4.0 Head on a 258

Dallas Lemon

Why must a 4.0 head gasket be used for the swap of a 4.0 head onto a 258? Why do I ask? Because we did that conversion on my son's CJ, and it uses a quart of oil every 100 miles. No smoke, no leaks. I am baffled. Especially when it used no oil with the stock head. We did use a 258 head gasket. But, I cannot see why that would cause excessive oil consumption. It runs very well. #-o

jeepsr4ever

I believe the ports for the coolant are different...maybe oil as well

pyagid

this is the best article i have seen on the swap, it has pictures that shows the differences.

http://monsterslayer.com/jeep/40Head/40Head.htm

Its wierd that you say it is basically just loosing the oil, with no signs of where it is going

-Paul

CJim7

The only difference between the 4.2 head and the 4.0 head are the water jackets as far as the swap is concerned. The swap doesnt affect oil transfer through the valve train whatsoever.

Dallas Lemon

CJim7 wrote
The only difference between the 4.2 head and the 4.0 head are the water jackets as far as the swap is concerned. The swap doesnt affect oil transfer through the valve train whatsoever.

Thanks. I couldn't see how it would affect anything from the oil side, either. I think it's time to quit screwing around with this thing and build a stroker!

oldscout401

Sorry I can't help with the oil burning problem, But this post caught my attension because I didn't know a 4L head would work on a 258. I have two CJs with 401 engines and fuel costs are killer. I've got an old 76 258 so in theory one could put a 91 4L head on it with the factory fuel injection and possibly get 180 HP with the torqe of the old 6 and boost the mpg to 19 0r 20. Anyone done this?