Spitfire Hard starting Spitfire

[roofman]

I guess it's more accurate to say , <span style="font-style: italic">hard to get idiling </span><span style="font-style: italic">smoothly at start up Spitfire</span>. Here is what I have:
1980 Spitfire 1500. It has the Weber 32/36 DGV carb upgrade with manual choke. Car has good plugs, new cap and rotor, new bosch spark plug wires, pertronix electronic ignition module,it has a header, but is otherwise stock.
When starting the car it turns over fine, but takes a while to start. When it does start, it idles rough and I need to feather the gas pedal to keep the car running or ot will stall. After about 3-5 minutes of this the idle will even out nicely and idles between 1000 and 1100 rpm. Once warmed up it is fine. If I stop feathering the gas to keep the rpm's up it will stall and sometimes act as if it wants to backfire . It is fine once warm, and if I try to start it again soon it if fine, but even overnight it does this again. Something else I noticed is that the fuel in the fuel filter drains back after a couple days.
Any suggestions from the Grand Puba's of LBC's?

 

[roofman]

here are some pix.

 

[roofman]

This picture should be brighter.

 

[TR4A_IRS]

It sounds like the choke is not doing it's job. Have you verified that anything is happening when you pull on the choke knob?

 

[kodanja]

timing?

 

[71MKIV]

Is that with the choke pulled all the way out?

On mine, which is an earlier engine, but same carb, I start it with the choke all the way out, crank until it fires, then about halfway back in. enough for the high idle cam to keep the rpm's about 1200 or so. Choke goes back in all the way once I'm underway.

The spit back through the carb is definitly a lean issue. What idle jets are you running?

Mine always did crank a bit before it decided to run.

My filter always drained back too, which is why I kept the pump with the little lever on it, so I could manually pump the fuel up into the carb before attempting to start it. I come out of the airplane field, so priming an engine before starting is second nature.

 

[roofman]

I pull the choke out to start then have to play with it along with feathering the gas. If I push it in part way as is normally done right after starting it is won't idle on it's own without giving it some gas.

 

[71MKIV]

Hrmph<scratching head>, is this something new, or is it from when you bought the car.

If it's always been that way, double check your high idle cam setting. It's possible it's not moving, or never been set, as from the pictures it looks fairly new.

If the problem is new.... beats me, vacuum leak?

 

[roofman]

Not new, but when I bought the car the choke cable knob was broken off. I replaced with a new cable. When the new knob is pulled out, the cable works freely and the lever on the side of the carb pulls back nice and free so I believe I have it correct. I will double check to make sure it is pulling the lever back all the way.
I will have to research the high level cam setting as I have no idea what that means.

 

[myspitfire]

Bad idles are caused by bad cam's...do you use ZDDP?

 

[71MKIV]

In the mechanism the choke cable pulls on, there is a connecting rod that goes down to a cam around the throttle shaft. Your throttle plate closed screw sits on this cam. I'm not calling it the idle screw because on the Weber, there is a mixture screw and optional jets that have a roll in your idle speed.

The cam is supposed to hold the throttle plate open just slightly to increase the rpm's with the choke anything less than wide open.

My carb is off, I will see if I can get pictures. I have had less than stellar results from past attempts at pictures.

 

[roofman]

I doubt it is the cam, it is only on the start up. Once warm it runs perfect.
I rechecked my choke cable install and when the knob is pulled all the way out the lever on the carb does in fact pull all the way back.

 

[71MKIV]

I hate vista, what crap.

Now, starting all over after it lost what I wrote the last time.

The choke lever pulls on a cam which pull on a little crooked lever which pulls on the throttle plate.

According to my manual, a .030 drill is supposed to fit in the space between the throttle plate and the wall of the carb. (without dropping the drill bit down the throat of the carb :eeek

I suspect that you do not have that. The rod is made more or less crooked, in effect making it longer or shorter, to adjust the high idle.

I can try to scan the breakout drawing in my manual, but that is what I was doing when vista lost everything for me.