I recently picked up an 89 4.0 that I plan to use the block as the base for my stroker project. The block is in great shape but I just noticed this hole above the camshaft, behind where the timing cover would be. I found a few threads where people have noticed a similar hole with conflicting responses. Some people say they have the same hole and others say they don't. Is this normal? If so I'm guessing to oil the timing chain/gear? As you can see it's a jagged weird shaped hole, does not look like a factory hole...

 

No one?

 

Looking at this thread the shape of the hole looks almost exactly the same to me. http://www.jeepforum.com/forum/f19/h...cover-1227936/

 

You're good to go. They all have that hole, even though it looks like a crappy casting error. LOL.

 

Thanks Cruiser. I think my buddy Renegade90 got it right.

Guess AMC figured ammo was cheaper than drill bits. "hmmmm should we machine a nice hole in it?"
"hell bubba's got his old 30.06"
"works for me"

 

"Here, you hold it right here".

 

What the heck is that for? What's amazing is that they all seem to look different. Must be the personal touch of the dude with a crow bar at the end of the casting line....

 

These blocks are solid cast iron... Depending on what year, reinforced. Be hard for someone to put that there with a crowbar. Or even a firearm. I vote; Trademark.

 

My guess is to oil the timing gear and chain.

 

Yep.

 

X2. As oil runs back down from the head into the passages, some is diverted to the timing gears and chain.