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AMC Intake manifolds

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Sjw83J20 View Drop Down
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    Posted: Jul/01/2014 at 12:24pm
I am currently building a 68-69 AMC 390 for my Jeep J20. I am having a problem finding an intake to use on it because it has 71 360 heads. Used these heads to keep the bigger valves and rocker studs but also have dog leg ports. Since the 68-69 390 is the short deck engine I don't know what I can use for an intake. I currently have a Edelbrock Performer that I was going to have machined to fit, but the machine shop wants like 300 to machine it. Since that is ball park what a new intake costs I was hoping maybe I could get a intake that will just go on with no machining. I was looking at the Air Gaps but Summit racing said that they only list it for 1970 and up. Any help would really be appreciated. Thanks.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote FuzzFace2 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/01/2014 at 12:59pm
I am no expert but any intake you buy will have to be machined.
I say this because 70-up heads have the center intake bolts in a different place. you can use an earlier intake and make the center bolt hole bigger (slot them) to work.
But as you know the angle will be off with the 70-up intake because of the deck height.
Also with any intake be it older or newer you should check the angle because with decking the block & heads angle can be off.
I would say if you have an early intake check the angle and if that is good thenI would slot the center bolts to fit the heads.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AMXFSTBK390 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/01/2014 at 1:16pm
Sam, Welcome to the AMC Forum! Great resource for information. We are fortunate to have many AMC Forum members willing to share their technical knowledge with other members.

Dave, If an early (68-69) intake is used with dog-leg heads on a 68-69 390 block, is there room to drill new center bolt holes in the intake manifold rather than slot the existing center holes? It seems easier to merely drill new holes than going to the trouble of slotting them. Or, does slotting them allow more allowance for the manifold bolts to thread into the heads? I ask because I am in the same predicament. Also, my 390 block was decked so the head gaskets will seal better.

Edited by AMXFSTBK390 - Jul/01/2014 at 5:24pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sjw83J20 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/01/2014 at 2:02pm
Well I know either way the 4 center bolt holes will need to be elongated, I should have been more clear. Will any intake bolt on without having the mating surfaces machined?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AMXFSTBK390 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/01/2014 at 5:55pm
Summit racing advertises the Edelbrock #60119 dog-leg heads on-line, and states the #60119 heads fit the 343,390 and 401. There are two bolt holes to choose from for the center intake manifold bolts. I find this confusing since the deck height is taller on the 401 block. One would think the 401 requires a wider intake than the lower deck height 390.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tsanchez Quote  Post ReplyReply Direct Link To This Post Posted: Jul/01/2014 at 6:00pm
Head would not be the issue, its the intake that is different for the deck height. The center bolts are different on pre 70 so as to make them less confusing. If you use a 70 + head on an older block you use the early intake and slot the holes. Or use a later intake and machine it to fit.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote FuzzFace2 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/01/2014 at 7:13pm
Originally posted by AMXFSTBK390 AMXFSTBK390 wrote:

Sam, Welcome to the AMC Forum! Great resource for information. We are fortunate to have many AMC Forum members willing to share their technical knowledge with other members.

Dave, If an early (68-69) intake is used with dog-leg heads on a 68-69 390 block, is there room to drill new center bolt holes in the intake manifold rather than slot the existing center holes? It seems easier to merely drill new holes than going to the trouble of slotting them. Or, does slotting them allow more allowance for the manifold bolts to thread into the heads? I ask because I am in the same predicament. Also, my 390 block was decked so the head gaskets will seal better.
I am not sure as I have never had to do this, all my blocks & heads are 70-up. It is only was I have seen posted and known of what needs to be checked when heads & blocks are cleaned up at rebuild time.
 
Originally posted by tsanchez tsanchez wrote:

Head would not be the issue, its the intake that is different for the deck height. The center bolts are different on pre 70 so as to make them less confusing. If you use a 70 + head on an older block you use the early intake and slot the holes. Or use a later intake and machine it to fit.
That was what I was trying to say.
Dave ----
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 69amxman Quote  Post ReplyReply Direct Link To This Post Posted: Jul/01/2014 at 9:32pm
I have a elderbrock performer on my 69 343 for the last 10 years now , all I had to do was elongate the center holes a little and she still runs strong
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jimster70 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/01/2014 at 9:34pm
I have a 390 4bbl intake with elongated holes I will sell you for $20 plus shipping
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