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I would think swapping in PI cams in a NPI engine should be a mild HP boost. I believe they can't just be swapped without some mods. Is the retainer to valve seal clearance enough for the PI's extra lift as an example. Anything else that needs to checked or changed?
 

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It will be a direct swap on 96+ NPI heads. If you have 94/95 heads, they will cause coil bind issues and can't be used.
 

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His is a 97. It's a direct swap. Unbolt your cam covers, unbolt cam gears, swap camshafts, bolt up cam gears with the PI cam bolts (they are different than NPI), bolt down cam covers, reinstall valve covers, done.
 

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His is a 97. It's a direct swap. Unbolt your cam covers, unbolt cam gears, swap camshafts, bolt up cam gears with the PI cam bolts (they are different than NPI), bolt down cam covers, reinstall valve covers, done.
Not quite. You left out the most important part.
 

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WOT Junkie and avid corn burner
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Oh yeah, get that tool you can use to wedge in between the timing chain on each bank so the chains don't move. You can't let the tensioners expand out.
 

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I'm a believer in removing the cover these guides get old and worn I like to take it all apart inspect it, verify correct timing and well....basically..do it the hard way. When I'm done I don't have to worry about it that way. I find the metal tensioners are usually ok to reuse but cleaning them out can't hurt. I will warn however make sure to put the chains back on in the direction and side they were on before. It helps to align the marks before you take it apart then mark the chains. My buddy tried to do it without doing that and the chains failed in a couple weeks.
Alan
 

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Well, for what it's worth, mine has been doing just fine. The way I outlined it, although slightly out of order, is essentially how RobertP did mine. It was an easy swap and he didn't have to take the timing cover off.
 

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Well, for what it's worth, mine has been doing just fine. The way I outlined it, although slightly out of order, is essentially how RobertP did mine. It was an easy swap and he didn't have to take the timing cover off.
I'm not saying it can't be done, the concern is that if the tensioner pops out even one click the guides will fail quickly.
Alan

unless you change the springs.
In order to change the springs ( to springs that would provide enough clearance) you would have to have the heads machined to the specs of 96+ heads and use those components. It is not possible on stock pre 96 heads without more work than the heads are worth.
Alan
 

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I'm a believer in removing the cover these guides get old and worn I like to take it all apart inspect it, verify correct timing and well....basically..do it the hard way. When I'm done I don't have to worry about it that way. I find the metal tensioners are usually ok to reuse but cleaning them out can't hurt. I will warn however make sure to put the chains back on in the direction and side they were on before. It helps to align the marks before you take it apart then mark the chains. My buddy tried to do it without doing that and the chains failed in a couple weeks.
Alan
In order to change the springs ( to springs that would provide enough clearance) you would have to have the heads machined to the specs of 96+ heads and use those components. It is not possible on stock pre 96 heads without more work than the heads are worth.
Alan
as always alan good information and advice. perhaps one day i will get a complete grip on the intricacies of the 4.6 mod motor.
 
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