So today on the way home the truck started to dead miss on cyl 1. Checked the plug. Replaced the wire. Problem solved. But I noticed that the cyl 1 plug was at an angle towards the firewall? Is that normal? I've done a plug hole repair on a 4.6 before and as I recall the plugs are straight in the holes? Do some cylinders have angle plugs and others straight?

 

Lol nope...all generally the same angle. Looks like you might be in the mood for another plug hole repair...not to worry though...they're easy with the cal van kit. That is, if you're not afraid of putting a little metal in your combustion chamber, eh?

All seriousness though, #1 should be fairly easy...I had to do #4. Then I did all the rest just to make sure there were no problems in future.

 

I'm gonna leave it until it's an issue haha. The plug tightens up good and the threads look okay.

 

​​​​​​As long as it isn't throwing a code or acting funny, why worry?

 

Exactly. It's a taper seal and tight is tight lol. It's interesting that it's at an angle, but it's possible that it's already been repaired and the hole was tapped incorrectly? Who knows. I read one how-to about spark plugs in these engines that states that some of the plugs aren't perfectly straight in the hole. So maybe it's not that abnormal.

 

Actually it's that taper that is one of the main causes of the problem. The heads were drilled with that taper because it was more forgiving for the factory machining process and allowed units to be produced faster than perfectly cylindrical boring would allow.

Unfortunately, with only four threads and a taper, it made it far more likely that misaligned and under/overtorqued plugs would cause eventual erosion of the threads and leaking/blowout.

And to what you read, yes there was a lot more human involvement in the drilling process than there is on production parts today, so it could easily be likely that Jethro had a bad day at work. Not saying computer controlled machining is better, because it can screw up just as much if not calibrated, but you saw a few more things slip past qc back then.

 

I thought the whole 4 thread issue wasn't an issue on the old 4.6 2v. Aren't these engines 8 thread?

 

My #4 cylinder after tapping for the cal van threaded insert. Believe it only had half as many threads beforehand, as the bore is used to drill out a larger hole before the tap can cut the new threads. If you put a plug in before this drilling, I believe you can feel the transition for the old shelf.

In essence, you're obliterating the old shelf for the new one that the insert seats up against.

4.6l 2v.