1969 Rocket 350 with Late 70s GMC truck Quadrajet, cold start problem
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Joined: May 2013
Posts: 135
From: Vancouver, British Columbia, Canada
1969 Rocket 350 with Late 70s GMC truck Quadrajet, cold start problem
Hey guys wondering if anyone has any advice for me here, but first a quick rundown of what I'm working with.
One the car has been started once during the day it fires up effortlessly
I have a 1973 Oldsmobile Omega, with a 69 Rocket 350 swapped in, that has a late 70s I cant remember exactly what Quadrajet off a GMC truck on it.
I have rebuilt the carb myself and I'm pretty sure everything is ok on it, the well plugs are good, I bought a thermostatic coil for the carb and fabbed up an adapter plate and bent an old choke rod off a duojet to size to that it could function on my Olds intake manifold. So the automatic choke seems to function ok, and also I did the thing where you bottom out the rod then measure it to make sure its sitting in the right place or whatever.
Fast idle works correctly and is set at the right RPM.
I had an issue where the parts store gave me plugs for a 73 Engine and they were causing starting troubles, I also had a failing ignition switch that would make the car only want to start when releasing the key and I Replaced that, the wrong plgs made it so I had to run a fairly rich idle mixture as it was still too rich even after seting it with a vacuum gauge which was causing a bog going onto the throttle sometimes. I swapped the plugs and now the car fires up great as long as its been ran that day at some point. Even if it sits long enough to get cold again just gotta pump it once to set the choke/fast idle and she starts up fine. I managed to get the idle mixture down to a more proper setting but it might still be a little rich?
The problem is ill go to start the car in the morning, one pump wont be enough to get it to crank, it seems to want either 2 or 3. It will fire up try to get up to fast idle but bog and stall after a second or two. I will have to repeat this one or two more times but eventually it will start up and idle steady until it clears up enough to get to fast idle and then will warm up and run fine afterwards.
I'm thinking perhaps the idle mixture is too rich and flooding the carb when its cold? Or maybe the well plugs I sealed up a few months ago are leaking again for some reason?
I had the idle mixture set with a vacuum gauge but I havent tried doing that again since I changed the plugs so perhaps I'll try it again? Everything on the carb seems to function flawlessy apart from the first time I go to start it in the morning.
I've tried pumping it 3 ,4 ,5, 6 times and more fuel doesnt seem to make the problem better, that combined with the fact that the engine wants to bog a bit when first starting makes me think maybe the idle mixture is too rich?
One the car has been started once during the day it fires up effortlessly
I have a 1973 Oldsmobile Omega, with a 69 Rocket 350 swapped in, that has a late 70s I cant remember exactly what Quadrajet off a GMC truck on it.
I have rebuilt the carb myself and I'm pretty sure everything is ok on it, the well plugs are good, I bought a thermostatic coil for the carb and fabbed up an adapter plate and bent an old choke rod off a duojet to size to that it could function on my Olds intake manifold. So the automatic choke seems to function ok, and also I did the thing where you bottom out the rod then measure it to make sure its sitting in the right place or whatever.
Fast idle works correctly and is set at the right RPM.
I had an issue where the parts store gave me plugs for a 73 Engine and they were causing starting troubles, I also had a failing ignition switch that would make the car only want to start when releasing the key and I Replaced that, the wrong plgs made it so I had to run a fairly rich idle mixture as it was still too rich even after seting it with a vacuum gauge which was causing a bog going onto the throttle sometimes. I swapped the plugs and now the car fires up great as long as its been ran that day at some point. Even if it sits long enough to get cold again just gotta pump it once to set the choke/fast idle and she starts up fine. I managed to get the idle mixture down to a more proper setting but it might still be a little rich?
The problem is ill go to start the car in the morning, one pump wont be enough to get it to crank, it seems to want either 2 or 3. It will fire up try to get up to fast idle but bog and stall after a second or two. I will have to repeat this one or two more times but eventually it will start up and idle steady until it clears up enough to get to fast idle and then will warm up and run fine afterwards.
I'm thinking perhaps the idle mixture is too rich and flooding the carb when its cold? Or maybe the well plugs I sealed up a few months ago are leaking again for some reason?
I had the idle mixture set with a vacuum gauge but I havent tried doing that again since I changed the plugs so perhaps I'll try it again? Everything on the carb seems to function flawlessy apart from the first time I go to start it in the morning.
I've tried pumping it 3 ,4 ,5, 6 times and more fuel doesnt seem to make the problem better, that combined with the fact that the engine wants to bog a bit when first starting makes me think maybe the idle mixture is too rich?
Thread Starter
Registered User
Joined: May 2013
Posts: 135
From: Vancouver, British Columbia, Canada
Of course I figured it out right after I posted this.
I forgot that the rod I made that goes from the thermostatic coil to the choke on the carb would sometimes bind a little bit so I greased it up, well that was a few months ago so now in the morning when I would pump the gas it wouldnt slide all the way to full choke.
I shut the car off while it was still cold and let it sit for a few minutes then made sure when I pumped it it went to full choke and it fired right up.
I greased it in the meantime but later today I'll probably take the coil off so I can take that rod to the grinder or file it down a little so that it can move freely.
I forgot that the rod I made that goes from the thermostatic coil to the choke on the carb would sometimes bind a little bit so I greased it up, well that was a few months ago so now in the morning when I would pump the gas it wouldnt slide all the way to full choke.
I shut the car off while it was still cold and let it sit for a few minutes then made sure when I pumped it it went to full choke and it fired right up.
I greased it in the meantime but later today I'll probably take the coil off so I can take that rod to the grinder or file it down a little so that it can move freely.
Out of Line, Everytime😉
Joined: Dec 2006
Posts: 10,104
From: Melville, Saskatchewan
That should be the choke pull off opening too much. The later carbs have an adjustment screw, sounds like it needs closed up a bit. Assuming the choke is closing, sounds like it isn't. My car with no choke plate acts exactly like what you explained in cold weather.
Thread Starter
Registered User
Joined: May 2013
Posts: 135
From: Vancouver, British Columbia, Canada
That should be the choke pull off opening too much. The later carbs have an adjustment screw, sounds like it needs closed up a bit. Assuming the choke is closing, sounds like it isn't. My car with no choke plate acts exactly like what you explained in cold weather.
The fast idle I cranked way too high though I thought I screwed up setting the idle when I took it a short drive up to the store as it wanted to idle around 1100 in drive but as soon as I came back after shutting it off and it being parked for a few minutes it fired up normally, I guess the choke was still a bit closed as the car had probably only been running for less than 10 minutes all together including sitting to warm up and that combined with the fast idle being too high made it do that.
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