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304 vs 360 heads |
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AMCGreen
Supporter of TheAMCForum Joined: Sep/21/2021 Location: Elliston, VA Status: Offline Points: 61 |
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Posted: Jul/03/2022 at 10:21am |
I am very much the novice when it comes to this stuff so please bear with me.
I have a 72 Javelin SST with 304 A/C Power steering, automatic transmission
I've read that the heads are interchangeable (specifically 304 to 360). What would be the other changes that I would expect? Will it affect timing, carburation? etc., etc. Can I use the same pistons? Different rings? I'm not looking to build a high performer. just a daily driver Please advise. Thanks , Ron |
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purple72Gremlin
AMC Addicted Charter Member Joined: Jul/01/2007 Location: Illinois Status: Offline Points: 16591 |
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The bigger valves may hit the cylinders the basic casting is similar.
Rings dont interchange because the bore is different sizes
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amcfool1
AMC Addicted Joined: Jun/18/2011 Location: roanoke va Status: Offline Points: 1071 |
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hi, the short answer is no. 360 heads CAN be made to work on a 304, but imo, not worth doing. If keeping the 304, and the heads are being rebuilt anyway, the way to go is to use SBC valves, 1.84 IN, 1.5 Ex. Valve length is within .002" , stem diameter is different, so new guides will be needed, a good deal anyway. good luck, gz
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george z
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AMCGreen
Supporter of TheAMCForum Joined: Sep/21/2021 Location: Elliston, VA Status: Offline Points: 61 |
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George Z,
thanks for the info. I notice your from Roanoke, I live just down the road near Elliston. A couple miles off exit 128 (RT 81) maybe we can compare notes someday Ron
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AMCGreen
Supporter of TheAMCForum Joined: Sep/21/2021 Location: Elliston, VA Status: Offline Points: 61 |
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Thanks. I have soooooo much to learn
Ron
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19611 |
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As amcfool1 said. The valves in a 360 are a good bit larger, so large that they are close to the cylinder wall when used on a 304. The top edge of the cylinder wall needs notching to clear the valves (notch doesn't go down below the first ring are), at least with a standard bore 304. With the valve so close to the cylinder wall a lot of the whole reason for a big valve is negated, as a good portion of the valve area is blocked by the cylinder wall. This is called "shrouding". So you get flow around 3/4 of the valve at best, more likely just 2/3. The slightly large Chevy valves increase flow a bit, and most importantly are still small enough ot get flow all around the circumference of the valve.
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Frank Swygert
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BassBoat
AMC Addicted Joined: Aug/29/2008 Status: Online Points: 1713 |
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The Chevy valves you want are 1.94, not 1.84. Indy cylinder head offered 304 heads with 1.94/1.5 valves, but supply may be dried up. Easy enough for a competent machine shop to do. In the long run, probably less expensive to switch to an entire 360. All you need is a block and pistons and heads. But you can usually find a useable 360 core for $500. You can notch the cylinders and run 360 heads on a 304 but it is not cost effective.
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bigbad69
Supporter of TheAMCForum Joined: Jul/02/2007 Location: Ottawa, Ont. Status: Offline Points: 6615 |
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If the 304 is essentially stock and you're looking for a little more power, I would start with a 4V carb and intake. Swapping in bigger valve heads won't give you much gain before you do this anyway.
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69 Javelin SST BBO 390 T10
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amcfool1
AMC Addicted Joined: Jun/18/2011 Location: roanoke va Status: Offline Points: 1071 |
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hey Ron, absolutely!, lets get together one weekend. As a matter of fact, I was just down there Saturday, visiting a friend off Bradshaw Rd. You can email me at: amcfool1@cox.net
see ya, gz
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george z
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ramblinrev
Moderator Group Joined: Dec/28/2008 Location: Wisconsin Status: Online Points: 11471 |
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What he said, and not to 'large' of a 4-barrel, in terms of CFM.
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74 Hornet Hatchback X twins (since 1977)
62 American Convertible (still worth the $50 I spent in 1973!) AMCRC #513, AMO #384 70 AMX 360 4-speed (since 1981) |
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