4.0 head swap update

[crazyguy]

just installed the 4.0 HO head on my 4.2 shortblock tonight. pushrods are in and rockers tourqed down now as well.

tried turning it over with a 3/8 ratchet on the harmonic balancer bolt and it definetly sealed well :o) gotta trim the carb intake to fit with the '92 factory header and then im done other than installing accesories. engine goes in easter weekend.

forgot to take pics of the head after I JB welded the neccasary coolant passages so can't post that but theres enough of those pics on the net. i'll try and get some pics of what im doing to the intake so it fits with the header.

[Mud Jester]

I was thinking about try this... did you rebuild the bottom end first.. if not, how many KM's you got on it..
I got a 87' YJ, 150,000 km's, so i don't know if it's really worth it or not... I also know where i can get a cheap 4.0 head. Exhaust header and intake... But i am not sure what kinda shape it's in... :soso Could you keep me posted on how it goes... What have you been looking at for cost too...?

[crazyguy]

I rebuilt the bottum end. its a stock bottum end, .040 over pistons, stock cam. head is a '92 4.0 HO. was about $500 to have the block hot tanked, magnafluxed, bored, new pistons plus install on rods, cam bearings plus install, $250 to have the crank re-ground including the cost of new main and rod bearings to match. id have to fiund the reciepts but I believe the oil pump, pistons rings, and complete gasket set for the 4.2 came to about $150, I paid $200 for a complete '92 4.0 HO. was another $50 for the head gasket, valve cover gasket, intake/exhaust gasket, and valve seals for the 4.0 head. you have to use the 4.0 head gasket for the swap. in hind site I did not need the complete gasket set for the 4.2 but it was only $50 for the entire set so I didn't lose anything(would have been more for the seperate gaskets I needed for the 4.2).

I spent a few evenings filling the coolant passege holes that need to be filled by layering them up untill it sealed as I did not have anything I could stuff into the passages thats would disolve with coolant and I added each layer while the previos was still tacky. after all the JB weld was on and failry dry but not completly set I took a razor blad and sliced the excess then let it completly harden before taking some 120 grit and slightly recessing the JB weld. I spent a great deal of time hand grinding the valves myself in order to save some coin.

as I am currently staying with a carburated induction I have to modify the stock 4.2 carbed intake to fit in with the '92 4.0 HO factory head, need about 1/4 inch removed from the side in order to fit properly, the carbed intake will not locate properly if you put it on the locating dowels on the 4.0 head, instead you have to rest it on top of the locating dowels and locate the intake carefully.

with 150km on your motor I would not recomend doing this as you are asking for trouble. it is not recemended on a higher millage motor to be rebuilding one end of a motor without doing the other end.

[dooboy]

that seems like a lot of work when you can get a complete 4.0l HO for $250 from the for sale section.

[crazyguy]

I got a complete 4.0 for $200. and it was something to do, basically just another hobby for me. the big thing though is I wanted a fresh engine that I knew how it was put together(I did it and I know I did it right), I wanted a bit more power, and I wanted something I could bolt in on a weekend and be driving again by monday without any major work. but hey if you could have found me a complete freshly rebuilt 4.0 including wiring harness, computer and a CPS relocation setup for $250 I would have snapped it up and installed it :rolleyes:

[Y-James]

great info crazyguy. keep us posted and get some pix:mullet

[crazyguy]

ooops, as much as I tell myself to take pics I never do. anywho engine is in and went for the break in drive tonight. feels great, see how it goes as it breaks in and I tune the carb a bit as well as figure out the best timing. took my awhile to find the right length of pushrods, the rods I originally used came out of the '76 block im using and were to short causing one hell of a racket, the pushrods im using now are from a mid 80's 258.

exhaust is currently a bit mickymoused to make it work, goes form 2 and 1/4 at the manifold to 2inch about a foot away so its kinda restricted, at some point i'll take it in and have a new exhaust thats 2 and 1/4 the entire length. well off to go do some more driving :)