Hi Guys,

I rebuilt the carb on my inline 6 with a Holley 1940 carb and now the motor is a bit harder to start when cold.

Before the rebuild, I would pump the gas pedal twice and the car would start.

Now to get the car started I have to pump the gas pedal 5 times and it will start and then die, I then pump it 5 more times and the car will start and run rough for a minute and then be fine. If I try and give it gas during that minute the car also wants to die.

Once the motor is warm the car starts fine.

Any thoughts on what might be making this harder to start. I replaced the accelerator pump when I rebuilt the carb and checked its operation which is shooting gas in the throat of the carb. I have played with the choke a bit and got it to start better than when I first tried to start it a while ago.

Is there anything I am missing or should I just keep messing with the choke?

Its a pain to diagnose because I have to keep waiting for the motor to completely cool down when I make an adjustment to see if it made a difference.

Any advice would be appreciated,

Thanks,
Jay

 

Sounds like the choke isn't engaging fully. When the engine is cold, press the pedal and go look at the carb. The choke plate should be covering the air horn. If it's not, open the throttle and adjust the choke until it does.

 

Thanks for the reply Starfury, you made me take a closer look at the choke and I think I solved it.

I checked to make sure the choke was fully engaging and it appeared it was when the motor was turned off. However when I cranked it over the vacuum pressure started to open up the choke a bit.

There is a spring in the automatic choke that keeps the choke closed and I think it just needed a little more pressure to keep it closed.

I ended up just turning the choke adjustment all the way rich which put more spring pressure on the choke plate to keep it closed and gave it 3 pumps of the pedal and it started right up, if I gave it gas it did not want to die either.

So I think I just have to play with that adjustment, the spec called for +1 Rich which is a little over half way on the adjustment dial but perhaps because it is so old the spring may be getting weak and needed to be set richer to compensate for wear.

I will double check again tomorrow to be sure after the motor has cooled down all night but I think I found the problem.

The choke is obviously very sensitive to any adjustments, I really should have checked the setting before I took the carb apart.