Question on 258 to 304 swap

"Greg" > wrote in message
news:aSxFd.68064$8l.32156@pd7tw1no...
> Next couple months I will be getting a remaned engine to replace my 258,
> ( 81 CJ7 ) as I wont be sending the core back, ( $150.00 core charge, I
> think shipping will be 1/2 that ) is there any difference in the 258 to
> 304 as far as the parts I have to swap over on a remanned long block, do
> all swap, some swap, or not worth the trouble for a few more horses?

Other than the obvious distributor and wires, intake and exhaust manifolds,
carb, front exhaust, oil pan, valve covers, and probably the radiator?

I just did this and chose to go with a 258 for exactly this reason. Swap
needed almost nothing.

If I was going to bite the bullet and do a V8, I'd do a Chevy small block.
Its a bigger job, you'd probably need a new transmission, but you have
an engine that still has parts available. Plus you can get one built to
whatever HP/specs you want.

Almost did this but when I thought about it the 258 was enough, I drive the
jeep easy. I have gone to an HEI distributor and Weber carb, they help a
bit.

Thanks, like you I don't need the extra power, just figured if everything
was just a direct swap then what the hell.

"Charlie Dellacona" > wrote in message
...
> "Greg" > wrote in message
> news:aSxFd.68064$8l.32156@pd7tw1no...
>> Next couple months I will be getting a remaned engine to replace my 258,
>> ( 81 CJ7 ) as I wont be sending the core back, ( $150.00 core charge, I
>> think shipping will be 1/2 that ) is there any difference in the 258 to
>> 304 as far as the parts I have to swap over on a remanned long block, do
>> all swap, some swap, or not worth the trouble for a few more horses?
>
> Other than the obvious distributor and wires, intake and exhaust
> manifolds,
> carb, front exhaust, oil pan, valve covers, and probably the radiator?
>
> I just did this and chose to go with a 258 for exactly this reason. Swap
> needed almost nothing.
>
> If I was going to bite the bullet and do a V8, I'd do a Chevy small block.
> Its a bigger job, you'd probably need a new transmission, but you have
> an engine that still has parts available. Plus you can get one built to
> whatever HP/specs you want.
>
> Almost did this but when I thought about it the 258 was enough, I drive
> the
> jeep easy. I have gone to an HEI distributor and Weber carb, they help a
> bit.
>
>

I know the engine mounts are different. The mount pad also go reverse
with the torque hooks on the other side.

I would imagine the rad is different, the 258 rad is barely enough for
the 6.

I too would have gone 350 if V8, but stayed with the 258. Once the
computer is gone out of the ignition they go pretty good.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail
88 Cherokee 235 BFG AT's

Greg wrote:
>
> Thanks, like you I don't need the extra power, just figured if everything
> was just a direct swap then what the hell.
>
> "Charlie Dellacona" > wrote in message
> ...
> > "Greg" > wrote in message
> > news:aSxFd.68064$8l.32156@pd7tw1no...
> >> Next couple months I will be getting a remaned engine to replace my 258,
> >> ( 81 CJ7 ) as I wont be sending the core back, ( $150.00 core charge, I
> >> think shipping will be 1/2 that ) is there any difference in the 258 to
> >> 304 as far as the parts I have to swap over on a remanned long block, do
> >> all swap, some swap, or not worth the trouble for a few more horses?
> >
> > Other than the obvious distributor and wires, intake and exhaust
> > manifolds,
> > carb, front exhaust, oil pan, valve covers, and probably the radiator?
> >
> > I just did this and chose to go with a 258 for exactly this reason. Swap
> > needed almost nothing.
> >
> > If I was going to bite the bullet and do a V8, I'd do a Chevy small block.
> > Its a bigger job, you'd probably need a new transmission, but you have
> > an engine that still has parts available. Plus you can get one built to
> > whatever HP/specs you want.
> >
> > Almost did this but when I thought about it the 258 was enough, I drive
> > the
> > jeep easy. I have gone to an HEI distributor and Weber carb, they help a
> > bit.
> >
> >

What's different?... everything!

Since you don know what all that entails. I assume it's not you personally
that would be doing either type of swap.

My 258 does just fine... when it goes, I will rebuild it.

You might check prices at your local Advance... then you could take
advantage of the core return.
--
JimG
80' CJ-7 258 CID, HEI
4.56 Gears, Lock-Right F&R
35" BFG MT on 15x10 Centerlines
D44 Rear, D30 Front. SOA
Dana 300 w/4:1 & Currie twin sticks
Warn X8000i w/ dual batteries

00' TJ Sport 4.0L, 5sp
4.56 Gears, TrueTrac rear
33" BFG AT on 15x8 Eagle Alloys
D35 Rear, D30 Front. 3" Suspension Lift

"Greg" wrote in message ...
> Next couple months I will be getting a remaned engine to replace my 258,
> ( 81 CJ7 ) as I wont be sending the core back, ( $150.00 core charge, I
> think shipping will be 1/2 that ) is there any difference in the 258 to
304
> as far as the parts I have to swap over on a remanned long block, do all
> swap, some swap, or not worth the trouble for a few more horses?
>
>

Well, one block is four cylinders long, and the other is 6, not to mention
the different sizes of the respective cylinders.

Nothing will swap, except perhaps the alternator and the power steering
pump.





"Greg" > wrote in message
news:aSxFd.68064$8l.32156@pd7tw1no...
> Next couple months I will be getting a remaned engine to replace my 258,
> ( 81 CJ7 ) as I wont be sending the core back, ( $150.00 core charge, I
> think shipping will be 1/2 that ) is there any difference in the 258 to
> 304 as far as the parts I have to swap over on a remanned long block, do
> all swap, some swap, or not worth the trouble for a few more horses?
>

I did the 258 to 304 swap and I can help you with details if needed. It's
not easy, but it's not real hard either. For starters you'd need new motor
mounts (block and frame side), radiator, and probably a new transmission if
you have the t4 or t5. Plus the other stuff already mentioned.

If I ever do it again I will go big (401) or go with chevy power like the
other said.

--
___________________
HomeBrewer
http://85cj7.blogspot.com/
http://85cj7.webhop.net/
http://funfacts.webhop.org/

Chevy, they're a dime a dozen, and with the help of
http://www.advanceadapters.com/ or http://www.novak-adapt.com/ will bolt
straight in.
God Bless America, ßill O|||||||O
http://www.billhughes.com/

HomeBrewer wrote:
>
> I did the 258 to 304 swap and I can help you with details if needed. It's
> not easy, but it's not real hard either. For starters you'd need new motor
> mounts (block and frame side), radiator, and probably a new transmission if
> you have the t4 or t5. Plus the other stuff already mentioned.
>
> If I ever do it again I will go big (401) or go with chevy power like the
> other said.
>
> --
> ___________________
> HomeBrewer
> http://85cj7.blogspot.com/
> http://85cj7.webhop.net/
> http://funfacts.webhop.org/

Greg wrote:
> Next couple months I will be getting a remaned engine to replace my
258,
> ( 81 CJ7 ) as I wont be sending the core back, ( $150.00 core charge,
I
> think shipping will be 1/2 that ) is there any difference in the 258
to 304
> as far as the parts I have to swap over on a remanned long block, do
all
> swap, some swap, or not worth the trouble for a few more horses?

Greg,

I've done this swap twice (259 to 304). I've heard all the arguments
about the 350. I wanted to stay in the "AMC Family" though. Another
advantage is not having to swap the tranny or mess wtih adapotrs.
Makes it easier for those of us less skilled mechanics. However if I
did this a third time I would go with a 360 or 401. If you're gonna
go, go BIG.

The swap is not really that hard. I would rceommend that you get
several different manuals and study (not just read) up on the
procedures. The first time I did this I had a really basic set of
tools and was able to pull it off.

--Most deffinatly have to swap the radiator. You'll also need new
hoses.

--Carb and manifold are different. The fuel line comes into the engine
compartment on the "wrong side" after the swap so you have to reroute
it.

--Power steering pump is the same, but the brackets are different and
HARD TO FIND.

--You can get away with the same alternator, but again different
brackets.

--Need all new motormounts

--Wiring is a little different. Make sure your manuals have a good
schematic of both the current engine and the one you are swaping in
(the year of manufacture can make a difference here).

--Distributor is different.

--Exhaust manifolds are different.

Both the 304s I put in were pre ECM so I can't speak for that part of
the swap, I just by passed it. On the second one I used a complete MSD
system.

And of course don't forget about EMISSIONS!! This can really bite you
in the a** depending on where you live. I just left CA (thank God) but
they got a lot of money out of me to pass my Jeep after the
conversions.

Hope this helps

Erik

Well all opinions talked me into just redoing mine, thanks for all the
advise.

"Greg" > wrote in message
news:v6BFd.68589$Xk.42701@pd7tw3no...
> Thanks, like you I don't need the extra power, just figured if everything
> was just a direct swap then what the hell.
>
> "Charlie Dellacona" > wrote in message
> ...
>> "Greg" > wrote in message
>> news:aSxFd.68064$8l.32156@pd7tw1no...
>>> Next couple months I will be getting a remaned engine to replace my
>>> 258, ( 81 CJ7 ) as I wont be sending the core back, ( $150.00 core
>>> charge, I think shipping will be 1/2 that ) is there any difference in
>>> the 258 to 304 as far as the parts I have to swap over on a remanned
>>> long block, do all swap, some swap, or not worth the trouble for a few
>>> more horses?
>>
>> Other than the obvious distributor and wires, intake and exhaust
>> manifolds,
>> carb, front exhaust, oil pan, valve covers, and probably the radiator?
>>
>> I just did this and chose to go with a 258 for exactly this reason. Swap
>> needed almost nothing.
>>
>> If I was going to bite the bullet and do a V8, I'd do a Chevy small
>> block.
>> Its a bigger job, you'd probably need a new transmission, but you have
>> an engine that still has parts available. Plus you can get one built to
>> whatever HP/specs you want.
>>
>> Almost did this but when I thought about it the 258 was enough, I drive
>> the
>> jeep easy. I have gone to an HEI distributor and Weber carb, they help a
>> bit.
>>
>>
>
>

Hum, tempting, freind just bought a 2nd cherokee for parts, 360 in both.

"attnews" <john .n. > wrote in message
...
> amc's 304. 360. amd 401 are all the same block....if you want horsies...
> "Greg" > wrote in message
> news:aSxFd.68064$8l.32156@pd7tw1no...
>> Next couple months I will be getting a remaned engine to replace my
>> 258,
>> ( 81 CJ7 ) as I wont be sending the core back, ( $150.00 core charge, I
>> think shipping will be 1/2 that ) is there any difference in the 258 to
> 304
>> as far as the parts I have to swap over on a remanned long block, do all
>> swap, some swap, or not worth the trouble for a few more horses?
>>
>>
>
>