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Cold Starting.
https://www.slantsix.org/forum/viewtopic.php?t=11257		 Page 1 of 2
Author:  Scat [ Wed Dec 22, 2004 6:06 am ]
Post subject:  Cold Starting.
I've been having a hell of a time starting my slant up. I've been able to start it at 5 degrees but other then that any colder and it won't go. My timing is off but that shouldn't be the problem. I've had a few choke issues until i converted to manual choke. I Have a carter bbs from a 1968 on a 83 slant 6 with a valve job. Its running a bit rich from what the plugs read. I have been able to start it with out the choke too a few times. I have thought about buying a block heater and using that but i have my doubts about it starting when i'm at school when i need to go to work or home. What would you guys reccomend

Patrick
Author:  Dennis Weaver [ Wed Dec 22, 2004 6:40 am ]
Post subject: 
...move south? :wink: :lol:

D/W

Sorry, couldn't resist! One of our Canadian members will be along to help shortly. :idea: :)
Author:  Slant6Ram [ Wed Dec 22, 2004 7:00 am ]
Post subject:  I can relate
It was bitter cold (around 10 deg f) on Monday. After sitting in the cold all night, my usual starting routine fell flat on it's face. I got good cranking speed, but it sounded like she was only hitting on half the fires.

I took the air filter off and noticed lots of gas around the choke plate. It seems like it had flooded, so I manually opened the choke back up and cranked till the flood cleared with the air filter off and not hitting the gas (which would reclose the choke) till it sounded like she was firing better.
The same thing happened after she sat in the parking lot at work all day.

Now this was really only a 5 minute task, but It's not a bit fun in subzero windchill playing under the hood with the choke. It also leads to the repeated "what's wrong with your truck now?" taunts from co-workers.

She starts perfectly when it's above 15 or 20 degrees f, so I am hesitant about making lots of changes to the choke adjustments.

I've had good results with placing an extension light with a 60watt bulb next to the block on cold nights, but that's only helpful if you have a safe place to plug in.

If you arn't getting enough cranking speed, you might look into buying a battery rated with more cold cranking amps.

A can of starting fluid (carried in your book bag) might be the warm kick she needs on the extra cold days.

Be sure the oil you are running is a winter weight (10w-30?)
Author:  Scat [ Wed Dec 22, 2004 11:25 am ]
Post subject: 
My battery is good to go it is rated at 630 cca but i did a battery test on it and it came out to be 843 cca's avalable. I will clean up all of my connections when i go home in a few. I have had the fuel problem with it loking like its flooded but its not. I think i'll buy a can of ether for the quick starts when i need to go. I am running 20w-50 oil but i better change that soon since i need a oil change. My truck has been running a bit rich too. I'll get back to you guys later.

Patrick :cry:
Author:  FrankRaso [ Wed Dec 22, 2004 5:08 pm ]
Post subject: 
Although I live in Canada, where I live could be considered the banana belt of the country. However, it does get somewhat cold here on occasion (-20°C / -4°F is not uncommon) and I haven't really had that much problem starting my car because of low temperatures.

As everyone knows, for an engine to run, it needs compression, fuel, and spark. Compression is rarely an issue so a starting problem involves either spark or fuel. If you make sure that the battery connections are clean, the sparkplugs are in good condition, and the cap and rotor are clean, you should have a good spark. The sparkplug wires usually last a long time so if you changed them recently, they should still be good. I find that the distributor cap gets a scale build-up on the inside terminals after a few thousand miles so a good scraping will make them fresh again.

It is easy to check for spark. Simply remove one of the wires from the plugs and hold it near a good ground. If you see a spark, you can safely assume that you ignition system isn't causing the starting problem.

Engines need the right fuel mixture to start. It can't be too lean or too rich. When the engine is cold, the fuel evaporates poorly so the carburetor is equipped with a choke to enrichen the fuel mixture. When the engine is warm, having the choke on will make the fuel mixture way too rich and the engine will become flooded.

The trick then is to have a good guess as to whether the engine is getting either too little or too much fuel to start. Generally, when the engine is dead cold, having the choke close fully which in turn kicks the throttle stop to the fast idle position will allow the engine to start. However, if the engine isn't really cold enough, the engine will not require the choke to be closed as tight. If your car isn't starting when dead cold, you need to figure out whether it's because it is getting too little or too much fuel.

A method I use for starting my manual choke equipped tractor is to start cranking it with the choke off. Gradually, while cranking, I pull the choke out until the engine starts. This takes a bit of practice as every engine is different. Anyway, once it starts, leave the choke on for a short time and then gradually start opening it.

For those people with automatic chokes, a starting problem occurs more often when the engine is partially warm. Either the choke is too open or too closed, but more often than not, it is too closed. I find that if I tap the gas pedal to set the choke and I try starting it, it sometimes doesn't start. After a few seconds of cranking, I suspect that it's not starting because the fuel mixture is too rich. I then immediately slowly push the gas pedal to the floor to clear the extra fuel. I push slowly to minimize the amount of gas squirted in by the accelerator pump. When the throttle is wide open, the choke plate is also partially kicked open and the engine always starts.

If you have to pump the gas a few times before you start, your choke needs adjustment. You should only really need to pump the pedal once to set the choke. A misadjusted choke also complicates starting the engine when it is half-warm. Anyway, if you find that you need to clear a flooded engine, simply press the pedal to the floor and crank until it starts.

As for the block heater, I don't have one but it is very common in the more frigid parts of the country. While living in Ottawa, I remember seeing electrical outlets in apartment parking lots so the people could plug their cars in overnight. If there is no place for you to plug it in, it is not going to be much help to you.

BTW, I was having a starting problem over summer which ended up being the result of a bad fuel pump. The old pump was not able to supply enough fuel while starting but supplied enough for the engine to run OK. A new pump after a total failure (in my driveway luckily) eliminated my starting problem.

Frank
Author:  Dennis Weaver [ Wed Dec 22, 2004 5:53 pm ]
Post subject: 
Quote:
...I then immediately slowly push the gas pedal to the floor to clear the extra fuel. I push slowly to minimize the amount of gas squirted in by the accelerator pump.
I know it makes us all feel like we're squirting less gas in that way, but in actuality, it is going to be the same amount of gas no matter how slowly we press the pedal to the floor. :idea: :lol:

D/W
Author:  sandy in BC [ Thu Dec 23, 2004 6:42 am ]
Post subject: 
We have some pretty good winter weather here in the Kootenays. Its never really cold enough to plug in the Valiant. Thats good because it has no block heater. My son Alex races boardercross at various ski hills in Western North America. Thats where it gets dicey.

First off: you need to change your motor oil to 10/30...20/50 will be too thick to even let the thing turn over at -30c and below.
I like to run ATF in a standard trans in the winter for the same reasons.

Dont use ether(starting fluid) unless you are way desperate. It washes the oil off the cylinder walls, can cause wild backfires and is better used recreationally(see Fear and Loathing)

Do a tune-up! Adjusting valves , idle mix, and choke setting takes an hour and makes a lot of difference. I adjust the choke so it just closes when cold. If the thermometer falls really low you need to readjust. As you have noticed the choke can be too rich when it gets colder.

You have a limited shot at getting it started. Have a plan and follow it.

Get a 100 ft extension cord and a little portable heater. A slant has lots of room to place the heater on the drivers side of the block. A 300 watt floodlight can also work. Infra red baby chick bulbs work as well.


Image
Author:  FrankRaso [ Thu Dec 23, 2004 7:11 am ]
Post subject: 
Thanks for the update Dennis.

I thought that the accelerator pump cup didn't seal really tight in its bore so a slow push would allow some leakage past the cup to reduce the accelerator pump shot.

Frank
Author:  Dennis Weaver [ Thu Dec 23, 2004 7:18 am ]
Post subject: 
Quote:
Thanks for the update Dennis.

I thought that the accelerator pump cup didn't seal really tight in its bore so a slow push would allow some leakage past the cup to reduce the accelerator pump shot.

Frank
...now I guess that's possible. Also, if you go slow enough, then some of the fuel might evaporate off... Sounds like a job for "mythbusters"! :idea:

D/W
Author:  FrankRaso [ Thu Dec 23, 2004 12:45 pm ]
Post subject: 
I think we both might be right. I was sure I remembered reading something about accelerator pump leakage so I leafed through some of my carburetor books. The Holley and Rochester carbs seem to have a more positive seal on the pump cup, unless they have a ball check valve on the pump. On Dave Emanuel's Carter Carbs book, page 32, the second paragraph of section "Accelerator Pump Circuit", I found:
Quote:
An accelerator pump serves to provide a quick shot of fuel anytime that the throttle is opened abruptly. The volume of fuel discharged through the pump nozzle or "squirter" into the air stream is determined by the amount and quickness of throttle shaft opening. The greater amount of opening and the faster the opening rate, the more fuel will be discharged. If the throttle is opened slowly, fuel is allowed to return to the float bowl rather than being pumped out of the discharge nozzle. And even though this functions similarly to a "leaky" pump, the leakage is controlled and is precisely the arrangement that's desired.
Whether the pumps shoots the same or less if you slowly open the throttle depends upon the design of the carburetor.

Frank
Author:  Dennis Weaver [ Thu Dec 23, 2004 1:20 pm ]
Post subject: 
I'll buy that. Now let's be the mythbusters and see what happens in the real world. I've got tons of AFB/AVS, BBD/S and holley 1920's to 'speriment with... Or does it really matter :?: :lol: I even open the gas slowly myself when clearing out a flood, even though I really don't believe that it makes much of a difference on a Carter! Just one of those things... I'm certain it doesn't hurt.

D/W
Author:  Scat [ Thu Dec 23, 2004 7:15 pm ]
Post subject: 
I think I got it fixed so far... I took off the air cleaner and it runs alot better from what i can tell. I also replaced the resistor on the ignition and its no more pop ing really just a quick start, I don't have to use the choke evene when it was -7 this morning. Its running a bit rich from the plugs but i can live with that( swaping to efi in spring) I'll get back to you guys tomorrow when its going to be about -11 and i'll see how she starts.

Patrick
Author:  SlantSixDan [ Fri Dec 24, 2004 7:52 pm ]
Post subject: 
If you can start the engine after several hours' sitting in even moderately cool temperatures without the choke, your carb is running WAY rich and you need to fix it. You should ALWAYS have to use the choke to start the engine after it's been sitting for more than an hour or so in cool-to-cold weather.

Timing also needs to be set correctly, for too much advance *or* too much retard will greatly aggravate hard-start problems.

If you improved things by taking off the air cleaner, you need to figure out what the problem is (air cleaner interfering with choke linkage? Clogged cleaner? Misrouted hoses?) and fix it. The engine needs an air cleaner, and when they're in proper repair they don't make or break the engine's ability to start when cold.

Starting fluid, engine heaters and light bulbs are band-aids, not fixes.
Author:  Scat [ Fri Dec 24, 2004 10:39 pm ]
Post subject: 
well it was around-22 last night and it started with ease with no choke, I'm guessing the spark wasn't as hot as it should be. I'm going to replace the ECU since its a 30 year old unit and the apoxy covering on the rear is cracking a bit. I'll put the air cleaner on tomorrow and see what happens wih the starting issue. I'm just planing on not putting anymore money into it untill i rebuild a short block.

Patrick
Author:  SlantSixDan [ Sat Dec 25, 2004 8:30 am ]
Post subject: 
If it started with ease with no choke at 22 (or -22), your carburetor is running insanely rich.
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