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258 w/ 4.0 head, or 4.0 engine swap?

Printed From: TheAMCForum.com
Category: The Garage
Forum Name: AMC 6 Cylinder Engine Repair and Modifications
Forum Description: AMC-made I-6 engine mechanical, ignition and fuel from basic repair to high-perf modifications
URL: https://theamcforum.com/forum/forum_posts.asp?TID=14765
Printed Date: Mar/28/2024 at 2:38am
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Topic: 258 w/ 4.0 head, or 4.0 engine swap?
Posted By: zeidrach
Subject: 258 w/ 4.0 head, or 4.0 engine swap?
Date Posted: Nov/21/2009 at 5:51am
I have a 1972 AMC Hornet, with the 258 and a 904 chrysler transmission. I've been looking online for the past few hours into the 4.0 head swap. Looks fairly easy, I could either seal off the ports with JB weld or have them welded and the head resurfaced at my local Riebes.
 
Which will gain me more horsepower, a 4.0 head on a 258, or a whole 4.0? Either way the engine will be carbed, and I'll probably run the stock 4.0 header. I'm on a budget, so no fancy headers for me. There's plenty of 4.0's at my local pick and pull, and 1 258 in an 84 Eagle I could use if need be.
 
Should I use the aluminum 2bbl Eagle intake I have laying around here, with a motorcraft 2100(already own as well), or order the Clifford performance intake with either the 2 or 4 bbl adapter plate?


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http://i306.photobucket.com/albums/nn278/zeidrach/100_3101Small.jpg



Replies:
Posted By: Greyhounds_AMX
Date Posted: Nov/21/2009 at 6:02pm
From a displacement standpoint, the 258 wins, but if you're going to run a stock cam the 4.0L cam is going to be more agressive. Of course it doesn't have a fuel pump cam though so you'd need an electric fuel pump.
 
I think you're on the right track for a low buck and fun engine project.


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1968 AMX 390 w/T5


Posted By: zeidrach
Date Posted: Nov/21/2009 at 6:49pm
I'm leaning more towards the head swap, I can get one for cheap at pick and pull, plus I won't have to pull my engine. I could probably do it, but I don't have a hoist, soo...

If I go with the head swap, what intake should I use? Can I use the stock 4.0 intake and buy a carb adapter? Should I keep my eyes out for an Offy 4bbl intake on the cheap?

Right now, I'm in the middle of putting the original 1bbl intake on till I can afford the swap. I'm painting it the engine, the paint is drying as I type right now.

Also, I was thinking of buying a mild cam, can what would you guys recommend($50-$250 range)?


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http://i306.photobucket.com/albums/nn278/zeidrach/100_3101Small.jpg


Posted By: purple72Gremlin
Date Posted: Nov/21/2009 at 7:15pm
IMO, bore and stroke in 4.0 is much better.  but if you dont have the $$, well, then stick with the 258.


Posted By: Rodger
Date Posted: Nov/21/2009 at 10:13pm
Sir
 
I like the 2 bbl option.  Carb's are every where
and Stock Appearing 2 bbl Air Cleaner Housings
are more attactive when you open the hood
at a event that has other AMC Driver's around.
 
There is a pride in saying, " ... oh its just an
AMC Straight Six".
 
 
Rodger & Gabby
COS


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Rodger & Gabby
COS


Posted By: zeidrach
Date Posted: Nov/21/2009 at 10:28pm
Originally posted by Rodger Rodger wrote:

Sir
 
I like the 2 bbl option.  Carb's are every where
and Stock Appearing 2 bbl Air Cleaner Housings
are more attactive when you open the hood
at a event that has other AMC Driver's around.
 
There is a pride in saying, " ... oh its just an
AMC Straight Six".
 
 
Rodger & Gabby
COS


Which 2bbl do you mean, a motorcraft, or a stock one from an eagle? I have a motorcraft 2bbl around here, I had on the 258, but ran like poo.


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http://i306.photobucket.com/albums/nn278/zeidrach/100_3101Small.jpg


Posted By: Rodger
Date Posted: Nov/21/2009 at 10:42pm
Sir
 
AMC started using a 2 bbl Air Cleaner Housing, Carb and intake about 1972 on the 258's.  The six banger carb is better matched with CFM's to the cubes than something from a V8 and be drowning from being "over-carb'd" .
 
 
Rodger & Gabby
COS


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Rodger & Gabby
COS


Posted By: purple72Gremlin
Date Posted: Nov/21/2009 at 10:46pm
Originally posted by Rodger Rodger wrote:

Sir
 
AMC started using a 2 bbl Air Cleaner Housing, Carb and intake about 1972 on the 258's.  The six banger carb is better matched with CFM's to the cubes than something from a V8 and be drowning from being "over-carb'd" .
 
 
Rodger & Gabby
COS
Ive seen older 232's have 2BBL's  and the motorcraft swap is very common.


Posted By: Greyhounds_AMX
Date Posted: Nov/22/2009 at 9:18am
I think the later model aluminum intake with a Weber carb would be a good combo coupled with the 4.0L head and 4.0L factory header.
 
Add a hotter cam and you should be cookin'. The 4.0L head with bring your compression up as well, so you may need ot be selective on the cam. I've run the Crane HMV272 alot and like it alot, but a little higher stall converter would be nice with it. There are probably better choices for this combo.
 
If you make a cam change you'll need valve springs and retainers as well, though.


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1968 AMX 390 w/T5


Posted By: farna
Date Posted: Nov/22/2009 at 4:24pm
With a carb you're better off with the 258 and 4.0L head. As Chris mentioned, you'll get a little compression boost too. If you had to build a block I'd say use the 258 crank and rods in the 4.0L block with 4.0L stock pistons. That gives a bigger compression boost due to the longer stroke, and makes a 280 inch engine.

Some Jeep racers have been running carbs on the 4.0L intake. I don't know if they are buying or making adapters, and I don't know what carb -- I think it's a "souped up" 1V. That would certainly be the easiest to adapt!

I'd use a 1981-90 258 2V intake. You almost have to have one of those with the 4.0L head. you can run a Carter BBD 2V (pre smog!!) or a Motorcraft 2150 or better yet a Holley 2300. You need the small Motorcraft or Holley though. There were 350 and 500 cfm versions. The small Motorcraft will have "1.08" stamped in a circle somewhere on it. It was used on 289/302 Fords and 304 Jeeps. Can't tell you how to ID the Holley. Jets are hard to come by for the Ford, the Holley is the primary half of a Holley 4V -- easy to get help on tuning and all parts.


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Frank Swygert


Posted By: PavementPounder
Date Posted: Nov/25/2009 at 11:15am
If you do the head swap, I'd run the 99-up 4.0 intake. It has equal-length runners.


Posted By: zeidrach
Date Posted: Nov/25/2009 at 6:37pm
If I run the 99-up intake, is there a carb adapter? Aren't the injectors built intake on those as well? I want to run a carb on my car. Thanks!


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http://i306.photobucket.com/albums/nn278/zeidrach/100_3101Small.jpg


Posted By: TinMan
Date Posted: Nov/25/2009 at 6:55pm
Not sure on this, but if you're running a carb I think you'd want a carb intake (along with a cam that is designed for a running a carb). The fuel injected intakes were not designed to mix the fuel and air from the throttle body, they were designed for port injection.

Buy a carb intake and if you have to adapt the ports to match up then do so.

This is a 99+ intake for reference.


Posted By: farna
Date Posted: Nov/26/2009 at 8:09pm
The EFI intake works just as good as a carb intake with a carb. I don't know the exact procedures on converting one, only that some Jeep racers have been doing it. The 99 intake would be an excellent start, some large 1V like a Carter YF would be a good candidate for converting. Obviously the injector ports have to be sealed.

All that does seem like a lot when there should be plenty AMC/Jeep 2V intakes around. All you need is an 81-89 258 2V intake. Any Jeep with a 4.2L (258) will have one, and of course 81-83 AMC 2WD cars and Eagles. To mount one on a 4.0L head requires a simple notch below the normal dowel pin hole. The intake will rest on TOP of the dowel pins. The intake ports are raised roughly 5/8" above the old 258 ports, and that does the trick. You may need to make some steel plates and use them in place of the normal cupped washers used to clamp the manifolds on. I have some made from aluminum, but steel will be fine. A piece of 1" wide, 3/16" thick bar should do fine.  

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Frank Swygert


Posted By: PavementPounder
Date Posted: Nov/27/2009 at 11:13am
Originally posted by farna farna wrote:

All that does seem like a lot when there should be plenty AMC/Jeep 2V intakes around. All you need is an 81-89 258 2V intake. Any Jeep with a 4.2L (258) will have one, and of course 81-83 AMC 2WD cars and Eagles. To mount one on a 4.0L head requires a simple notch below the normal dowel pin hole. The intake will rest on TOP of the dowel pins. The intake ports are raised roughly 5/8" above the old 258 ports, and that does the trick. You may need to make some steel plates and use them in place of the normal cupped washers used to clamp the manifolds on. I have some made from aluminum, but steel will be fine. A piece of 1" wide, 3/16" thick bar should do fine.  


I just listed a few sets of these I had on the shelf.

http://theamcforum.com/forum/2bbl-258-intake-exhaust-manifold-sets_topic14922.html


Posted By: SnailPowered
Date Posted: Jan/23/2010 at 1:39pm
This hasn't been posted on in a while but are any of these aluminum heads? Or can I bolt a fuel injection manifold on the stock head? After reviewing some of the specs on the stock engine I am thinking about building a turbo-charged 232 block. I definitely want to switch to fuel injection too because carbs and turbo chargers don't like to mix so well. I am also wondering about ignition options.  I just got my Rambler, I am 23 years old and I have been into the tuner scene so my first thought was to use a Japanese motor that came turbo charged...I am far too proud of an American to do that though! So now I want to take the stock 6 cylinder and beat them with it. Any help would be immensely appreciated!

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1969 Rambler


Posted By: TinMan
Date Posted: Jan/23/2010 at 1:48pm
None of the OEM heads are aluminum, however Hesco does make an http://www.hesco.us/shop.asp?action=details&inventoryID=44115&catId=7735 - aluminum 4.0L head , but as you would expect it is very costly and that much money could be spent in better ways on the engine.



Posted By: SnailPowered
Date Posted: Jan/23/2010 at 2:46pm
Well, I was thinking about just getting the stock head ported out as big as I can and throwing a good cam with no valve overlap to suit the turbocharger. I will definitely hold my head high if I can manage to at least run with the modern day cars running my 41 year old technology lol. Well, other than the brand new Haltech and modern fuel injectors lol.

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1969 Rambler


Posted By: farna
Date Posted: Jan/23/2010 at 8:59pm
A carb DOES work well with a turbo -- unless you're throwing over 25 psi to it. I'd think you would start with something less than that. I do understand the desire for EFI though, especially since you're used to dealing with it in turbo engines. You're right on that edge where you are the opposite of most of the old guys on here -- they came up with carbs and don't like messing with EFI! I'm one of the "old guys" at 47, but I don't like carbs a whole lot. They work well when properly set up, just like EFI, and can make as much and sometimes more peak power. But they can't do it ALL THE TIME. EFI can with minimal maintenance in comparison. But I'm getting off topic!

Big ports aren't necessarily the best. The 4.0L head has SMALLER ports than older 258s, but flow so much better due to a much better shape and increased charge velocity. With pressurization the shape isn't as important -- pressurize the intake charge enough and you will have velocity!

Check this site for the best six cylinder head info:
http://members.tripod.com/~Mojo_Page/Headpg1.htm
It's a bit dated as it only mentions why the author hasn't moved on to a 4.0L head (I think he has now). Note that he shows the exhaust port of a 98 head (I think it was actually 99 that the real small exhaust ports were introduced, not 98, but I could be wrong -- 96 and earlier exhaust ports are definitely a little larger). Note also how much the intake ports were raised to reduce the radius of the port runner  by noting the height of the alignment dowel for the intake on the 4.0L and 258 heads. The bottom of the port was raised 5/8" (about 1/4" for 87-90 Renix heads, and additional 3/8" in 91 for the H.O. head).

Your best bet would be to do a 4.0L head conversion on the 232. You would have to measure the pushrods and of course get hollow ones. I believe pre 72 232/258/199 pushrods would be the correct length, but they are solid. Other than that it's just block the triangular casting wash-out ports in the water jacket along the right  side of the head.

Easiest way to run a turbo is semi-remote. Keep a stock type exhaust manifold and run a pipe under the oil pan to the front right side of the engine. Make a bracket to support the turbo there. It's been done several times like that. If you're worried about heat loss wrap the pipe going under the engine.  You should be able to easily run 20 psi like that, probably more. Sounds like you may know more about turbo engines than I do though.

You CAN run a 4.0L intake on a 258 head, but can't use the 4.0L exhaust without modification. The center two exhaust ports changed a lot, so you'd have to cut the flange from at least those two ports and make a new one to fit the old style 258 head.  For the 4.0L intake you might have to notch the top edge of the intake ports for the injectors, but I don't think so since the older ports are a bit larger. You would have to grind/file the alignment dowel hole out or drill a new one to properly align the intake. To run a 258 intake on a 4.0L head a notch is filed in the bottom of the "leg" where the alignment hole is to move the intake up higher.


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Frank Swygert


Posted By: SnailPowered
Date Posted: Jan/24/2010 at 12:17am
I said that a carb doesn't work well with a turbo because I am reading a book about how to tune and modify EFI systems and he goes through the functioning of a carb and all the problems that turbochargers cause with a carb. On top of that, I understand bar graphs on a computer screen and they're relation to my AFR better than twisting jet screws and changing jets. I had to deal with carbs  on my dirt bike and now I am all about running EFI simply for the ease and wide range of self-adjustability. Get the right sized fuel injectors to not lean out your engine and let the computer figure out how to make the AFR stay at a constant 12.5 (or so).

I want to port out because I would like to run higher RPM. I realize that idea is pretty much against the entire design of the AMC 6 cylinder but I have an obsession with really high revving engines. The sound of a Ferrari  V8 is like a woman...well, you know what I mean. :P I realize that there are limitations and I plan on pushing as far to the limitations as possible, until I hit 400rwhp. As my friend explained to me, an engine is just a big air pump and the power you can get out of it is a function of the air moving through it.

SO, Are there any after market heads that I could get that would have the exhaust on the opposite side? LOL, That would make things SO much easier for me with the turbo department. I am thinking that if all else fails I can get the intake and head ported out as much as I can (not polished, I plan on driving this to work sometimes) and then have the intake manifold and the headers/exhaust up to the turbo ceramic coated. I have seen Jeep turbo kits and I forgot about the ports being on the same side. Luckily, in a 69 Rambler there is plenty of room on either side of the engine to bolt up as big of a turbo as I would want.

I am also looking at the Hesco aluminum cylinder head for the simple reason it claims better flow...and a 30lb drop on one part installed sounds like an easy way to shave some of the pounds I am going to put back with my A/C (living in Arizona I never want to run a car without A/C hahahah). One of the problems is that it says you will need a shorter push rod? Does this still apply to putting that head on the 232? I should probably pay someone that knows what they are doing to do this crazy idea of mine, but the sense of accomplishment just isn't in it for me when I pay to get it done.

So, now that I have bounced around topic like a gerbil with espresso. In short, all recommendations are HIGHLY appreciated! I am going to need all the help I can get because I plan on putting all the wrench time in myself. I can't machine but I am confident that the rest of it I can manage. And all the broken parts along the way will tell the tale of my learning curve.

P.S. My other main reason to run the Hesco head is to use the 2001 and up distributorless ignition. the stand alone ECM I want to run can run a plug per coil, dual fuel injectors...and about as many other things as you really want to plug into it.


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1969 Rambler


Posted By: purple72Gremlin
Date Posted: Jan/24/2010 at 12:22am
The 4.0 will do high RPMs better than the 258...............................look at the bore X stroke..............between the two engines.


Posted By: SnailPowered
Date Posted: Jan/24/2010 at 12:51am
I have a 232, the bore is larger than the stroke so the potential for revs is higher. I also haven't looked at the 4.0 bore and stroke, I am growing more and more partial to keeping my stock block in the car...which is probably not the best idea lol. I know that the advances in metallurgy between 1969 and even 1990 were moving in leaps and bounds. If I can't make 400rwhp with a stock block then I will have to switch to a 4.0. What are the options for dropping the stroke on a 4.0?

Since I am in Iraq and have absolutely nothing better to do with my time (which is a lie that I keep telling myself) I looked up the bore and stroke and found that there were SOME engines that ran a 3in. stroke instead of the 3.5in stroke. I think they were saying that a 199 has the 3in and the 232 has the 3.5in stroke...is it possible to run the 3.0in stroke crank in my 232? I realize that I will be losing some of my displacement but contrary to popular belief, there is a REplacement for DISplacement, it comes in the form of a little metal fan that resembles a snail lol. I am looking for higher horsepower than torque, I am not trying to drag race my car.

As I go through and read this, can I get my 232 up to a 99mm bore? How far out can I bore this thing? Maybe, just maybe I can bore it far enough to make up for the loss in stroke and maintain a "rough" 232cid while improving my potential to rev. If I am losing, or have completely lost, my mind feel free to tell me. This is all a big crazy dream and I am a dreamer.


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1969 Rambler


Posted By: TinMan
Date Posted: Jan/24/2010 at 1:13am
If you go with the Hesco head, don't forget to use their thermostat housing.
Just for kicks, contact 505 Performance and ask for some information on their 4.0L turbo setups. You might be able to get some useful information out of it to keep in mind while building the turbo setup.


Posted By: SnailPowered
Date Posted: Jan/24/2010 at 1:28am
Well, since I will need to run the turbo to the other side of the engine I think I can get away with fabbing it all at my uncle's shop. My biggest problem with the base model that they show is that it is an air cooled turbo. I will  run one that is both oil and coolant cooled. Thank you for pointing that out though because I am sure that they will be a very valuable resource when I hit stumbling blocks along my way. I definitely didn't know about the thermostat housing either. I am thinking of buying a totaled Jeep and pulling the intake off along with all the EFI sensors that I am going to need. All this is a way down the road, as I said, I am in Iraq and when I am not forced to think about something else I either dream of buying a Harley and riding it all over heck and back, or putting a wrench to my Rambler and making it do things that it was never designed to do.


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1969 Rambler


Posted By: hoosieramc
Date Posted: Jan/24/2010 at 7:37am
199 Bore x Stroke 3.75x 3.00
232 Bore x Stroke 3.75 x 3.50
258 Bore x Stroke 3.75" x 3.90"
4.0 Bore x Stroke  3.88" x 3.41" 
 
So the 199 and the 4.0 have the largest bore shortest stroke combos.


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Posted By: poormansMACHINE
Date Posted: Jan/24/2010 at 8:23am
Wanting to get more from your 6's is great. Combining and bolting parts together is a good start. However there seems to be 2 words that aren't in the 6 builders vocabulary.

                                                           PORT MATCHING


Posted By: SnailPowered
Date Posted: Jan/24/2010 at 8:34am
I have moved this discussion to a new topic since I have traveled VERY far from the subject of this post. Thank you all for your help and http://theamcforum.com/forum/topic16185_post142568.html#142568 - here is the new post link.

http://theamcforum.com/forum/topic16185_post142568.html#14256

P.S. Port matching is definitely in the future of my project!


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1969 Rambler



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