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258 head? |
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purple72Gremlin
AMC Addicted Charter Member Joined: Jul/01/2007 Location: Illinois Status: Offline Points: 16614 |
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It's not a straightforward swap.......you'll have to change the manifolds....among other things...
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billd
Moderator Group Forum Administrator Joined: Jun/27/2007 Location: Iowa Status: Offline Points: 30894 |
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I owuld not mind doing that on my sx eventually, but for now, I just want to get it up the end of the driveway!
I'll start collecting the parts to make the swap, however............
OK, can one tell the differences between HO and ordinary on a 4.0 head by looking?
What years or vehicles used them?
Would a non-HO head be better than stock 258 head?
I can always drive a head to Nevada, IA to get a head ready to bolt on (assuming I find one).
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purple72Gremlin
AMC Addicted Charter Member Joined: Jul/01/2007 Location: Illinois Status: Offline Points: 16614 |
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Bill
Think 1987-'90 are the non-HO heads........'91 - up are HO......*I think*
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biscuit
AMC Apprentice Joined: Sep/10/2007 Status: Offline Points: 27 |
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yep intake and exaust i would like fuel injection anyway. the only thing that worrys me is the oiling if just swaping the lifters and pushrods will fix this?thanks again
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19689 |
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Purple is correct -- 87-90 = "standard" 4.0L, 91+ = HO. If the intake and/or exhaust manifold(s) is one you can easily tell the difference -- the standard 4.0L has an EGR valve and tube on the "header", the HO does not.
There's not that much difference between the standard and HO heads. The intake ports on the standard are about 3/8" higher than 232/258 intake ports to get a smoother flow into the head. The HO has the intake ports raised another 1/8" for the same reason -- a bit better flow. There is a 13 hp difference between the standard and HO engines, but it's not all in the head. The camshaft is advanced 2-3 degrees and the EFI program is tweaked. This makes a bit more power, but also moves the power output a little higher in rpm. The difference in power isn't as great if you run the HO engine at the same rpm as the standard. The head should add no more than half the gain -- maybe 5-7 hp, but that's just a guess on my part. It's not worth passing up a good deal on a 87-90 4.0L head for a later one, but if you're paying about the same price you may as well get a few extra ponies. It's definitely worth changing a 258 head for ANY 4.0L head though. |
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Frank Swygert
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