The Ultimate 304... - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 12-20-1999, 09:43 PM Thread Starter
 
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The Ultimate 304...

The ultimate AMC 304 is a 360.
The GOOD:
The 304 and 360 share a number of common components, including motor mounts, engine mounts, and accessories.
The 360 heads have large 2.02" intake valves, 1.60" exhaust valves, 4 groove valve locks and 3/8" valve stems.
The 360 valve guides don't protrude into the valve bowl, and have huge intake and exhaust runners.
Edelbrock makes a matched cam/lifter/intake package for this family of engines.
Most of the hot rod catalogs offer piston & ring packages.
The 360 is everywhere because it was offered in the wagoneer.

The BAD:
The '74 to '78 304/360 have the same cast iron crank. No forged steel was available from the factory.
The '74 to '78 304/360 have cast iron connecting rods. No forged steel rods are available from the factory.
The '74 to '78 360 heads have thin castings, pedestal mounted rocker arms, and not much chance for easy rocker arm upgrades.
The 304 and 360 heads will NOT interchange! You will do engine damage!
A set of aftermarket rods will set you back about $800 to $1200. Forged steel rods are a must if you plan to rev the engine more than 3500 RPM, add a nitrous oxide system, or supercharge the engine.
The '74 to '78 304/360 block only came in a 2 bolt main cap version. Two bolt mains are only good to about 350 HP, and only if you use good studs.

The UGLY:
The '74 to '78 cylinder case (block) seems to have a problem with shifted sand castings. Sonic checking indicates that the cylinder wall is nearly too thin to use at the base of the cylinder before boring. (12 checked before finding 1 good block for boring)
Any attempt to machine the large pad between the center two exhaust valve guides, (for say, push rod guide plates) will result in cracks to the water jacket below. The material is too thin to machine nearly anything off of.
Pedestal mounted rocker arms and 5/16" rocker bolts don't lend them selves well to upgrades.
The motorcraft distributor is alright for an ignition trigger, but the duraspark box has to go!
The motorcraft 2bbl. carb is an utter waste of time.



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post #2 of (permalink) Old 12-20-1999, 10:06 PM
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Re: The Ultimate 304...

I AM BUILDING A 360 WITH 304 MATADOR CRANK, PEOPLE TELL ME STROKE THE SAME, BUT HANDS ON 304 CRANK FLUSH WITH TOP OF CYL. WALLS VS 360 CRANK WHICH IS ABOUT 3/8TH LOWER DO YOU HAVE ANY INFO WHICH MIGHT HELP ME THANKS

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post #3 of (permalink) Old 12-20-1999, 10:40 PM Thread Starter
 
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Re: The Ultimate 304...

Both the AMC 304 & 360 crank shafts are 3.44" stroke.
I don't know what a crank 'Hand' is.... Or how anything on the crank might come to the top of the cylinder.

I think what you might have is a 401 crank. The stroke is longer on the 401 compared to the 360.
Look for a number casted right into the side of the cylinder case (block) just above the oil pan rail. Numbers about 1 1/2" high. That is the CID displacement of the block. Look to see if your donor engine is a 360 or 401, and if the engine you are working on is actually a 360.
There are 6 engines in the family you are working on, 290-304-343-360-390-401. Outside dimensions are the same, so the serial numbers and the casting numbers are the only way to tell.

Good luck, hope I helped.

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post #4 of (permalink) Old 12-20-1999, 10:57 PM
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Re: The Ultimate 304...

THE BLOCK IS POSITIVE 360 I PUT CRANK OUT OF 304 IN 360 BLOCK USING 360 CONN. RODS AND PISTONS, WHEN I DID THE TOP OF PISTON IS FLUSH AT TDC,,, BUT WITH 360 CRANK THERE IS AROUND 300 THOU BELOW TOP, THE MOTOR 304 CAME OUT OF A MATADOR AND THATS ABOUT ALL I KNOW. EVERYONE TELLS ME STROKE THE SAME SO I DONT KNOW

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post #5 of (permalink) Old 12-20-1999, 11:09 PM Thread Starter
 
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Re: The Ultimate 304...

From everything I've read and heard from reputable sources, the cranks are the same.
The crank I'm using in the 360 was ordered as a 304 crank. The book says both are 3.44" stroke, with the main and rod journals the same.
Maybe someone switched the cranks before you got to it.
I'm using dished pistons, for about 9.5:1 compression. I just went and checked, and the 304 and 360 rods are the same length.
The 304 should have a stock bore of 3.75" and the 360 should have a stock bore of 4.080".
I can't tell you what you might have.
Did you check the stroke on the cranks yet? Rod length?
It doesn't look like I'm going to be much help...
Good luck.


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post #6 of (permalink) Old 12-21-1999, 06:45 AM
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Re: The Ultimate 304...

Team Rush..........didn't you forget the 390? Unless AMC made a special block for the 390 ......it too belongs among those you mentioned.

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post #7 of (permalink) Old 12-21-1999, 07:55 AM
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Re: The Ultimate 304...

just curious...what kind of engine damage will occur if you put 360/401 heads on a 304?? i have heads from a 401 on my 304..really screams like this too... i have about 40000 miles on the engine now....

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post #8 of (permalink) Old 12-21-1999, 09:53 AM
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Re: The Ultimate 304...

Someone (not me) alleges that you are doing the impossible......due to the small bore of the 304....and the bigger combustion area of the 401.

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post #9 of (permalink) Old 12-21-1999, 03:25 PM
 
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Re: The Ultimate 304...

From what the original post is saying the 74-78 blocks are bad,but what about the 72 block?I'm running the 72 360 engine with the 304 intake,carb and dist in my 76 cj-5.Oh well just one more question on the pile of unanswered ones!

Ben

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post #10 of (permalink) Old 12-21-1999, 05:49 PM
 
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Re: The Ultimate 304...

the 290 became the 304 after a longer stroke, as the 340 became the 360 after alonger stroke..

its possible youve got one of these earlier cranks, someone swapped it into the motor you have now...



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