Hard starting a cold engine

[Bombayduck]

Hello again. I have a new to me 1981. It looks like the former owner(s) removed alot of the smog and computer stuff. I think this car qualifies for a "Bubba" award. My problem is the engine is really hard to start after sitting overnight. The carb does squirt fuel into the forward 2 barrels when i pull the linkage. It seems I have to pump 3 or 4 times to start then it dies then a couple more tries and it catches for a few seconds. I don't push the gas pedal when cranking. Finally it starts and runs rough for a couple of minutes. When it's warm it starts right up with just a flick of the key. I think it's the choke system but don't know how to check it or even what to look for. There are no electrical connections to the carb. I did some research on the number on the carb and found that it is a Carter Quadrajet (same as Rochester it says). I have also recently put new plugs, plug wires, dist cap and rotor. I set the timing at 8 degrees BTDC at idle with the 4 wires disconnected, but I don't think that mattered as the computer is disconnected anyway. Here's a picture of both sides of the carb
Thanks in advance for your help!
Brad

 

[Antz81]

Whats the number on the carb? It may be of some use for someone.

I had a cold starting problem with mine because some 'bubba' removed the choke plate meaning i was running with the choke always wide open.
I'm no expert, but there appears to be a manual choke on your carb, but it doesn't seem to be connected to anything for adjusting. Without this you are essentially running with no choke.

With your timing unless the computer is connected or a vacuum advance has been added then your timing won't advance with the engine speed. This would need to be addressed.

 

[Bombayduck]

The number on the carb is 7047186 "mfd in USA for GMC"

The timing does advance up to 12 BTDC when I rev the engine so either there is something still coming from the computer or there is some weights spinning in the dist. I didn't see any when I replaced the cap and rotor.

So if I have a manual choke how would I go about making it operational? There is a vacuum line on the front side of the choke going to the front of the carb.

 

[Vettehead Mikey]

So if I have a manual choke how would I go about making it operational? There is a vacuum line on the front side of the choke going to the front of the carb.

It's a mechanical choke, not manual. The intake manifold has no provision for the linkage, so your best option is to convert to an electrically operated version.

These people

Rochester Quadrajet Tech Info - The Carburetor Doctor

sell the bits and pieces.

I'd want to sort out the distributor too. You won't get much HP if the maximum advance is only 12*.

 

[Bombayduck]

Thanks for the link. Lots of info there. What's the difference between a manual choke and a mechanical choke? Pardon my ignorance but I'm on a steep learning curve

I do plan to get the dist sorted out but working in the starting taking priority now.
Brad

 

[Vettehead Mikey]

A manual choke has a knob or lever that the driver would move 'manually'.

 

[6880 Mike]

FWIW: Your current carburetor is not original. 81s used the "electronic" Qjets because of the computer.

 

[Bombayduck]

I'm finding out a lot of things about this car are not "stock"

UPDATE: I bought a new Street Fire Dist. and installed it and set the timing and wow, what a difference that makes! The engine runs 100 percent better! Way more power and throttle response. It even starts a little better too. My idle timing (with the vacuum advance plugged) is set to 10 BTDC and revved up stops at 32 BTDC. and with the vacuum advance hooked up it starts at 10 and goes up to 42.

Thanks for the help folks!

Brad

 

[Vettehead Mikey]

I'm finding out a lot of things about this car are not "stock"

UPDATE: I bought a new Street Fire Dist. and installed it and set the timing and wow, what a difference that makes! The engine runs 100 percent better! Way more power and throttle response. It even starts a little better too. My idle timing (with the vacuum advance plugged) is set to 10 BTDC and revved up stops at 32 BTDC. and with the vacuum advance hooked up it starts at 10 and goes up to 42.

Thanks for the help folks!

Brad

You're still about 4-6 degrees short on mechanical advance. Once that's sorted out you'll need another 4 on the vacuum too.

 

[Bombayduck]

Good info Mikey

There's a limiter plate thingy that came with the the street fire that screws on to limit the vacuum advance and I have it set to limit of 11 degrees max advance if my memory is correct. It has four settings and I have it on the second lowest to start with. I can put it on the next one up to get more vacuum advance.

On the mechanical advance I need to get lighter springs to swing the weights out further, right?

http://static.summitracing.com/global/images/instructions/msd-8362_frm30053.pdf

So after I do this I'll get even better performance?