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Old 07-31-2016, 08:13 AM   #1
Kneadabagel
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Default C120 won't start

Straight six turns over. Gas pedal was stuck so we removed carberator and freed up all rusty parts. Put back together and still won't start. Looks like a new distributed was put in. Checked the ignition coil and not getting the same charge as the battery. I am a novice as you can pretty much tell. Any suggetions??? Thanks
micah
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Old 07-31-2016, 09:41 AM   #2
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Default Re: C120 won't start

Welcome to the forum. Since this is a tech question not pertaining to the show section you posted it to, I moved it to a more appropriate place. No harm done. For best results with future posts, just make an attempt to post them to the most appropriate subject heading.

Now, let's have some more back story if you can provide it. How long has this truck been in your care? Do you know approximately how long its been since this engine last ran?

Three things are required in proper amount and at the right time for internal combustion to occur. They are air, fuel and spark. I gather that the starter motor is capable of rotating the engine over (cranking) when you hit the switch. As long as you're able to breathe, we can assume that the air leg of the combustion pyramid is covered.

Next leg is fuel. Is clean, fresh fuel getting to the carb and then to the spark plugs? Do not be trying to start this thing on varnished gas from the nixon administration. If the fuel tank and fuel lines aren't whistle clean, you should be temporarily bypassing them in favor of a fuel can with a fresh supply. You removed the carb and freed up rusty parts. Does that mean you completely disassembled it and thoroughly cleaned all the internal passages, and installed a rebuild kit? If not, that's probably something that ought to be done if this rig has been hibernating since moses was in diapers.

Last leg of the pyramid is spark. What makes you think a new distributor was put in? How do we know it is the correct one for the engine? We should probably operate under the assumption that whoever replaced whatever combination of spark making parts did something wrong at some point. That May not be so, but we can't afford the luxury of assuming things are hunky dory here. Better to suspect foul play and be pleasantly surprised, than to blissfully stumble along in ignorance.

That means you need to verify the spark plug wires are routed correctly in accordance with the engine firing order, as cast into your manifold. Firing order can also be found in the factory service manual for your vehicle. You have one, right? Better get one if you don't. IH parts, the purveyor of this tech forum, has them available for purchase.

Since there is a chance that the distributor was out of the engine and reset, you need to verify that the static spark timing was set correctly. There is one cylinder of your engine designated for timing adjustments. Probably #1 with the 6-poppers, but I don't know that for certain. I'm well versed with the IH sv8 engines, but not at all with the sixes. IH did a few things differently than the other makes. Whatever cylinder is designated for timing, when it is placed at top dead center on the compression and not the exhaust stroke, the rotor button will be resting beneath the cap tower location that is adjacent to the plug wire going to that designated cylinder. Then the remainder of the plug wires must be routed in accordance with the firing order, in the proper rotational direction (usually clockwise) around the cap. You also need to know what the static timing factor is. Is it 0 degrees of advance, or 4 degrees btdc? I don't know. Again, that is valuable information that can be found in the manual. While the cap is off, have a look at the breaker point set. Are the contact surfaces clean and flat? Was the gap and thus the dwell angle set correctly? This needs to be checked. The point gap can be found in...you guessed it...the manual.

Once all the above has been checked as right as the mail, its time to check for spark. Remove the high tension lead from the center of the dist cap and place it so the exposed electrode has a roughly 3/8th inch air gap to chassis ground. Have a helper crank the starter while you watch for a spark to jump the gap. It should be ye-orange in color. If that goes well, replace the wire to the dist cap and unhook any one of the six plug wires from a spark plug. Do the gap to ground crank spark check again. If that checks good, remove each of your spark plugs one at a time, leaving the others hooked up to avoid mixing. Inspect the electrodes for fouling, damage or excess wear. If they look good, check that the electrode gap is to spec (manual yet again) and install. Lather, rinse, repeat for the remainder. Now, if you have air, fuel and spark combining in the combustion chamber in the proper amount at the proper time, the engine should show signs of life in quick fashion.

You obviously have a lot to sort through. Bringing a long dead dog back to life isn't usually a quick stroll through the park. It is often a painstaking, methodical process.
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Old 07-31-2016, 10:22 AM   #3
Kneadabagel
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Thumbs up Re: C120 won't start

Thanks. Will chew on that. Lots of good info.
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Old 08-02-2016, 11:32 AM   #4
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Default Re: C120 won't start

How do I determine what kind of carb it is? Where is number located?
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Old 08-02-2016, 11:41 AM   #5
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Default Re: C120 won't start

Carb model number & IH part number are typically stamped into the airhorn.
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Old 08-03-2016, 10:33 AM   #6
Kneadabagel
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Default Re: C120 won't start

The only numbers I could find are 1238 I. And under it 8708 r 91. Couldn't find those numbers on parts page.
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Old 08-03-2016, 11:20 AM   #7
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Default Re: C120 won't start

Quote:
Originally Posted by kneadabagel View Post
the only numbers I could find are 1238 I. And under it 8708 r 91. Couldn't find those numbers on parts page.
What "parts page" are you referring to?

Most likely a Holley, one barrel, model 1904.

Can you post photos of your carb, etc.?
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Old 08-03-2016, 12:18 PM   #8
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clip Re: C120 won't start

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Old 08-10-2016, 04:28 AM   #9
1975IH200
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Default Re: C120 won't start

Well, I thought it went without saying but I guess not.
So,........your photo is about useless.

A side view would be better. Maybe a front view too.

Also feedback from you in the form of responses to our questions and suggestions would be helpful.

Did you do anything and get any results?

We don't know.......................

You could also spend some time in the carb tech forum under the Holley 19xx sticky thread.
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Old 08-10-2016, 12:47 PM   #10
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Default Re: C120 won't start

Filed the points and the engine started. Thank you for the input. Rebuilt carberator now off to brakes and clutch. Both are to the floor.
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