AFR head question
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From: Bristol TN.
AFR head question
I am thinking about going with some AFR 165's heads for my 71 302 (308 bored .040). At jegs they sell them with springs that hold up to .550" lift for a roller cam....I was going to use a flat tappet cam with 477''/.484'' inch lift. Would this cam be ok with those type springs, would they work well? I don't want to spend all that money for the heads and not be able to use the springs that come with them.
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good choice.....
thats a lot of spring for that cam......run what the cam manufacture suggest
if you are going to run them, don't brake the cam in with them, use stock type springs or if they are double just use the outers.
thats a lot of spring for that cam......run what the cam manufacture suggest
if you are going to run them, don't brake the cam in with them, use stock type springs or if they are double just use the outers.
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From: Kiefer, Northeastern Okla
You need to use springs that are matched to the cam you're using. That cam sounds like the Comp XE256H. Tyically, roller springs have higher seat and open pressures than a hyd. flat, to control a lifter that has less friction, and the roller cams typically have a more aggressive ramp profile. Excessive spring pressures are a waste of horsepower and can cause premature lifter and lobe wear. That .550 lift is a pretty vague number. I think what they mean is for the quoted price, they'll supply a spring that will handle up to that lift.I've never bought any heads from Jeg's, but I would bet if you called and gave them your cam specs, they'll install the proper springs.
Pete
Pete
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Originally Posted by petes79f150
Excessive spring pressures are a waste of horsepower
I thought the same thing.......it don't matter how much spring pressure you have...while one is being compressed another is opening...they kinda cancel each other out.
read this on the crane or comp website....makes sense....
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From: fargo, nd
the only time you want more spring pressure is when youre revving it higher, then your lifters wont float as easy. if youre keeping the rpms down on the 302 then have some lighter springs installed... if youre trying to revv it past 5000 rpm then keep the springs they give you... itll give you better high end valvetrane stability
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From: Bristol TN.
thanks guys, so my best bet would be for the maching shop to take the inner springs out and use the outer springs only? Cause i won't be reving it to 5000 rpms very often at all.
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From: Bristol TN.
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just use the outer during cam brake in if you are going to use them.....I would keep them for a future up/grade and get the right ones for the cam.
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Originally Posted by reed1951
thanks guys, so my best bet would be for the maching shop to take the inner springs out and use the outer springs only? Cause i won't be reving it to 5000 rpms very often at all.
no just get the right springs for the cam.....
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