towards the cylinders firing, To the contrary it might hamper cold starts. The carburetors are side draft and have no throttle pumps for priming fuel. You are better off to keep your foot off of the gas until you have an ignition. Holding the throttle valve open during starting will allow a flooded engine to unflood. You should start by assuring that your carbs are balanced and in tune as well as the choke mechanism being fully functional. If your E type is typical you will have to hold the choke lever up until the engine fires and begins to warm up. Hope this helps the start problem. Jack

 

[jessebogan]

Check also that the dampers in the dashpots have the correct quantity of oil. Check for vacuum leaks too.

 

[DrEntropy]

Yes, certainly check all, but the description of the problem (and its retreat after warm-up) is the ~classic~ cold start with insufficient choke symptom. John covered the details.

 

[John S Farrington]

As a footnote to this interesting discussion, if your British sidedraft carburetors (SU of ZS) are properly assembled and balanced, if your ignition system is in good shape (I do recommend solid state conversion from points), and if your battery is healthy, your British car should be a very reliable and fast starter even in very cold weather. If ease of starting and performance is a higher proirity than authenticity for your British car then make these conversions.
1. Solid state, pointless ignition with appropriately matched coil.
2. A fuel pump that is rotary veined without actuation points and matched to the car.
3. A gear reduction starter that is now available for most British cars.
4. An alternator that has a built in voltage regulator.
5. You DO NOT have to convert to Weber caarburetors.

With these modifications you will have far less trouble with your every day driver you will have eliminated the major bugaboos of our cherished British sports cars.
Keep the faith.