Dual Weber DCNF Choke Issues

Keep it on topic, it will make it easier to find what you need.
Post Reply
drovak

Dual Weber DCNF Choke Issues

Post by drovak »

Hey guys,

I've been working on the '76 quite a bit lately, mostly with interior. Today I took out the pedal box (despite being a "young and agile" 19-year-old, it was QUITE a pain!) to assess the cracked firewall. It's pretty bad from the looks of it. Quite the weak spot apparently.

Anyways, last night, I wanted to start it up since I hadn't started in a couple of days. It took probably 15 to 20 seconds before it actually started, and it died right away. After trying for a second time and giving it a little gas, it started, but it was still acting grumpy, i.e. spitting and backfiring for a minute or so, etc. Finally, the car warmed up and sounded pretty good.

Today I started it, and it only took it a few seconds for it to start. Does this mean gas had settled back into the tank in the first scenario and it didn't have as much time to settle in the second? Bad one-way valve? The fuel pump is definitely working. I even added a relay so that it would get the full battery voltage directly from the battery terminals.

Either way, on a cold start, it still apparently has trouble. It still is backfiring a bit until it gets warm. I thought this may be a choke problem. After checking what was hooked up to the choke arms on the dual carbs, I found that not only was there not anything connected to them, the two arms were not even connected to each other.

What should I do? Would a solenoid be a good choice here? What have other people done with dual carbs? I would like this car to look as authentic as possible from the inside. Another question: how was the stock '76 choke on the single carb controlled?

Thanks!

Kyle
drovak

Re: Dual Weber DCNF Choke Issues

Post by drovak »

Any ideas? How would I make an automatic choke that opens after the engine is warm? Or would it be better to choke it manually?

Your help would be much appreciated! ;) Thanks!

Kyle
User avatar
manoa matt
Posts: 3442
Joined: Thu Oct 26, 2006 4:28 pm
Your car is a: 1978 Fiat 124 Spider 1800
Location: Honolulu, Hawaii

Re: Dual Weber DCNF Choke Issues

Post by manoa matt »

Kyle,

Unless a previous owner changed things around, a 1976 should come stock with an electrical fuel pump, check valve, and relay. The pump and check valve will be located in the trunk by the tank. The relay is in the engine bay on the driver's side fender. The pump is wired in to the oil pressure light switch so in the event of a crash, and the motor stops or looses pressure the fuel will be cut off to prevent a fire. The pump should run when cranking.

Check your local auto parts store for a fuel check valve, if not check, the internet, it shouldn't be to expensive or hard to find. Alternatively you can wire in the pump with an auxiliary power and switch to "prime" the fuel system prior to starting. You flip a switch, let the pump run for a few seconds, turn off the switch and start the car.

There are two types of starting devices for carburetors. The strangler or choke, and a fuel enrichment device. Most carbs employ a choke or flap to limit the air and richen the mixture until the car is at operating temperature. The operation of the choke/flap can be manual with a cable, or automatic with a tiny electric heater or water from the engine coolant to heat a bi-metal spring that opens/closes the flap/choke. The 1976 came stock with a 32 ADFA 2 barrel progressive carb with an automatic choke flap connected to the engine coolant.

Your 76 has been modified with dual carbs that employ a fuel enrichment device which is operated manually via a "choke cable." The fuel enrichment device is like a mini carb that adds a little bit more gas and air during the starting phase until it is turned off by the driver via the cable. There is no real easy way to convert the starting mechanism from manual to automatic operation, you simply have to remember to turn it off when the car reaches operating temp. However if you are in a more temperate climate you may be able to tune the carb so the enrichment is not needed.

To connect the starting devices you need a choke cable (available at most any auto parts store) If you look up around the steering column on the left side you may see the original choke cable, or the bracket where it once was. Mount your new choke cable here, pass it through the firewall and connect it to the carbs.

Matt
Post Reply