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Discussion Starter · #1 ·
I’m a rookie when it come to ‘years’ and ‘types’ of Ford DOHC heads, so any help you might be able to give me would be greatly appreciated. I just came across two pairs of DOHC heads. These heads have two intakes ports per cylinder. Any idea what year(s) engine they came off of?
Second, if the after market cams only lift to approx. .460", why are these ‘ported heads being flow to .550"?

Thanks
 

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I am ASSuming you mean the heads with the oval and square ports on the intake side of the head. I know 96-98 Cobras ran them, not sure if the 93-98(?) MarkVIII's did tho.

As for porting specs, your guess is probably as good as mine. I always want a complete flow sheet to determine if the porter/style of cylinder head is what I want and go from there. :)

Brian
 

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Discussion Starter · #3 ·
Thanks, so if I'm on the right track here, the 5.4's have the oval/ single port inlets and out flow the duel port inlets? By chance are these duel intake ports an emissions thing? Are they worth have ported as apposed to purchasing later model 5.4 heads? I'm trying to put together why Ford would build single and duel ports when looking at the duels it appears that they wouldn't be cost effective to produce. I might be just think out loud here.

Bob
 

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The 96-98 Cobra and the lincoln uses the dual runner heads.

In 99 Ford went to a tumble port design with a single large port, and that is what they used on the 5.4 Navigator.

They actually flow more CFM than the 99+ heads but dont seem to make as much torque.

The dual ports are exceptional when ported my flow over 290cfm on the intake at .450 and 320 cfm at .500
 

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The reason heads are flowed to .550" lift is because of the rocker arms, (or cam followers in our case) The "rocker" ratio on a modular is 1.8 So if the cam lifts .450" then actual valve lift is .810 Hope this helps answer your question.
 
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