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73-87 Chevy _ GMC Trucks => Fuel Systems and Drivability => Topic started by: Joe-NC on December 07, 2010, 05:03:59 PM

Title: Starting a Carbureted Engine
Post by: Joe-NC on December 07, 2010, 05:03:59 PM
I'm used to my '02's injected engine cranking right up, so listening to the '84 turn over and over repeatedly before starting makes me cringe. What is the proper method for starting a carbureted engine on a cold morning?

Turn the ignition on and wait a few seconds? Pump the accelerator? Is it supposed to start on the first try?
Title: Re: Starting a Carbureted Engine
Post by: TandocTools on December 07, 2010, 05:13:24 PM
Depress the pedal fully once, let off all the way and start it up!
Title: Re: Starting a Carbureted Engine
Post by: VileZambonie on December 07, 2010, 05:14:42 PM
Depress the accelerator half way and crank the engine. When it starts remove your foot from the accelerator.
Title: Re: Starting a Carbureted Engine
Post by: TandocTools on December 07, 2010, 05:19:59 PM
I always heard that you depress it all the way to set the choke, but I defer to you!
Title: Re: Starting a Carbureted Engine
Post by: 1980c10 on December 07, 2010, 06:27:09 PM
I will check my owners manual to settle this, cuz now I'm wondering. I will post the results.
Title: Re: Starting a Carbureted Engine
Post by: 78 Chevyrado on December 07, 2010, 07:31:55 PM
A lot depends on how you have the truck setup.  once the trucks settings have been changed from how the factory set them, there's a good chance the factory instructions won't be just right anymore.  

on my 77 (350) you pressed the gas to the floor held it 2 seconds and let go and it fired right up.

on my 78 (350) press the pedal half way real quick let go and it starts right up.

on my 69 mustang (302) you had to hold the throttle 3/4 open until it started.

I finally got out and played with the edelbrock on my 78  and i got it tuned real good now.  Now on a 20 degree day, you just hit the gas half way let go and it starts, as soon as the gauge says the oil psi is good I drive off, and it doesn't stumble at all, has almost full power.   ;D

The main thing is that carbs are NOT a "set it and forget it" item, and new carbs are never ready to go right out of the box.  They may sound good, but they cannot possibly be dialed in.  they need tinkering as the weather changes to be just right.    fuel injected engines need the same thing but it has a computer to do its tinkering for it on the fly.

Title: Re: Starting a Carbureted Engine
Post by: 78 Chevyrado on December 07, 2010, 07:32:56 PM
I always heard that you depress it all the way to set the choke, but I defer to you!

You do have to move the throttle a little bit to activate the choke and fast idle.
Title: Re: Starting a Carbureted Engine
Post by: 1980c10 on December 07, 2010, 08:20:51 PM
from my 1980 owners manual
"cold engine
engine codes D, M, P, X, W and T-press the accelerator pedal to the floor and slowly release it. with your foot off the pedal crank the engine......
If the engine starts, but fails to run, repeat this procedure.
engine codes G, L, and R -press the accelerator pedal twice to the floor and slowly release it each time. Then, with your foot off the pedal crank the engine......
If the engine starts, but fails to run, repeat this procedure.
When the engine is running smoothly (about 30 seconds), you can reduce the engine idle speed by pressing down slightly on the accelerator pedal, then slowly releasing it.
Notice: If the engine runs a long time (5 minutes or more) without pressing down the accelerator pedal, overheating could cause damage to the engine and exhaust system.
warm engine
engine codes D and T -press the accelerator to 1/3 of its travel and hold. Crank the engine.............
Engine codes L, R, M, P, X, W and G -do not press down the accelerator pedal. With your foot off the pedal,  crank the engine...... If the engine does not start after 3 seconds , press down the accelerator pedal to 1/3 of its travel while cranking.
Title: Re: Starting a Carbureted Engine
Post by: 1980c10 on December 07, 2010, 08:29:30 PM
continued..paraphrased
very cold weather (below 0) or standing idle for several days. press and release the accelerator pedal 1 or 2 times more than stated for your engine under cold engine starting..............

If engine fails to start
1. fully depress and release pedal several times;..foot off pedal crank the engine....
2. if the engine still does not start, press the accelerator  pedal to the floor and hold it there while cranking. this should clear the engine if its flooded
3. if the engine has been flooded with too much fuel, it may start to run but not have enough power to keep running. in that case, continue cranking with the pedal to the floor until the engine clears itself of excess gasoline and runs smoothly.
Title: Re: Starting a Carbureted Engine
Post by: slammed79 on December 07, 2010, 08:52:26 PM
I guess I have my brothers 74 dialed in, I could let it sit for a week and it fires up on a single turn, and that's with no choke.
Title: Re: Starting a Carbureted Engine
Post by: velojym on December 07, 2010, 08:58:05 PM
Mine pops right off so long as it hasn't been sitting for more than a week or so. More than that and I have to pump it a few times (accelerator pump shoots a prime charge in) and she's fine after that.
As for tuning my Edelbrock carb, I have a lot to learn yet.
Title: Re: Starting a Carbureted Engine
Post by: 77c10diesel on December 10, 2010, 09:16:58 AM
Every truck is different. I had an old F@&D that you got a work out pumping the peddle before you could start it.