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I would not use a nylock nut in this situation. I have had the nylon melt from heat and the nut back completely out several times on 2 different projects.
Once I lost an exhaust on a go-cart as the pipe was too hot for the nylon.
On the other one, I shot an arrow into the ceiling (luckily) when my hand held string release blew up. We had trimmed the 1/4-20 threaded rod down to size with a cut off tool and ruined the nylon. It looked fine but two weeks later it created a deadly situation.
What temps will this head be running at and is there any danger of eating the nut into the sump if the nylon melts?

What he said

_________________
Wade Williams
Master Ferrari Tech
Restoration Tech
Engine Machinist
Fabricator
Racecar Driver

You could put a nice Chevy in it.

Just interested, what is it in and what are the engine specs?

_________________
Wade Williams
Master Ferrari Tech
Restoration Tech
Engine Machinist
Fabricator
Racecar Driver

1965 Shelby GT350 racecar with the 289 hi po motor.

Talked with our (new and trusted) engine guy in CT and he thinks we should be fine with studs and don't follow the Ford recomended torque sequence for the intake manifold. The specs say to torque those for bolts first. Our engine guy says do those last and we should be fine. Maybe go a couple ft pounds light on the torque as well. The heads do not seem to be angle milled.

I'm still curious if anyone has experience with welding cast iron and what your thoughts and experiences with it would be?

I have cast iron welding exp but In this case its going to be a big job. You would have to mill the break flat(at an angle) find a piece of similar nodular iron and fettle it into shape, bevel all parts back at edges, preheat the lot, weld, control cool, jig on a mill, rebore the hole next size up, flycut new boss if over flange surface(skim), tap, helicoil down to original size, pray head has not twisted with pre heat(it should not).
As mentioned, stud with nut underneath - loctite on nut and tighten against lower surface - loctite stud too into head.
Take pictures before and after and put on file or keep. (or_not )

Brian,

Any issues with the area being bathed in oil for 50 years since cast is somewhat porus or would the preheat take care of it? Would TIG be the best? Any thoughts on brazing with hard brass like the english use on racecar frames?
I've done a fair bit of TIG welding but haven't messed with any critical cast iron parts I really cared about.

This area is on the intake side of the head so I wouldn't expect it to get any hotter than the max oil temp. Maybe 250F?

Not sure I need the nut at all. Like some have said just one more thing to fall into the lifter galley. Probably doesn't add any strength.

Stick welding with nickle rod is the most common way to deal with cast iron and I've had some luck with it.

Brazing usually works but iron doesn't usially wet out very well, at least not for me

The pre-heat to glowing, weld, controlled cool Brian spoke of is best but I've only done it on small parts.

what I've had the best luck with is mig welding it. You do a small bead then walk away until it's cool, then another small bead....and eventually it's done. I did some pretty long cranks in boat exhaust manifolds this way with good luck.

another option for your heads might be to weld or bolt a plate to the side then drill and tap the hole....but I really believe a stud with a not on the bottom will fix your problem and you won't need to give it another thought.

What heads are these?

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Todd