'76 GLS (carb) Cold start: Running like poo

[datzed]

Ok guys, on cold start the car is useless.
- Wont hold idle (i.e. will stall) and will barely hold a steady engine speed at below 2000rpm with the throttle pressed slightly (i.e. will misfire).
- It will be running VERY rich (can smell petrol fumes)
- When you do drive, its not so bad, but when coasting, it will back fire loudly every now and then

Thing is, if I drive it for 10 mins, stop the car, and start it again in a few minutes, it'll pur perfectly.

I suspect either the cold idle valve, or temperature value is the issue. The temp valve supplies vacuum to the cold idle valve at coolant temps below 13deg and should close off vacuum at above 20deg. I'm hoping if I block the pipe supplying vacuum, I can fix the issue. But I have been unable to locate this pipe.

Firstly, can anyone help identify the cold idle, and temperature valve in the below pic?



Any idea where to get a replacement?
Has anyone had any similar issues?

[gldgti]

I only had expereince with a stock 1.6 for a little while before I swapped out the solex for a DGV, however assuming there are no vacuum leaks between the brake booster and the manifold, I would first try simply removing the pipe from the airbox to the carb and checking that the choke flap is closing correctly. The fact that it works after a warm shutdown/restart kind of suggests to me either a small vacuum leak or that the choke flap actuator is playing up.

I've never had an auto so a lot of the valves and hoses in your pic are foreign to me (the auto's have a more complex carb setup)

[datzed]

Thanks gldgti! Is the choke flap in the intake pipe after the air filter (or at the carburettor)?
I actually haven't checked for vacuum leaks yet. That might be a real PITA!

The weird thing is, the issue doesnt seam to resolve on immediate restart after getting warm. You have to let it sit for 5-10 mins, then start it before it is 100%.

[Jace]

i had the exact same symptoms with the standard carby.

i had to replace this


the carb could be filthy too, but i'm guessing it'll mostly be because of the massive vacuum leak because of cracks in the rubber.
only place i found to buy one was one of the MK1-friendly sites in Germany.

[datzed]

What is that?
And where is it in the engine?

[Jace]

under the carby, it's like a 90˚ adaptor and mine was perished as ****

[nick_mk1]

Just recently have and the same issue and yeh my carby base is destroyed.. It has a small hole in it ha :/ will see if it runs fine once it gets the new one in though!

[dr770]

Ok guys, on cold start the car is useless.
- Wont hold idle (i.e. will stall) and will barely hold a steady engine speed at below 2000rpm with the throttle pressed slightly (i.e. will misfire).
- It will be running VERY rich (can smell petrol fumes)
- When you do drive, its not so bad, but when coasting, it will back fire loudly every now and then

Thing is, if I drive it for 10 mins, stop the car, and start it again in a few minutes, it'll pur perfectly.

I suspect either the cold idle valve, or temperature value is the issue. The temp valve supplies vacuum to the cold idle valve at coolant temps below 13deg and should close off vacuum at above 20deg. I'm hoping if I block the pipe supplying vacuum, I can fix the issue. But I have been unable to locate this pipe.

Firstly, can anyone help identify the cold idle, and temperature valve in the below pic?



Any idea where to get a replacement?
Has anyone had any similar issues?

Before trying anything just check the pipe line from bottom of your carb to the upper part choke part,(not to the air box!) you will see it to the fire wall side. This vacumm line lets the choke plate open a little bit open once the engine is started and have actual vacumm. before the choke plate is fully closed to ensure high vacumm when starting the engine. İf this pipe is cracked your choke plate will be fully closed making it very diffucult to suck air for the engine at idle.

[dr770]

When you just stop the engine and wait 5 min the heat from the exhaust manifold just under your carb heats up your choke system releasing the spring letting the cold start mechanism off. So you can just start the engine with no problem. This problem is very common on solex pitch-34 and 35 series carbs. it was the same problem for me untill i have found a broken little pipe . but best for the car is to put a dual barrel webber , both on the performance and economy side.