Cool runnings

[Jeff Balazs]

I've been working on getting all the little things adjusted/sorted on my truck. One thing I have noticed is that it is very cold blooded. Seems to take an age to warm up. First minute or two running it is fairly easy to stall. I wonder if my carb is not set exactly right?

When warm I get a reading of 20.5 on the vacuum gauge at idle. Timing has been set to obtain high vacuum reading.

 

Don't know whether this is just normal but it takes about 10 minutes or so to reach 160 degrees and another couple to get to 180 degrees and have the thermostat open. Also now that it is a little cooler starting drill has changed. During the warmer months I set the choke pumped the gas once and hit the starter and Bingo. Now I do this briefly and it doesn't quite start. Push in the choke and hit it again and she fires up first or second try. If the choke is on it just wont start......but if I turn it over a couple revolutions with the choke set it seem to prime thing for a try without the choke. And if I don't use the choke in this manner it doesn't seem to want to start. Not sure what to make of this? It does always start and it is not that cold here so I am uncertain why this has come about.

Ideas and suggestions appreciated.

 

Jeff

[48Dodger]

Since it does run......check your plugs and see if your getting a good reading. Also make sure your spark plugs are in the right heat range for your engine. Just a few thoughts off the top of my head.

 

48D

[Dave72dt]

Record what your timing is set at and then back it down a couple degrees. Also check your vac advance for proper functioning. You could try pumping the pedal twice before turning it over.

[HanksB3B]

It has nothing to do with anything mechanical. It's a Mopar thing more or less how your truck feels about you. My old car,  a 1958 Plymouth Fury acted the same way.

 

 

 

O.K. on a more serious note: I find that how I shut down my engine influences how it starts up. Letting it idle down and parking on a flat surface almost guarantees that turning the ignition and pressing the foot starter without messing with the choke or the throttle will almost always fire the truck right up. If that doesn't work pulling the choke out about 3/4' of an inch and giving it two or three pumps on the pedal with the throttle pulled out about an inch will start the truck on the first or second crank. Sure go ahead and check the point gap, if your carburetor has never been rebuilt it's worth looking into and knowing the look of the spark plug tips and like Tim says the heat range can make a difference. I've always used Autolite 306 plugs. I'm sure with your vintage engine skills you'll figure it out.

 

Hank   

[JBNeal]

FWIW:  on cold flatheads (especially in temps below 50F), full choke, 1/4 throttle, stomp the gas 2x, crank the starter; upon engine fire, reduce choke to 1/4 and have throttle just cracked open to get idle rpm to about 1000 until the thermostat opens, then reduce choke to 0.  In electronic fuel injection systems, the cold engine is in open loop mode, requiring a more rich fuel mixture to optimize power.

 

Once the engine has warmed up, further engine re-fires shouldn't require choke and little to no throttle input, depending on ambient temperature.  From what I've seen, automatic choke operates off of engine manifold heat, an early form of open loop engine controls.

 

One of the driving instructions I was given by Dad was to drive the truck with the 1/4 choke when it was cold.  Without 1/4 choke, the truck will idle fine, but stumble upon acceleration.  With the increased rpm & 1/4 choke, the engine will warm up faster.  Consulting the shop manual, there are different carb settings that will control the stroke of the accelerator pump lever, allowing for more fuel delivery with the winter setting.  With the winter setting, maybe not so much throttle is required at cold startup.  I might try that someday...without a heater in the truck, I'm not too motivated to drive the beasts when it drops below 40, so I'm on the intermediate setting year round 

[Don Coatney]

Accelerator pump settings. The inner hole (shown) is the short stroke for Summer. Outer hole (not shown) is long stroke Winter setting.

 

[Don Coatney]

Trucks may be different but on my car there is also a high idle cam that holds the idle higher when the choke cable is pulled. To set the high idle I must pull the choke cable and at the same time push the throttle foot feed. This sets and holds the high idle. To drop the idle down to normal I must push the choke cable all the way in and then tap the foot feed. There are also two speed adjustment screws. One for normal idle and the other for high idle.

 

[Don Coatney]

This might or might not help.

 

[TodFitch]

The purpose of the heat riser is for better cold start drivability which sounds like what you are having issues with. . .

[Frank Elder]

Or the simple fact that you have a lot of iron to warm up.......it's going to take longer during cold spells.

Edited January 8, 2014 by Frank Elder

[55 Fargo]

My garage can be about 35 f, I pull choke on full, hit the stomper, fires right up open choke to 1/2 way, just about every time is like this for a cold start.

Now mine is 12 volts, and they just start better, no doubt about it.

I can drive truck in a few minutes in 30 below, no bucking runs pretty smooth even when cold. My truck will heat up very quickly to 160f  t/stat is doing it's job.

My truck has a throttle cable, no fast idle cam associated with the choke.

Edited January 7, 2014 by Fargos-Go-Far

[Young Ed]

Or the simple fact that you have a lot of iron to warm up.......it going to take longer during cold spells.

 

Also a mechanical fan constantly throwing air around makes a difference over a newer car with a thermostat controlled elec fan. My 94 dakota with a mechanical fan takes a long time to warm up. I have plastic filler pieces in the grill and it still takes a good 15min to get warm.

[wallytoo]

Trucks may be different but on my car there is also a high idle cam that holds the idle higher when the choke cable is pulled.

i believe the trucks are different, don.

jeff, fwiw, there's a lot of different ways to get these to start, and a lot depends on the condition of the components, etc. my 237 fires up easily in cold weather (i've had no problem starting it in sub-zero temps), and i only use about 1/2 choke, press the gas twice, and set the throttle to about 3/4" on the dash. then press the button, and it starts. after i idle for about a minute, i drive off, with the choke at maybe 1/4th setting for about 5 minutes. the heat riser IS important for driving soon after starting.

[Jeff Balazs]

Hi Guys;

Thanks for the suggestions. Just to clarify I have fitted 306 plugs and they look just fine. The heat riser was rebuilt and is functional.

And it is not cold here like a lot of you have been having......it was 55 at 6 am.

 

I will take a look at the timing......could be off a bit but she pulls well after a couple of minutes running time. I have a feeling that the carburation is off a bit.

It was starting just as sweet as could be late this summer. A touch of choke.....one pump on the gas pedal......and hit the starter. Then all I did was push the choke in and it did not seem to be too sensitive. Now when it starts it requires more finesse on the gas pedal for the first minute or two. And it doesn't want the choke at all. Not sure what I have changed to make this difference

.

I wonder if a session on an exhaust gas analyzer might give me a better picture. My engine is a 54-56 series 230 that came out of a C-1-FL type truck but it is fitted to a fluid drive and has a DTG1 carter that probably came off the original 218. Don't know if it is jetted correctly or if anyone has the info to select or at least verify the jetting? One thing I can try is what Don suggested on the accelerator pump linkage.....I just never  thought our weather would require fiddling with this sort of stuff.

 

I am not expecting this truck to behave like a modern car but I would like to get it as close to optimum as I can. I am happy to wait a few minutes for warm up....after all God only knows how long it waited for me to come along and breath some life back into it.

 

Jeff

 

Ps.....I went ahead and reset the timing this morning after it had warmed up. Was a bit advanced so we will have to see if that makes a difference next cold start.

Edited January 8, 2014 by Jeff Balazs

[Jeff Balazs]

Interesting.I reset the timing back to spec yesterday and tried starting it as I was a while back......and low and behold it fired and caught right away. I doubt it I cranked it more than a revolution. So starting procedure has a lot to do with how the timing is set. Starting drill is ignition and fuel pump on....set choke and pump pedal once....then a brief tap on the stomp starter. Choke can be pushed back in after start. Reading on vacuum gauge is a shade under the 20" mark now at idle.

These are fairly cold blooded though......it is a good 5 minutes before the temp needle starts to move up. And that is if I leave the electric fan off. I ditched the standard fan 6 months ago. It still takes a couple of minutes of running time to stabilize idle and have decent throttle response......but I think I can probably learn to live with that.

 

I remember now that I adjusted the timing a little while back when I installed the permanent vacuum gauge. I set it based on highest reading which once warm seemed to have very good throttle response. But it definitely made starting fussier. Oh well....live and learn.

 

Based on this result I think I will just leave the accelerator pump rod where it is at .......unless there is really evidence that some benefit could be made by messing with this? I would still like to get the truck on an exhaust gas analyzer to help determine if it is indeed jetted correctly. It smells rich to me and there have been enough changes made on it that it could be a ways off.

 

Jeff

[MBF]

I'm not sure where you are located, but depending on how cold it gets at your location could have an effect on things.   Cold air is more dense and will require slightly more choke during a cold start to get the starting air/fuel mixture the same as what you have during warmer seasons.  There is also a lot of iron to heat up to operating temperature.  If you have installed a pcv system, that will also effect the starting process as it could create an overly lean mixture due to the fact that it is basically a controlled vacuum leak.  Plug and point gap may also effect starting.   Mike

[Jeff Balazs]

Hi Mike;

I think you hit it on the head.....it is a lot of iron to heat up! Adjusting the timing seems to have done the trick as far as a quick start goes. I am in coastal southern California so real cold is just not a factor. Clear and mid 70s today. If I leave the electric fan off for the first few minutes it does seem to warm up slightly faster. It is on a manual switch for now. I will have to look a bit closer at perhaps adding in a thermostatic control of some sort. So far I have not added any electronics to mechanical system of this truck.... and I really don't want to....but this cooling fan control may be one item I have to. On the plus side the electric fan even if left on the whole time the engine is running is much quieter than the stock fan.....isn't in the way when setting the timing .....and can't bite any fingers.

 

I did have a PCV system connected earlier on but I could not get it to behave to my satisfaction. It is off now and I am just running the road tube. I will probably revisit this PCV system installation once I have gotten some other stuff sorted out. As with so many items on my not quite original truck it did have a cobbled together PCV arrangement but I have no idea if it worked correctly or if any jetting mods were made. I have components I got from VPW and when I tried it I think the valve itself was not working correctly.

 

Jeff