Helicoil in 4.2 258 head

[fcb212003]

I bought a new valve cover and went to put it on the engine, but noticed the bolts that came with the valve cover were too big. Upon closer look, I noticed helicoils in the bolt holes on the head. This engine had been rebuilt twice over the years and I don’t know if these helicoils are stock or not. Can I remove them? Will it damage the engine? I just wanted to doublecheck with you guys before I did anything. These are not the holes that I will have to drill and tap. These are the pre threaded holes.

 

[shum8]

I bought a new valve cover and went to put it on the engine, but noticed the bolts that came with the valve cover were too big. Upon closer look, I noticed helicoils in the bolt holes on the head. This engine had been rebuilt twice over the years and I don’t know if these helicoils are stock or not. Can I remove them? Will it damage the engine? I just wanted to doublecheck with you guys before I did anything. These are not the holes that I will have to drill and tap. These are the pre threaded holes.

Never tried to remove a heli-coil...... that might be a pain. And if they retapped the old threads to accept the heli-coils then the stock bolts won't fit. Any chance you can just use bolts sized to the heli-coils?

 

[CJ RIGGS]

You need to start by asking, are the new bolts the stock size.

typically a hole is heli-coiled to repair threads to the original size. Which means stock bolt would work.

It almost sounds like the threads were wallowed out and someone heli-coiled them one size down. That's why your bolts are too large.

You have three choices:
1. pull out the heli-coil and check the threads (see what codition they are in.

2. Live with the fact that they're a smaller size or

3. Drill and heli-coil them correctly to receive stock bolts.

 

[shum8]

I think I’d go with option 2 since it’s just a valve cover......


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[CJ RIGGS]

I would have to agree with shum8. I did forgot to mention, when drilling out for the correct thread, there may not be enough meat or wall to accommodate. I'll look at mine tonight to see what there is.

 

[CJ RIGGS]

This is of a 4.0L and a bit different but I noticed that several of the holes up front near the water pump are into the water jacket.
The good news is there is plenty of room if you needed to resize later.

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[Lumpy Grits]

HC is not OEM on the AMC 258 i6 / 4.2l .
Get the smaller bolts.
OLG

 

[fcb212003]

Sounds like going with smaller bolts is the way to go. I was not sure if that would be an issue or not. I know oil used to leak bad out of the old valve cover, but I think that was mostly due to the old plastic cover.

I appreciate it guys!

 

[Lumpy Grits]

Still run the plastic on mine-
Make sure you have the correct PCV valve in place.
LG

 

[JimsCJ5]

Barrel inserts are a better option than helicoils. You can get them from McMaster Carr. I've repaired those same holes on mine where the PO had used helicoils and they had failed.