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Jeep CJ7 304v8 or 258v6

Jeep CJ7 304v8 or 258v6

bldams123

Jeeper
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Location
Huntsville, Al
Vehicle(s)
1986 CJ-7
Ive done my research and I am very intent on purchasing a CJ7 preferably 80's model. The only thing that remains is which engine type. Im stuck between the AMC 304 v8 or the 2586cyl. I was hoping to hear the pros and cons of both. Right now im leaning towards the 304v8 because of the increased power in the lower rpm range. Any help would be appreciated.
 
Keep leaning to the AMC 304 rigs...that way you can easily put a 360 in it later!
 
All the 6 guys secretly have V8 envy.:drool:
290,AMC 304 ,343,360,390,401 the bigger the better.:cool:
 
No envy here, I passed over a couple 8's before I found my 6.:cool:

It's not like you are ordering from the factory here, The best CJ you can find wins regardless of the motor(stock only) of course.
 
No envy here, I passed over a couple 8's before I found my 6.:cool:

It's not like you are ordering from the factory here, The best CJ you can find wins regardless of the motor(stock only) of course.

I never limit anything to "Stock".:laugh:
 
All the 6 guys secretly have V8 envy.:drool:
290,AMC 304 ,343,360,390,401 the bigger the better.:cool:


All the V8 guys are really over compensating for short comings in their anatomy. :laugh:

Every body has an opinion, I am a AMC 258 i6 / 4.2l fan and Horn has a tattoo that says "there is no replacement for displacement". There isn't a wrong answer they both have good points and bad points. Find a jeep that is in good shape that you are comfortable with. Have you driven an 8 and a 6? If not that would be a good place to start.
If you find a AMC 258 i6 / 4.2l you like we will help you make it run like a fine Swiss watch and if you get an 8 there are guys here that will help make it stand on its hind legs and howl. I have always felt that there are places for massive amounts of horse power, but driving off road is not necessarily one of them IMO. Go find YOUR jeep. :cool:
 
All the V8 guys are really over compensating for short comings in their anatomy. :laugh:

Every body has an opinion, I am a AMC 258 i6 / 4.2l fan and Horn has a tattoo that says "there is no replacement for displacement". There isn't a wrong answer they both have good points and bad points. Find a jeep that is in good shape that you are comfortable with. Have you driven an 8 and a 6? If not that would be a good place to start.
If you find a AMC 258 i6 / 4.2l you like we will help you make it run like a fine Swiss watch and if you get an 8 there are guys here that will help make it stand on its hind legs and howl. I have always felt that there are places for massive amounts of horse power, but driving off road is not necessarily one of them IMO. Go find YOUR jeep. :cool:

How 'bout axle deep on 38" tires in black riverbottom gumbo?;)
 
I may be wrong here but in the 80's I do believe the 6 out performed the 8 due to the emissions stuff that was added on just my
 
I may be wrong here but in the 80's I do believe the 6 out performed the 8 due to the emissions stuff that was added on just my

What are you some kinda "Benedict Arnold" or defector?:laugh:
The V8 never had less power than the the 6, even in the dark days of emissions controls. The 6 was emission controlled too. The worst numbers ever recorded for AMC engines was in the bicentennial year of 1976 the 6 was pulled down to 110hp, 195 lbft & the V8 was 120hp & 220 lbft.:cool:
 
I may be wrong here but in the 80's I do believe the 6 out performed the 8 due to the emissions stuff that was added on just my

BTW 81' was the final year for a V8 CJ.;) 71amc_specs_&_tuneup_data.webp

1974engineperf.webp

1974enginespecchart.webp

enginespecchart.webp
1980-1981 — GM 151 , AMC 258 i6 / 4.2l , AMC 304

In 1980 AMC added the GM 151 "Iron Duke" to the lineup as the stock engine option in CJ-7s. The GM 151 (2.5L) inline 4 engine is actually a Pontiac engine designed to replace the Chevy "Iron Duke" I4 engine. The engine does have the Chevy bell housing bolt pattern though. The engine is manufactured by GM and uses a cast iron block and cylinder head with hydraulic lifters and 5 main bearings. The GM 151 cetainly is not a screamer, the AMC I4 has much better HP and torque ratings. The GM 151 has the intake and exhaust manifolds on opposite sides of the cylinder head, but the AMC 150 has the intake and exhaust manifolds on the same side of the cylinder head. The AMC 258 i6 / 4.2l Remained unchanged in 80 and 81, the AMC 304 had a minor performance decrease.

GM 151 I4 AMC 258 i6 / 4.2l I6 AMC 304 V8
Bore x Stroke 3.75" x 3.50" 3.75" x 3.90" 3.75" x 3.44"
Displacement GM 151 (2.5L) AMC 258 i6 / 4.2l (AMC 258 i6 / 4.2l ) AMC 304 (4.98L)
Compression Ratio 8.2:1 8.3:1 8.4:1
Horsepower (net) 82@4000 110@3500 125@3200
Torque (net) 125@2600 195@2000 220@2400
Main Bearings 5 7 5
Valve Configuration OHV OHV OHV
Fuel Rochester staged 2bbl 1bbl and 2bbl 2bbl
 
BTW 81' was the final year for a V8 CJ.;)View attachment 2703

View attachment 2704

View attachment 2705

View attachment 2706
1980-1981 — GM 151 , AMC 258 i6 / 4.2l , AMC 304

In 1980 AMC added the GM 151 "Iron Duke" to the lineup as the stock engine option in CJ-7s. The GM 151 (2.5L) inline 4 engine is actually a Pontiac engine designed to replace the Chevy "Iron Duke" I4 engine. The engine does have the Chevy bell housing bolt pattern though. The engine is manufactured by GM and uses a cast iron block and cylinder head with hydraulic lifters and 5 main bearings. The GM 151 cetainly is not a screamer, the AMC I4 has much better HP and torque ratings. The GM 151 has the intake and exhaust manifolds on opposite sides of the cylinder head, but the AMC 150 has the intake and exhaust manifolds on the same side of the cylinder head. The AMC 258 i6 / 4.2l Remained unchanged in 80 and 81, the AMC 304 had a minor performance decrease.

GM 151 I4 AMC 258 i6 / 4.2l I6 AMC 304 V8
Bore x Stroke 3.75" x 3.50" 3.75" x 3.90" 3.75" x 3.44"
Displacement GM 151 (2.5L) AMC 258 i6 / 4.2l (AMC 258 i6 / 4.2l ) AMC 304 (4.98L)
Compression Ratio 8.2:1 8.3:1 8.4:1
Horsepower (net) 82@4000 110@3500 125@3200
Torque (net) 125@2600 195@2000 220@2400
Main Bearings 5 7 5
Valve Configuration OHV OHV OHV
Fuel Rochester staged 2bbl 1bbl and 2bbl 2bbl

Class dimissed.:notworthy:
 
You know it just dawned on me. I think Horn may not like l6's. Perhaps he was abused by one when he was a kid? Should we do an "intervention" with deprogramming and counseling?:laugh:
 
The big question: What are you going to DO with that Jeep? If it's gonna' be a highway Jeep, give it a AMC 232 i6 for slightly better fuel efficiency. If it's gonna' be a driveway straddler, put in whatever's cheapest. If it's gonna' be an extreme-conditions offroader or a racing Jeep, go with the AMC 304 /360. If it's gonna' be anything else, treat yourself to a AMC 258 i6 / 4.2l .
 
You know it just dawned on me. I think Horn may not like l6's. Perhaps he was abused by one when he was a kid? Should we do an "intervention" with deprogramming and counseling?:laugh:

My wifes YJeep has a 258Ci 6 banger With a Holley4barrel, Offenhauser intake, Cilfford Reasearch 6 into 2 headers & MSD6AL Ignition.
I'm a HotRodder at heart & I've found V8's cheaper & more rewarding.
Besides I think about a 6, but then "Gee I coulda had a V8!":laugh:
 
I can not argue with your logic at all. I guess, for me, it’s a case of having spent the last 30 something years with a AMC 258 i6 / 4.2l I have grown comfortable with it. You know the line as well as anybody “if I have to explain it to you, you won’t understand.”:D It's a AMC 258 i6 / 4.2l thing.

My wifes YJeep has a 258Ci 6 banger With a Holley4barrel, Offenhauser intake, Cilfford Reasearch 6 into 2 headers & MSD6AL Ignition.
I'm a HotRodder at heart & I've found V8's cheaper & more rewarding.
Besides I think about a 6, but then "Gee I coulda had a V8!":laugh:
 
I can not argue with your logic at all. I guess, for me, it’s a case of having spent the last 30 something years with a AMC 258 i6 / 4.2l I have grown comfortable with it. You know the line as well as anybody “if I have to explain it to you, you won’t understand.”:D It's a AMC 258 i6 / 4.2l thing.

I hear you, 26 years ago I met my wife.
I was driving a 81' CJ5 Renegade .
It was Longhorn orange with 4"lift & a 401V8, 4-speed, Holley 4 barrel, headers & dual exhaust. Bigger tires, more lift, more wheelbase, but basically the same Ol'Jeep CJ.;)
 
Sounds like you guys are about ready to Hug but I guess Real Texans don't do that!:D
From the land of fruits and nuts......
 

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