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Valve cover question


jvd
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Question about the valve cover on my 91 comanche with a 4.0. I have a donor 94 4.0 xj engine sitting, waiting to be rebuilt (this winter) and noticed that they have different valve covers. The valve cover on the 91 has the quarter turn ccv valve and air intake valve, similar to a 90 and 87 4.0 I had. The 94 ccv valve and air intake valve are not quarter turn, not sure how they come out, haven't investigated yet. So the question I have, are the engines still the same, are they both the H.O. 4.0 or is the 91 a mix and match of parts from the renix era? The build date on the 91 is 11/90. I figured the 94 would be a plug and play with the 91 system now i'm not to sure. I know one way to tell if the 4.0 is H.O. is that the trottle body is mounted with 4 bolts and renix is 3 bolts. The 91 has four bolts, just confused with the valve cover. Thoughts?

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Should work fine. Your 91 is an HO. They changed the way the valve covers were set up over the years... my brother's 98 is working fine with a 91 4.0 with 91 valve cover.

 

If you think it might be a problem, just put your 91 cover on the 94 motor. Good chance it needs a gasket anyway.

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Question about the valve cover on my 91 comanche with a 4.0. I have a donor 94 4.0 xj engine sitting, waiting to be rebuilt (this winter) and noticed that they have different valve covers. The valve cover on the 91 has the quarter turn ccv valve and air intake valve, similar to a 90 and 87 4.0 I had. The 94 ccv valve and air intake valve are not quarter turn, not sure how they come out, haven't investigated yet. So the question I have, are the engines still the same, are they both the H.O. 4.0 or is the 91 a mix and match of parts from the renix era? The build date on the 91 is 11/90. I figured the 94 would be a plug and play with the 91 system now i'm not to sure. I know one way to tell if the 4.0 is H.O. is that the trottle body is mounted with 4 bolts and renix is 3 bolts. The 91 has four bolts, just confused with the valve cover. Thoughts?

 

Both engines are OBDI and compatible with each other. Both valve covers will also fit each engine as long as you use the correct correct CCV fittings. :cheers:

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