I have a 63 F100 4X4 with a 400 transplanted into it. It seems to be running funny lately. It will run fine for a few minutes then it seems to skip a beat and almost die, and then it runs fine for a little while. Im going to check the plug clearances tomorrow.

And also, i've been having troubles starting it. Usually the 10 pumps of the gas and it starts right up, but now that doesnt work, and I can rarely get it running, even when I prime it....so I think that means fuel isn't the problem. Any ideas???
And its running through starters like crazy (Taking teeth off starter, ring gear is fine). I will post a video, and pics of the starter in a minute.

 

The running issues sound spastic enough to me to be electrical. When it comes to fuel, you're either getting it, or you're not, so that doesn't sound like the problem. I don't think plug gaps are going to be the culprit either, as they can't change magically....if the truck runs fine, and then doesn't, the plugs have nothing to do with it.

If I had to throw a guess out there, I'd say that your distributor or ignition might be worthy of a look. Another possibility is voltage regulator, but those usually crap out all at once. I've seen distributors go bad before they quit, so it's possible. The ignition (if original to the 400), while generally quite reliable, can always develop issues, so who knows? Anyway, those are the areas I'd begin with as you have air and fuel, and spark is the question mark.

As for the starter, if it's eating teeth, that tells me that it's not shimmed correctly. One thing that some guys forget when putting a motor in, is that aluminum dust shield that goes between the block and the bellhousing. That difference in thickness, while not necessarily changing how the engine or transmission run, can potentially play havoc on a starter. When I was putting the engine into Buford, I had to pull it back out because I forgot that stupid shield myself. Luckily I caught the mistake the same day (just didn't help my mood). Anyway, that'd be my guess on the starter....wrong position due to improper shim is making it eat teeth.

Just my $0.02

 

Here's a crappy video. Sorry, camera suddenly wouldn't load, so I took a video of the video .

Seems like the starter has died. Had about 20 spins on it.

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The running condition you describe also sounds like a badly worn and loose cam chain. With all the slack in the chain, the engine will phase through many degrees of timing, and go from running good to barely running at idle. To check, pull your distributor cap and rotate the engine one way and then reverse rotation. Note how many degrees of crank rotation you get before the rotor moves when you reverse directions. As per previous post, you should check the distributor also.

 

Anybody know what the clearance on the plugs should be?

 

.042-.046

https://www.ford-trucks.com/forums/6...-plug-gap.html