Re: [AMC-list] 4.0 manifold interchange, EGR, sportabout questions

[Frank Swygert <farna@xxxxxxx>]

1. Yes, and no. The cast iron 3 into 1 "header" used from 2000-2006 will physically bolt to the earlier head, but the ports are much smaller. You'd need to carefully port match the manifolds to the head or you'll create a restriction. The tubular manifold is much better. Just make sure the welds are sound and use a hanger at the floorboard right where the exhaust goes under the floor. If there are cracks in the tubes make sure you gusset the tubes when welding so they don't crack again (small triangular pieces welded in the angles). The intake will bolt right on with no problems.

2. If you have the cast iron pre 1980 intake it will bolt on, but you must grind/cut the flange where it bolts to the exhaust manifold off on the inside. All 4.0L heads must use a 4.0L exhaust manifold due to a change in the center exhaust ports. Besides that, the tubular manifolds are much better. File a notch in the bottom of the perches that the old intake sits on, or rather that fit over the dowels in the head. The perches need to rest ON the dowels, not with the dowels in the holes. File a small notch then test fit, file until the top edge of the manifold is even with the top edge of the head. A mid 1980+ aluminum intake is better, used on any AMC/Jeep, and Scout if they were using the AMC engines and still in production as of mid 1980. I think Scouts went out of production around 83-84??

3. Leaky ECU??? Not sure what you mean there! If you have the feedback carburetor it was a mistake, but most people do a "Nutter bypass" (search for it!) and unplug the ECU, or get a non-computerized carb. You need the ECU to set the needles for the Nutter bypass. If yours was already set (basically meaning it runs pretty good most of the time) then the ECU being gone isn't a problem. When the ECU and all the sensors are working right you actually get about the same power and a bit better MPG than the older carb without ECU. But it all has to be working just right, and the emissions stuff can be hard to troubleshoot and repair. So most just pull it all off.

MPG and high end power just don't go hand in hand! You pretty much have one or the other. For a street car what you really need the most is low to mid range power, not high end. Build for big HP numbers (high rpm) and you will lose a lot of mpg. Build for good low end torque and mid range power instead.

Best thing you can do is get a better cam to go along with the 4.0L head. The head alone WILL NOT give you a noticeable amount of power increase. Don't know where many people on the internet get that! You will see a substantial increase if you upgrade the cam/intake/exhaust to take advantage of the extra flow of the 4.0L head. Do all that and THEN you will see a 40-50 hp increase, mostly at the high end though. 20-30 hp on the low end to mid range will be VERY noticeable though. I'd go with a Comp 240H or 252H -- depends on how much you want to compromise mileage for power. The Xtreme cams require special springs which are very high pressure. Not good for a street car! You'll have to use special racing oil or an additive if you run the high pressure springs. With the High Energy cams you can run stock springs with regular oil with no problems, just run an additive for break-in and maybe the first oil change just to be safe.

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Date: Sun, 14 Nov 2010 20:29:17 -0600
From: "Eddie Stakes"<eddiestakes@xxxxxxxxxxxxxxxxxxxx>

Folks below are looking for some interchange and update questions for their 77 Hornet Sportabout. Anyone that can help out please feel free to comment and be sure to copy your reply to them as they would appreciate it...thanks in advance to all who might reply,
Eddie Stakes
----------
Hey Eddie,
I guess we are kinda strange birds with a penchant for Sportabouts, AMC's for that matter. If you got time I wanted to ask you a few more dumb questions;

1.. Will the 4.0 2000-2003 manifolds fit to the 4.0 H.O head?
2.. In the mean time would a 73 Scout manifold (-EGR) fit to my current head?
3.. When i put the HEI Dist on I tossed the leaky ecu away, was this a mistake?

I'm Most interested in MPG and high end power, The guy's at work all drive lifted F250's and 2500's huge 4x duelleys. I just want to drive the 600 or 700 miles a week in a cool station wagon. I'm gonna get a new carpet kit and upholstry for the front seat. I bought a great stereo at JC Wits. (takes a SD card and USB for my laptop. That means bluetooth and GPS.

Days are getting shorter and its getting harder to get the stuff done, But i would like to get it running for this year.



--
Frank Swygert
Publisher, "American Motors Cars"
Magazine (AMC)
For all AMC enthusiasts
http://www.amc-mag.com
(free download available!)


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