I am looking at these Apache cylinder heads, left and right, and they are side specific.
What I have figured out (if I am correct) is;
-Exhaust bolt pattern is different, there is boss material there to drill and tap to make them both the same.
-the right head exhaust flange has an added hole as well as a threaded hole. This I have no idea as I don't have an engine to look at. Does anybody know what they are for? Lower head left side.


-Next to the intake ports are cut-outs. I take it that one is for oil filling, what is the other for?


To make these heads work for either side the exhaust bosses would need to be drilled and tapped.

Also each head would need to be drilled for oil return at the back of the head. It seems like there is enough material there to do this.


Any thoughts, comments or answers would be appreciated.

1. EGR passage
2. Crank case ventilation

Crankcase ventilation, makes sense.
EGR, this hole is not drilled through to anything. But I believe you as to it's location as well as some heads that I was looking at online asked for EGR or Non-EGR.
Obviously these ones are Non-EGR heads. Thanks.

What about the drilling of the oil return to make these heads work on either side of the engine.
Have you done it?

Also is there anything else that makes these side specific that I may have missed?

I have not attempted to make the heads work on either side. I have only built a couple of these Gen 3 engines and "still learning" is an understatement!! I am always watching the Gen 3 topics and learning as much as I can and willing to share what little I know about them.

Thanks Chapper,
your sharing has learned me a bit.

I watch these gen III threads also because I plan on going Gen III in the future, sooner if I blow up this magnum motor

Any particular reason you want to use the same head L/R (ported, better valves/springs, etc)?

If it came down to it, I'd be tempted to keep any parts off (if they are better than stock) of one of the heads and sell it and put those funds into the correct correct head, or sell the whole head and buy the correct head for the side instead of investing all the time and effort (and getting it machined, threaded correctly, etc) into finding out if the other head could possibly be converted to use on the other side.

No particular reason.
Just if down the road if I needed the heads to fit either side I could do it if need be.
I am learning as I go along.