Possibly, depending on where the crack was. I had a crack in the rotor on my 3.0L several years ago that would cause hesitation/stumbling/near-stalling when trying to accelerate from a stop, but the engine idled fine. Turns out the crack allowed a short to ground. Perhaps you have a similar issue with your distributor cap? If you run it while dark, you may be able to see it arcing...

Eric W.

So I just got around to taking a look at things. Here is what I've found so far.

Looks like one of the jet valves is way out of adjustment compared to the others:



Cap and rotor look alright:





Here are the plugs, right side is the front of the engine and the 2nd from the right has oil on it:



What do you guys think?

The jet valve that is out of adjustment, that one is stuck open allowing combustion to blow back into the carb.
Pull that jet valve out and either replace it of fix it and you should be set.

The 2nd from the left looks worse - it's sooted badly. Check the jet valve adjustment, check cylinder compression, check for sticking valves and check the plug wire (assuming the cap is ok).

Frank

Ditto both of the above (Frank and Charlie).

Look closely at the cap insides for signs of tracking, like a pencil mark from the inside post on the 9 and 3 o'clock posts to the center. I see something, but it may just be the casting seam.

Most likely is the jet valve per Charlie's post above. A jet valve eliminator kit is cheap, and good insurance, and will not affect the engine normal running at all. I hate jet valves...

You can't see in the pictures, but 3 of the JV's have less than 1/8" of threads from the adjuster sticking out where the 2nd from the front is a good 3/16". That is the oil covered plug apparently. That jet valve was all the way out because of the position of the cam and not touching the adjuster at all.

Might be able to see the difference better in this one:



I'm not necessarily against removing them, but it would be less work if I can just adjust them and go I am hoping.

I'll probably throw a new cap on with new plugs and go from there, the orange wires you see are actually replacements from the last ignition issue I had.

Anyone have the JV specs handy? Maybe just adjust that one to what the others are and try that first?

Hang on, what do you mean by fix? Would the fact that the adjuster is off mean its bad? Should I first try readjusting?

You adjust the JV's to .010", but why bother? They are an accident waiting to happen. It's not a lot of work to put in the JV eliminators, which are a bolt looking thing with an oring seal. You take off the cam sprocket and let the sprocket rest on the little metal shelf just below it. Then remove the rocker arm shaft cap bolts, loosening each a little at a time to avoid having valve spring pressure bend the shafts, until the spring load is off. Use cut off rubber glove fingers to hold the hydraulic lash adjusters in the rocker arms. Lift off the rocker shafts and rockers, leaving the 4 end bolts in the caps to retain all the assemblies on the shafts. Remove the jet valves from above, unscrewing with a deep well socket, making sure all the parts come out with the JV, especially the head and valve stem. Install the JV eliminators, and reinstall is the reverse of the take apart, except use a smear of rtv on the mating surface of the top and bottom halves of the rear cam bearing cap, and reseal the circular cam bore plug to the head and rear cam bearing cap. By the time you rotate the engine, and set a JV, and rotate the motor again, and adjust another one, you have the problem solved by eliminating the damn jv's altogether.

So Eddy, where do you get the JV Eliminator kit from? I'm about to do the timing chain, may as well take care of that while I'm in there.

Try any machine shop, some auto parts houses, or Engine Machine Service, whose owner is on here some and on the starquest boards a lot, Randy, I think his name is...

A google will turn up multiple sources. Stay away from Racetep...