Difference Between 4.6L and 5.4L
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Senior Member
Joined: Jul 2001
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From: Marietta, GA
Difference Between 4.6L and 5.4L
hey, just a quick note. I've seen some questions about the differences between the 4.6l and the 5.4l v8. anyways, according to holley, "The heads are closer together on the 4.6 compared to the 5.4" so some things won't fit both engine because they "will not fit in the valley and align with the ports".
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Joined: Feb 2005
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From: Clermont, Fl
Im sorry to bring up such an old thread but I have some questions. I just recently blew the spark plug out of 5.4. 
But i tried to fix it with a insert and somehow I screwed that up as well...So my luck isnt running very strong right now. Well I am going to pull my motor (its easier to get to the heads that way and I am also in school to be a mechanic so its good practice) and I have some 4.6 heads laying around. I know the stroke is different between the two motors but the heads are the same right? So if I used the 4.6 heads and the 5.4 intake would it work? Just curious and thanks in adance for the help.
But i tried to fix it with a insert and somehow I screwed that up as well...So my luck isnt running very strong right now. Well I am going to pull my motor (its easier to get to the heads that way and I am also in school to be a mechanic so its good practice) and I have some 4.6 heads laying around. I know the stroke is different between the two motors but the heads are the same right? So if I used the 4.6 heads and the 5.4 intake would it work? Just curious and thanks in adance for the help.
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Joined: Jan 2007
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From: Naperville, IL
What year is your truck? Do you know what year engine the heads came off of? 96-98 modular heads will be NPI and 99-04 heads will be PI (this relates to all 2V heads).
Last edited by stein78; Jan 24, 2008 at 09:18 PM.
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From: NewYork
Not Exactly....
The 4.6 and 5.4 heads are interchangeable, but you will need a set of valve covers if your 4.6 heads are not from a truck (winsor). The number of valve cover bolts is different. Also the front timing cover bolts on a 4.6 are 8mm while the 5.4 bolts are 10mm.
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Joined: Oct 2005
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From: MI
Originally Posted by stein78
What year is your truck? Do you know what year engine the heads came off of? 96-98 modular heads will be NPI and 99-04 heads will be PI (this relates to all 2V heads).
Not exactly, if your talking truck motors- 2001's were Power Improved, if they came from a 4.6L block. - 99 PI's were on 5.4L blocks only
Last edited by jbrew; Jan 24, 2008 at 09:44 PM.
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Joined: Dec 1997
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From: Windsor,Ontario,Canada
4.6
97-98 Mostly Windsor engines. 99+ mostly Romeo engines.
97-00 Non Pi heads
01+ Pi heads
5.4
All Windsor engines
97-98 Non Pi heads
99+ Pi heads.
All engines
03 Redesigned Pi heads with more threads to keep plugs in place.
At any given time Windsor may have been assembling Romeo engines.
97-98 Mostly Windsor engines. 99+ mostly Romeo engines.
97-00 Non Pi heads
01+ Pi heads
5.4
All Windsor engines
97-98 Non Pi heads
99+ Pi heads.
All engines
03 Redesigned Pi heads with more threads to keep plugs in place.
At any given time Windsor may have been assembling Romeo engines.
Member
Joined: Jan 2007
Posts: 67
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From: Naperville, IL
Check out this link, all the 2V modular engine info you could ever need:
http://www.babcox.com/editorial/ar/eb40228.htm
http://www.babcox.com/editorial/ar/eb40228.htm
