Ignition problems....

[66birdman]

I have a 66 351 and it doesnt seem to like running lately. I replaced the cap, rotor, coil and condenser (points set was unavailable at the time). The parts store also sold me a ceramic ballast resistor, which come to find out isnt even for this truck, so needless to say it didnt get installed. It ran fine for while and all of a sudden it just quit. Once it sits for a few hours it fires right back up and runs for a bit before it dies again unless I keep my foot on the gas. I am assuming it is the resistor wire....sound like a good guess to yall? Or I guess it could be the points I never replaced but I have never heard of them "over heating" which is what this seems to be doing.

[jrmunn]

First, the resistance wire reduces voltage going to coil while the truck is running. This reduces coil voltage going to the points, which helps extend the life of the points. I doubt that your truck would run at all if there was a break in the wire.

I had a similar problem with intermittent running (that developed into more, but that's a long story) with my 1964 GMC 3/4 ton pickup with a 305E engine. The problem turned out to be points, which were also the last thing I changed. I think that there were only two different distributors used on these trucks. You can tell them apart by the rotor. In one case, it is a small rotor that pulls off the top of the distributor shaft (this is what I have). The other has a large, round rotor that is held on by screws. In both cases, these were common distributors and points should be easy to find. (But parts stores are most likely to sell you an adjustable set for the large rotor distributor. The small rotor points are very basic and do not have a gap adjustment screw.) If I am wrong about this, I am sure that someone on this forum will provide a correction.

If it is points, you don't necessarily have an overheating problem. It is just that the size and relative positions of these parts can shift with changing temperature. In my case, the points had burned down into the cap holding them in place. You could check this by looking, but for the small rotor distributor that I am familiar with, resetting the gap can be a real challenge if the points are disturbed or removed.

jrmunn

[tommyduncan]

Originally Posted by 66birdman

It ran fine for while and all of a sudden it just quit. Once it sits for a few hours it fires right back up and runs for a bit before it dies again unless I keep my foot on the gas.

could it be as simple as a stuck float?

I am assuming it is the resistor wire....sound like a good guess to yall?

If you turn the key on but not running see if the wire to the coil is getting 12 volts or 8-9volts. If the resister wire is working it will be 8-9. It will run with 12 volts but you will get pretty good at changing points
I couldn't find a replacement resister wire for mine so I bought the ceramic one(that they say goes to this truck also)and it has been fine.
Another easy way to tell the two distributors apart is the adjustable ones have a trap door in the cap and the mechanical advance weights are just under the rotor, and the rotor screws on.
The other has no trap door, the weights are hidden in the distributor body, and the rotor is small and pushes on.

[66birdman]

oh I forgot a lil piece of info. When it dies it wont even fire with starting fluid so I am 99% certain it is a lack of spark. FYI for other folks NAPA has a resistor wire available for it at 18 bucks. Still havent got around to tinkering too much though. I am also in the progress of building a 66 TBird and it has taken over all my time.

[tommyduncan]

NAPA? The one by me tried to sell me a fuseable link... not the same thing. I would try again but I think an HEI is in my future.

[66birdman]

It could just be that the NAPA I go to has old stock parts. Its a pretty ancient store in the middle of nowhere that caters to farmers n things

[66birdman]

update....I just rewired the entire truck with a painless kit and put in a new ceramic ballast resisitor in the place of the resisitor wire. I also put in new points (if anybody can tell me the right gap for that i would be grateful) I have yet to put power to the system but I have my fingers crossed that its all good now. I guess if its still acting up I will go ahead and replace the distributor....then if that doesnt work I will grab the SBC out of storage and do the swap

[jrmunn]

I have seen a variety of point gap recommendations for the 305 and 351 ci engines. The range seems to be from 0.019 for new points that are then expected to wear down to a setting of 0.016 for what might be called "broken-in" points. I try to set my new points at 0.018, but this is more of a goal than a reality when setting the points on my small rotor distributors because I have never mastered the ability to adjust up or down by loosening the hold-down screw just enough to push the gap a little one way or the other. Instead, it seems that I am always starting over and hoping to end up better. It is critical, of course, to be sure that the points are sitting at the top of one of the high points on the cam when setting the gap. Stopping the engine at this point makes the process even more fun. As soon as I get the time, I am switching to Pertronix ignitors (already purchased) to get away from fooling around with points - where any improvement in performance would just be an added benefit.

jrmunn