Jeep YJ 4.2 Engine 4.0 Cylinder Head Swap 

Awesome video as always

Great video. I would like to know answers to the questions people have asked

Nice video! Thanks for sharing. I’m going to rebuild my 258 with a 4.0 head and carb setup until I can get the Holley sniper efi. How do you like it so far? I’m guessing mpg is probably a little better with a better flowing head

good job brother, a question that would give you more strength?, leave the "intake manifold" of 258, or place the "intake manifold" of 242 (with the holes sealed where the injectors go)

What intake did you use? I ordered that Edelbrock head but I’m still waiting for it to arrive.

Been thinking about doing this on my 4.2, the process looks pretty straightforward from y'alls video. But on another note, I spotted about 30 pounds of crack at 14:22 in this video, y'all don't wanna get busted by the cops for that, lots of jail time 🤪

Did you use a gasket to match the block or the head? If you use a head gasket to match the head, is it still necessary to fill those 12 water holes?

Hello I'm working on doing the same head swap now. I have same head 4.0 casting. 7120 number I believe. Wich head bolts did you use ??? I see the 4.0 head bolts in valve cover area are recessed lower than the 4.2 . Did you use 4.0 head bolts ?

Did you reuse the same rocker arms and push rods off the 4.2 head? Looking to do the same soon

What head gasket and push rods did you use? I’m using a 1980 258 block.

What did you do about the fuel injector ports? 🤔 My '87 YJ most likely needs an overhaul & I still have my '94 4.0 that I can steal the head from but since it's fuel injected, I would have to do something about the ports(it's probably something simple but I'm still curious either way).

Great video. lot of info, Thank you. I am going to do this on my 1977 CJ5. I was wondering about how much horsepower and torque do you think you gained? I know any increase in power in a 4.2 is good. just curious

Tienes algún vídeo de como se carbura ?

FYI if you have the 4.2 Aluminum valve cover it bolts the same

Tienes algun video de como se carbura ?

In what this swap helps in performance?

How are you liking the 4.0 head 2 yrs later?

How many cc on combusyion chamber?

Thanks for your video. 96-99 4.0 heads are 0630 casting #? the AMC forum guys say any 4.0 head flows better than OEM 3.8 or 4.2 heads. However they allege 0630 heads are way to go.

I just got an 89 YJ with the 4.2 and am devouring all related videos and forums at this time. I see this project covered a lot what is the reasoning behind doing this swap?

Not trying to be overly critical, but IMHO the whole point of putting on the 4.0L head is to get the multi-port fuel injection.

Those back valve cover bolts are a bitch on a 4.2

Dat ass