Cadillac & LaSalle Club Discussion Forum

Cadillac & LaSalle Club Forums => Technical / Authenticity => Topic started by: Jim Miller on March 13, 2023, 10:24:45 PM

Title: 1970 flooding issue?
Post by: Jim Miller on March 13, 2023, 10:24:45 PM
My 70 will start easily after one or two depressions of the accelerator. I can immediately put her into drive with no issues or hesitation. But after a few moments she loads up with fuel. Left to idle, she'll stall. I'll need to fully depress accelerator to restart. Or if I put into neutral and work the accelerator she'll keep running. Once warm the car runs perfectly. I'm assuming a choke issue, but I've learned to solicit input first in case there is something unique to the '70 that those of you more experienced owners will know.
Title: Re: 1970 flooding issue?
Post by: signart on March 13, 2023, 10:45:08 PM
Does sound like a choke issue. Remove the breather and work the linkage and give them a little oil, check for binding. Start it normally and watch the choke as it opens when the engine warms.
Title: Re: 1970 flooding issue?
Post by: CadillacFanBob on March 13, 2023, 10:55:00 PM
Look at vacuum choke pull off operation, lube linkage , and test vacuum chamber with vacuum pump tester

Bob
Title: Re: 1970 flooding issue?
Post by: TJ Hopland on March 14, 2023, 01:16:15 AM
Pull off seems like the first place to check to me too.  If you have the lid off the air cleaner as soon as it starts the choke should instantly open about 1/4". 

If you have a hand vacuum pump you could test that on a cold engine.  Stroke the throttle which should basically lock the choke shut.  If you then operate the vacuum pull off (or start it) you should get that 1/4" opening.  After that its up to the thermal coil thing to open it the rest of the way over the next several minutes which sounds like is happening so that is why the pulloff is the place to look. 
Title: Re: 1970 flooding issue?
Post by: Chopper1942 on March 14, 2023, 08:25:41 AM
Don't put oil on the linkage.  Get some choke/throttle body cleaner and spray the linkage. This will leave the linkage dry and it will not attract dust that will cause it to hang up.
Title: Re: 1970 flooding issue?
Post by: Dave Shepherd on March 14, 2023, 10:51:57 AM
If not a choke problem, could be a sunk float.
Title: Re: 1970 flooding issue?
Post by: Cadman-iac on March 14, 2023, 01:52:30 PM
Quote from: Dave Shepherd on March 14, 2023, 10:51:57 AMIf not a choke problem, could be a sunk float.
That's possible, but in my experience, when a float is saturated, it usually causes flooding all the time.
 As I've said before, if your float don't, get a new one.
Title: Re: 1970 flooding issue?
Post by: Chopper1942 on March 21, 2023, 12:16:51 PM
If the carb is a QuadraJet,  the main well plugs may be leaking when it sets and is cold.  To fix this issue, you need to take off the carb base, turn the carb body over, clean off the lead well plugs in the middle of the bown, and put a small amount of epoxy over the lead well plugs in the bottom of the bowl.

This should be done any time a QuadraJet is cleaned/overhauled.

Still, sounds like a choke  issue.
Title: Re: 1970 flooding issue?
Post by: TJ Hopland on March 21, 2023, 12:37:35 PM
I wonder if he has had a chance to look closer at this issue yet?
Title: Re: 1970 flooding issue?
Post by: klinebau on March 21, 2023, 12:40:20 PM
Leaky well plugs affected only the very first Quadrajets.  The plug and swaging process was changed and this problem was fixed by 1969 (or earlier).  While it is technically possible to have leaky plugs in later models, it is not likely.
Title: Re: 1970 flooding issue?
Post by: TJ Hopland on March 21, 2023, 01:04:53 PM
Leaking plugs or a float issue really don't fit his symptoms.  He says it starts fine then after a few moments loads up.  Then once it gets past that its fine. 

Leaking plugs cause a starting issue and you usually eventually get a rough start but after a moment it cleans up and then is fine, pretty much opposite what he says is happening.

On the float front unless he has an electric pump its not going to leak while the engine isn't running and even if it did it would tend to cause starting issues.  Electric or mech pump and a float issue would likely continue to be a problem at a warm idle which he says isn't the case.

The choke pull off really fits his symptoms.  Engine will fire with the choke completely shut but if it doesn't slightly open as the engine starts it can't get enough air.  The reason it eventually cleans up is the thermal action eventually starts to open it so that is why at some point things go back to normal   
Title: Re: 1970 flooding issue?
Post by: Jim Miller on March 21, 2023, 10:09:54 PM
Thanks for all the input. I've not yet tackled it. I made the initial post then left for a bucket list cruise of the Panama Canal. Trying to get caught up this week.
Title: Re: 1970 flooding issue?
Post by: Chopper1942 on March 22, 2023, 01:51:22 PM
As I stated in my last post, he has a choke issue.  Without actually seeing the vehicle it is difficult to tell him what needs fixed.  It could be a bad diaphragm in the vacuum brake (most likely), vacuum brake misadjusted, vacuum brake connected to ported vacuum, choke spring is wound to tight.

The '65-'68's Q-Jets had many problems.  The diaphragm needle finally changed to a needle and seat, porous floats, fast idle cams cracking, and very poor fit of the well plugs. These issues were all fixed and Q-Jet became a very good carb both for economy and performance.

Leaking well plugs can still be an issue.  Any time I overhaul any carb that has well plugs, I seal the plugs as a preventive measure.

In the past, I have fixed many customer's compliant of poor fuel mileage by sealing the well plugs on Q-jets and other carbs.  When they just sit, they usually do not leak.  When the engine is started and vacuum is applied to the well plugs the fuel seeps past them. If the well plugs leak, when just sitting, bad enough to cause a "flooded" start, the engine is going to be extremely rich and probably smoke when driving.

Title: Re: 1970 flooding issue?
Post by: Jim Miller on March 22, 2023, 05:09:14 PM
Pulled air cleaner off and took another good look before starting anything. The linkage between the pull off and the carb just didn't look right. Compared to photos off internet and it was not on correctly. Went ahead and checked the pull off itself and it worked fine. Put everything back together and put the linkage on correctly. Car started and didn't load up.
Title: Re: 1970 flooding issue?
Post by: TJ Hopland on March 23, 2023, 02:40:48 AM
Well that was easy. 30 years ago you would have to hope someone close by had a similar car to look at or go to the public library and look for a book to figure out what it was supposed to look like. At least that is how I did it after I took it further apart and made it worse which meant I was riding my bicycle to the library with a pocket full of change for the photocopier since the good manuals were reference only. 
Title: Re: 1970 flooding issue?
Post by: Jim Miller on March 23, 2023, 08:17:07 AM
Quote from: TJ Hopland on March 23, 2023, 02:40:48 AMWell that was easy. 30 years ago you would have to hope someone close by had a similar car to look at or go to the public library and look for a book to figure out what it was supposed to look like. At least that is how I did it after I took it further apart and made it worse which meant I was riding my bicycle to the library with a pocket full of change for the photocopier since the good manuals were reference only. 
Yes Indeed! With the internet, you tube, and this forum I've saved a lot of time and money and kept myself from doing something stupid.
Title: Re: 1970 flooding issue?
Post by: Dave Shepherd on March 23, 2023, 08:37:10 AM
This is where we are at a disadvantage not being onsite to see what's what, when trying  to give meaningful  advice.
Title: Re: 1970 flooding issue?
Post by: klinebau on March 23, 2023, 08:49:53 AM
In the service manual, there are specific instructions and measurements for adjusting the linkages.  It involves bending some levers and tangs, but isn't hard.  I remember when doing this after I rebuilt the carb and was amazed how well it started even in pretty cold weather.
Title: Re: 1970 flooding issue?
Post by: Chopper1942 on March 23, 2023, 02:49:32 PM
If you can't find the specs, give me the carb number and I will check my line 9 manual of info. on the setup for the carb.