4.0 head swap help

[jmbridges]

Hi all, still working on my 81 CJ7 rebuild. Currently reassembling the engine. Have decided to do a 4.0 head swap and have encountered an issue. My understanding was that I could reuse the intake manifold from the AMC 258 i6 / 4.2l , but when I was fitting it, there were clearly gaps between the new head and the old intake. See pics below. I assuming this means I need to get a new 4.0 intake, but just want to confirm that as all the discussions on this swap indicate you can reuse intake? Thanks

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[hole]

Not sure about original AMC 258 i6 / 4.2l intake fitting on a 4.0 head, but now would be a good time to think about MPI. Have you given Hesco a call? Those guys are a wealth of knowledge.

 

[hole]

Too funny, I just noticed where you are located. Hesco is in Birmingham AL as well.

 

[jmbridges]

Thanks, yeah they did all the machine work on my block. I am planning to put on a howell tbi system. The MPI systems - including hesco's - are about double the price of the Howell and I don't think worth the extra grand +. I was just confused about the intake as all the articles - including Tim Weaver's - say you can re-use the original intake. Still, I don't think it's feasible - or at least not smart - to run it with those gaps, so I guess I will just have to get a 4.0 intake.

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[yellow85cj]

The intake will fit fine. Looks like you are probably using the head alignment pins to line up the intake. The intake pin holes have to be set on top of the head pins. Have to Dremmel a bit so they sit correctly.

Don't think the 4.0 intake will work with TBI without, at the very least, adapters.

Use the AMC 258 i6 / 4.2l intake gasket as a template and you will see how it fits.

 

[yellow85cj]

Here is a pic with AMC 258 i6 / 4.2l gasket showing how it lines up.

 

[jmbridges]

Thanks, that's interesting. That's exactly what I was doing, seemed logical. I had not seen mentioned in any of the articles or discussions about having to make that modification. Thanks, saved me $AMC 150

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[yellow85cj]

One other place that may/may not need a little trimming. Where the intake meets the exhaust manifold. The corner of the intake may need a little trimming so that it seats correctly. Plenty of meat on the intake corner so no worries. Test fit the manifold with the exhaust manifold bolted on. If it doesn't seat exactly on top of the pins, you'll see where the corners need to be trimmed. Dremmal with sanding drum or grinding wheel does the trick.

Wash the intake and use a wire wheel on a bench grinder and then clear coat. Makes it pretty.

Black BBQ grill paint on the exhaust manifold holds up very well.

 

[jmbridges]

Sweet, thanks!