The Stovebolt Site Forums The Shop Area Engine Shop Answer me this one......

I've been reading the forums for a long time and I've never seen this question asked, so here goes ........

Sometimes I have to crank and crank and crank the motor and it just won't start. Somebody please explain to me why if I then point it down hill, and get it rolling then pop the clutch, it starts immediately?? Makes absolutely no sense to me, but there's got to be an explanation.

Low Compression?

Low compression is a possibility, another possibility is while cranking the battery voltage drops to the coil too low for it to create spark. What year model, engine and voltage?

Is it worse HOT or Cold??

Empty carb when starting and the fuel pump has to fill the carb??.....maybe fuel pump is going bad?

Downhill the gas is gravity feeding and helps fill the carb faster??

Cold starts dry carb?...... Hot starts low compression? ....or starter dragging when hot with high compression on the engine?...hot and vapor locked??

If you let it roll off down hill when its cold does it start right up??


.....just throwing stuff out there.

an explanation . . .

there are many possible explanations . . .

poorly adjusted carburetor and/or timing?

. . .

Rolling down the hill and dumping the clutch results in much higher RPM, overcoming the lack of compression from worn rings, or flooded conditions.
That is why running a 6 volt starter on 12 volts is such a popular option. The 6 starter will turn the engine over much faster on 12 volts than it does on 6 volts, thus increasing RPM and overcoming lack of compression from worn rings, or a flooded condition.

Carl

As it's approaching dark, pull the coil wire out of the coil a bit and have someone crank it over. If the spark is a weak kinda yellow I'd suspect low voltage to the coil. Check all connections.

Good Luck, Ron

Here is my story when I first got my truck nicely painted rebuilt motor nicely painted,when the truck was cold would crankmover and start okay once warm would not start unless I rolled and popped the clutch. I disc covered the ground strap were it attached to the nicely painted motor was not making good d contact. I know long story to say I had a bad ground.

Low battery voltage. I'll bet you're running a 6 volt system, right? While you're cranking with the starter the voltage will be down around 4 1/2 to 4 3/4 volts, and the majority of the battery current is going to the starter. That leaves very little to power the coil. A roll start spins the crankshaft with the weight of the vehicle, and the ignition system is getting 5 1/2 or 6 volts to the coil. Hotter spark- - - -the gas lights off better.

Check the connections at the back of the ignition switch and the wiring to the coil- - - -I'll wager you're going to find some loose, dirty connections, or an ignition switch with bad internal contacts. A slightly dirty set of points will cause the same problem.
Jerry

It always harder to start when it's hot. You'd think it would be just the opposite!

I usually don't have to travel but 10-15 feet before I pop the clutch, so I don't think the RPMs are high.

I usually use 2nd gear so it doesn't jerk me and the truck too hard when I let off the clutch. Always fires right up.

The 216 has 97K on it and I have no idea what, if anything, has been done to it during its lifetime. It *does* smoke a bit while running.

I've noticed the fuel filter isn't always full of gas, especially when it's cold. I always set a full choke when I first start it cold. If it's hot and it doesn't fire on the first attempt I always have to pump the accelerator several times and choke it to make it start. If the 2nd or 3rd attempt doesn't work the 6v battery gets weak and that's when I have to roll it downhill and pop the clutch.

Thanks so much for all the suggestions. I'll take a look at all the electrical connections and spark at the coil tomorrow.

Drop me a PM and I'll try to walk you through some checks to find where you might be losing voltage to the starter and/or the ignition system. I drove a 47 Mercury for years with over 11:1 compression and a 6 volt electrical system!
Jerry

I agree with Jerry. How thick are your cables coming off the battery? Bigger in diameter the better.

I had this exact issue, 0/0 cables, rebuilt and tuned generator and voltage regulator, and Optima battery, no more issues.

.........."I've noticed the fuel filter isn't always full of gas, especially when it's cold."

..... ..."If it's hot and it doesn't fire on the first attempt I always have to pump the accelerator several times and choke it to make it start."

Hmmm, this should also tell us something.

What HRL said! I would add a compression check to the list just to see where you are.

I used to spend at least an hour of classroom time on the history and design of electric starters. The Cliff's Notes version goes like this: Starters operate at what is essentially a dead short- - - - -resistance down in the 1/100ths. of one ohm. The only thing that controls the current flow in a starter is something called "Back EMF", the tendency of a spinning armature to generate a voltage opposing the current flow to ground. The slower a starter turns, the more current it draws from the battery. Since electrons follow the path of least resistance, if the starter is hogging all the current, systems like the lights, ignition, etc. don't work at all or at least they don't work well. It's like following the fat, greedy guy down a buffet line- - - - -you might leave hungry!

Trying to run an ignition system while a slow-turning starter is sucking up all the juice is like trying to water your lawn when there's a big hole in the water main out in front of your house- - - - -the pressure just isn't going to be there to run the sprinkler. It's vitally important to make the starter turn as fast as possible so there can be some voltage left in the battery to power other systems.
Jerry

You guys have been awesome, and I can't thank you enough for helping me! And thank you Jerry for giving me, and all of us, an education about the electrical side of my question! Your comments are sprinkled all over the Forums, and I learn something new every time I read them. I'll take you up on your offer for a one-on-one conversation.

Thanks again *everyone*!

Have you tried pouring a small amount of gas into the carb throat before attempting to start your truck ?

Sounds like you have multiple issues going on at once, which always makes troubleshooting "fun". Hotrod is your man. He'll help you sort them out.
As far as RPM during a push start in 2nd gear (3rd for that matter), you will definitely have much more RPM than what your six volt starter will provide.
Another aspect of the efficiency of push starting and its resulting higher RPM is the dynamics of rotating mass (crankshaft, flywheel).
Physics dictates that a body in motion tends to stay in motion. The increased speed of the motion of these heavy rotating parts is what makes push starting easy to do.

I just hope Jerry is working on his book of automotive expertise. I'll buy the first ten copies. Good stuff!!!

I'll buy the next 20!!!!

Jerry's theory is very easy to prove if your truck still has a stomp starter. There are two wires on the starter terminal; the battery cable and the main feed wire. Take these off and hook back together with a short bolt and wrap with something to prevent arcing. Now set a 12v battery close enough to the starter so a cables can run to the starer and to a good ground. You now have a 6v truck with a 12v starter and 100% of the voltage is going to the ignition system. This was a trick used back in the days of old rope seals which could really make a brand new engine hard to turn over. After starting and running in with this set up a couple times the engine would then turn over with the regular set up.

Evan, in the late 1940's when Perfect Circle came up with the idea that worn piston skirts could be knurled to minimize piston slap during an overhaul, they intentionally tried to over-knurl a set of pistons to see if somebody could damage an engine that way. They built up a flathead Plymouth engine and knurled the piston skirts to .005" over the bore size. They had to drive the pistons into the cylinders with a big hammer and a block of white oak, and the starter wouldn't begin to turn the engine over.

They filled the trunk with sandbags for traction and got the engine started by shoving the car down the block with the push bar on a big wrecker. It took full throttle in first gear for a few miles to keep the engine running. Eventually things loosened up enough to shift to second, and then third. They were a long way from their research shop when the gas tank ran low, and they had to shut the engine off to fill the tank. The starter cranked the engine properly, they drove back to the shop, and one of their researchers put several thousand miles on the car before they tore it down for an inspection. No ill effects whatsoever from the over-knurling. I still knurl pistons occasionally, and it still works!
Jerry

It may be possible you do not have power you your ignition system when cranking but do when not cranking. Check spark while cranking to verify

Check battery voltage when cranking-that will tell all.

Ed

I had a voltage regulator go bad giving me low battery voltage to begin with......things just got worse from there.

Well, one thing I've noticed since I got the new battery is that it fires right up when I hit the stomp starter! Hotrod Lincoln and Roy Rogers were right...... after spinning the starter there wasn't enough voltage left in the old battery to energize the coil. The engine wasn't getting a hot enough spark to light the gas. Looking back, it's been hard to start for a long time, so the battery has been the culprit all this time!

yup, a new battery can do wonders..