AMC 258 vs. AMC 304

[rwellman]

1049368

In general, which engine is better? I'm looking for a project CJ7 to buy and am debating which engine is better. The I6 is more common than the V8 and not as rare, but isn't the V8 worth waiting for?



I've also seemed to notice that there are more modifications that can be done to the 258: headers, carbs/fuel injection, etc. Is this true, or have I just not found the right place to go for 304 modifications?



Is there a difference in stock transmissions/axles for the 258 vs. the 304 or are they the same?



Thanks for the help[addsig]

 

[Tug-n-pull]

1049374

Welcome and hope you like it here. You are more than likely to get fifteen post or more and all will tell you why they want or would want the 6 or the 8. the question is what do you want from your jeep after you get it. A daily ride, some trail rideing, serious trail riding and a bit of road travel, or are you going to the extrem with a go anywhere do all get the job done beast?



Once you know what you want to do then you can go from there. I run a 4 banger! The worlds smallest wonder an AMC 150 ci 2.5L hi out put little engin that can and does. Some days I wish I had a six like on a long pull up on the highway, othere times I wish I had a fire breathing V8.



The 4 banger is just fine for me now. If it ever gives up the ghost I will think bigger, but for now am happy with that. So make up your own mind but hear what all have to say. Bigger is good but not always better. Seems folks respect the 304 and it does have a sweet rumble to it! Later Tug[addsig]

 

[1bigmf]

1049376

get the 8 later u will want it ....nothing wrong with all others but if u can have an 8 y not .... they just sound cool and power is great with an 8... u will never say " man ,, my jeep needs more power " or "i'm slow cause these tires are so big"

[addsig]

 

[rwellman]

1049380

This is strictly going to be a fun vehicle for wheeling, not a daily driver. But I will most likely be taking it on the freeway to get to my wheeling desitination quite often.



So if I were to buy a 258 (because of availability) and convert to a 304 later, would I have to swap out different axles, transmission, t/c? Or does the 258 and the 304 come stock with the same equipment (assuming it was stock in these areas)?[addsig]

 

[RayOvac]

1049384

Depending on the year of the jeep...the swap could be very simple or very complicated. Say for instance its an older (pre 1980 or so) jeep. These jeeps generally have much stronger transmissions that can and will hold up to the power of a V8. Most of these will have either a T18, T98, or T150...autos came with the TH400. All are very strong transmissions and will hold out under V8 power very well. Once the jeeps came into the 80's the transmissions just went to pot...pitiful examples include the T5, SR4, and AX4&5...try to get one with a T176 manual and the best auto in the later CJ's would have to be the TF727 as far as hooking up to a V8. Mainly a 304 will pretty much bolt directly up to any transmission used by the 258...transmission durability is what you would worry about. As far as the other parts you should be okay.[addsig]

 

[far_right]

1049387

i think the two engines produce the roughly the same numbers w/ the 304 comin in a little higher.....the 285 produces its torque at an incredably (sp) low rpm around 1800... and i would think the 258 is lighter....and there are only 3 years you can get a 304 and a d300 t-case, and the t-176 is plenty strong, though it doesnt have the increadbly low first of a t-18....[addsig]

 

[jeepmastr1]

1049397

i had a 84 cj7 with 258 and after slight mods lift bigger tires i swapped out for v8. it ran fine had plenty of power and by swapping motor ran with lower rpms on hiway. missed gas milelage but cant have cake and eat it too. the jeep i have now runs 258 and i slight modified it./tires/lift... once again am swapping for ford v8. my motor in 3rd gear runs medium rpms,but with v8 will run at less rpms. could swap out gears and differentials,but dont want to tear down that far.i also find that the carb on 304 ran very good even on steep inclines. just replace accelerator pump if carb has hi miles. simple to do and noticeable.[addsig]

 

[AFholmz]

1049435

Im fond of the straight six, love the low end power, but the V8

does produce more hp's and ft/lbs of torque. If the weight of

the engines is of any concern, the V8 weighs less. like 400lbs.

the six weighs over 500.[addsig]