head interchange: 3.5L, 3.9L, 4.0L - Defender Source
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  #1  
Old April 16th, 2007, 04:02 AM
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Jason Herring
94 D90 ST #1253
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head interchange: 3.5L, 3.9L, 4.0L

Quick question - do the heads on these engines interchange? If so, are the valves the same size? Any issues running 3.5L headas on a 3.9L?

Thanks--
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  #2  
Old April 16th, 2007, 11:48 AM
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Charles Galpin
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Jason I am no expert, but I have been looking into options for rebuilding my engine and the answer is yes across the board afaik. There are 10 bolt and 14 bolt varieties, the 10 bolt being better I am told. I would imagine there may be valve size differences due to changes in displacement, but I don't know for sure.

hth
charles
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Old April 16th, 2007, 12:34 PM
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Jason Herring
94 D90 ST #1253
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I have the option to pick up some 3.5L heads nearly free, but a different option for 3.9L heads is about $300 (both would need machining as they are condition unknown). I'd be interested to know about valve size differences or port size differences, if they exist.

It's good to know they'll bolt on - but a port mismatch or too-small valves would not be helpful to performance :-S

Thanks for the reply~
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  #4  
Old April 16th, 2007, 12:43 PM
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Charles Galpin
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Yeah, best to wait and hear from someone who knows what they are talking about

charles
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  #5  
Old April 16th, 2007, 01:44 PM
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J. Michael McCaig
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I'm running '87 3.5 heads on my 2003 carbed 4.6 in my 110 with no problem.
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