Jeep head swap?

M

MustangSix

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Anybody got a 258 or 4.0 Jeep head gasket handy? How far off are the bore centers?

Seems to me that the 4.0 Jeep head can be pretty well developed and it happens to share the same port layout as a 200/250 so a stock cam layout would work. The water passages on one side would need to be blocked, but that's done on 258 conversions, so no new ground there.

It would face the other way so the water outlet would have to be swapped but there's already an opening. Tap two holes.

So it comes down to bore spacing. The Jeep bores are fairly small too. Is it possible that the bore spacing is close enough to be feasible to do a swap?

jeephead.jpg
 
I don't have gasket here but that head looks like a real possibility. The bore on the 232/258 is 3.75 so thats a difference of about 1/16". If every thing else was equal and you center the head on cyl. 3&4 should be off about 3/16" on the ends. The other thing is bolt spacing across the head.
 
Next you'll be wanting to install a 12-port head off a 1985 Holden EFI... Same bore spacing as Ford!
 
What about the Aussie cossflow head. I know it's not supposed to fit but it looks to me like it would bolt right on. Now I'm new here so maybe you all have gone over this before. Would'nt it be possible to grind notches in the block for pushrod clearance. On the other side you could plug the steam holes and re-drill them closer in. The holes may have to be smaller because of the narrower deck but on many engines the actual holes in the gasket are smaller anyway. Just thinken......
 
The head bolts on, but the block is too narrow on the pushrod side. The crossflow block is 1/2" wider for clearance. I have been working on a mod but I don't get consistent results and have trashed six blocks to date. :( I think I've finally got one good one welded up and will eventually get around to finishing the machine work (time and money).
 
What does the extra width do in relation to the head? In other words, why do you need the extra 1/2 inch clearance for?
 
The bore spacing should be about 4 3/8. Head bolt spacing---4 3/8 front to back on center and 3 7/8 from side to side on center. Head is 6 5/8 wide and 27 5/8 long. Hope this helps.
 
Canted valve, Cleveland style heads can fit on to a pre-cross flow original American block if you are prepared to do the following:

1. Cut a ground steel plate 300 thou thick equal to the stock Aussie Crossflow headgasket. Have a machinist cut 3.68 inch (or nominal bore size) piston holes at the stock 4.045 inch bore spacing, mildly chamfered at the top to remove the craggs. Very importantly, the top surface must duplicate the Aussie Crossflow, and the base the non-cross flow American spec block. The 300 thou thickness should be tappered. Use two part "Araldite" glue and bond this to the block using an appropriate torque plate or head. The thinest application that can do the job

2. Machine new longer studs for the cylinder head.

3. Hone or overbore to cut the mating surface clear of glue.

4. Cut the existing non cross-flow block back to allow a new set of 300 thou longer pushrods to clear the side of the block without hitting it. Because the Cross flow has "porcupine" canted valves, the inlet and exhast pushrods are at least 10 degrees apart in a vertical plane and this is why the Aussies had to do a re-jig of the block to suit.

5. Adding 0.3" to the block has an advantage. You now can add narrowed 300 Ford 6 rods to stock 250 six pistons and stock 250 crank. Now that nasty 1.505 to 1 rod length to stroke ratio can be fixed with a better 1.588 to 1 ratio. The 300 Ford rod is 6.209 inches, not 5.885 inches like the 250. This reduces side loading the block, and reduces the frictional horsepower loss incured due to the side thrust. The engine is also smoother and more able to rev. The long stroke nature of the six always yields good low end torque. The 25 thou or so deck register the stock US 250 piston has in the block is now a perfect zero deck, so pistons may need some milling if your cam is a biggie or you cant find the right grade of gas!
 
Flying Kiwi. :!:

No offence, but can you send me 1/2 pound of what you're smokin. :roll:
 
I helped a buddy pull a 4.0 Jeep head the other day and I have a 200 head sitting idle in the garage. I'll put 'em side by side and see if they look similar. If that's promising I'll bring the 200 head to the junkyard and slap it down on the 4.0 block and see if things line up.
If that still looks good I'll see about grabbing a 200 block and borrowing the Jeep head.
I'll try to find a little time over Thanksgiving break, we'll see how it goes, I'm gonna be busy doing the job search thing too.
Ben
 
I picked up the head gasket from my friend's Jeep. Tomorrow morning I will hold it to the bottom of the 200 'turd' head and see if it looks like there are enough similarities to consider going on. The bores outlines from the Ford gasket are visible on the bottom of the head so I'll have some indication of how things line up.
More tomorrow.
Ben
 
The important thing would be for there to be enough for the thing to seal between cylinders. Actually, I was thinking of using a Ford gasket with the Jeep head.

The chambers wouldn't have to be centered on the bores, so a little offset would be ok as long as you had sufficient seal between cylinders. In fact when the Jag 3.8 was enlarged to 4.2, the bore centers were moved but the head remained the same.

Either the head or the block or both would have to have the head bolt holes modified.

Hmmmm..... :unsure: probably just another crazy idea....hybrid engines....
 
I know nothing about the Jeep engines, and not a whole lot more about the Ford engines, so here's my question... if the Jeep head is a superior design, worthy of a significant amount of agony to mate to a Ford block, why not just transplant the entire Jeep engine? or would that be sacrilegious?
 
Actually, that's where the thought process was leading me, but the one thing that keeps leading me back is the fact that the 'ol Jeep 4.0 or 258 is a big tall hunk of metal. It would be easier to transplant a 300.

But if a Jeep head would fit the lightweight, compact 200 block, that would be something.
 
Aw, Jack... Just whack in an Aussie 265 Hemi. Hey, Mopar are like cousins. :roll:
 
Ranger,

Unless I'm mistaken, you wouldn't need to sleeve Kiwi's mods. The rings don't come up that high in the bore.
 
Well, I didn't use a measuring device of any kind, so I can't say by *how much* it won't work, but the jeep head gasket is a bit longer than the Ford head.
I think we'd have to find a way to work with siamesed cylinders if we really wanted this; the bores are further apart on the Jeep head.
The head gasket is a little over an inch longer than the Ford head; no matter where you start/stop/center the gasket it looks like one of the Jeep bores will be in open air, or very very close.
I suppose you could build a shim plate a la the 2-barrel adapter, but I think it wouldn't be worth the effort! :LOL:
Oh well, it was worth the thought...I wonder about the Jeep head and a 300?
Ben
 
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