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Discussion Starter #1
do i need new valve springs because i bought gt40p heads (off a explorer) and i want to use ford racing 1.7 roller rocker arms?

in 3 months or so i want a tfs1 camshaft but i thought i would upgrade to Trick Flow Specialties TFS-2500100 - Trick Flow® Valve Spring Upgrade Kits - Overview - SummitRacing.com when i get a cam and is it hard to change those and can you do it while there on the car.

last can i use my 1.7s when i upgrade to the tfs1 cam? or with i have valve to piston clearance issues
 

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do the valve springs now they are MUCH easier to change when the heads are NOT on the car..those springs are probably worn,and they're weak to begin with..IMO you should do it all at once,it really sux to put it all together then completely tear it back apart 3 months later to swap the cam and have to buy all new gaskets again..

that cam with 1.7's will give you roughly .530/.541 max lift..from my understanding,the P heads dont flow much past .500" lift so its really not beneficial to you to use 1.7's with that cam

also 1.7's with your stock cam isnt really going to give you any noticable gains,so IMO i would just buy a nice set of 1.6rr's,the TF valve spring kit and be done..then later down the road you can swap in almost any cam you like and not have to worry about adding .030" lift with the 1.7's

just my $.02...
 

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Yes, you do need better springs.

BTW, it's the other way around, since those stock heads are flow limited, you want to give them all the help they can get. Since a dwell style camshaft is out of the question, increasing lift allows them to be at/near highest flow capability point for a longer period of time in the cycle, compensating for their limitation. FYI... total valve lift has nothing to do with the possibility of PtV problems. In your case, the stock cam with 1.7/1.72 rockers would be a good alternative to look into. LUK
 

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Yes, you need better springs.
 

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Discussion Starter #5

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Stock-length pushrods should work fine, but you might want to buy the length checker one just to make sure.

Always use the valvesprings that are recommended for the cam, or ones with similar specs.
 
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