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Old 08-03-2012, 11:38 AM
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valve springs

Hi,
Just bought my aftermarket heads which have valve springs already installed,they are 20lb stiffer than my others,will it hurt my flat tappet cam?
Thanks

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Old 08-03-2012, 12:13 PM
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your cam manufacturer will have a tech line.you also need to check for bind.They will explain everything for your application.
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Old 08-03-2012, 04:53 PM
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I'm a skeptic..... and for good reason. I don't trust anybody when it comes to aftermarket engine parts. Take your heads to a good machine shop and have the springs tested for psi at the proper spring heigth and coil bind. THEN you will know and the small cost will be well worth the price of your peace of mind.
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Old 08-05-2012, 01:00 AM
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Thanks, Im still waiting for compcams to email me back! If the springs are as described I wonder if 20lbs would make any difference?
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Old 08-05-2012, 09:30 AM
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You would only know if it wiped your cam. My Edelbrock heads were 120/320 which is about normal, now if you add the 20 (or more) onto the 320 and had questionable oil, no additive or anything out of whack you might have a problem. This is why some guys recommend using old worn out springs or the special light weight springs to break in a cam.......up to you.
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Old 08-05-2012, 09:37 AM
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Thanks for that! My cam has already done 2,000 miles,im just upgrading to aluminium heads,dont really want to strip down the new heads and swap springs if the new springs would work ok.
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Old 08-05-2012, 09:41 AM
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You won't hurt it. A flat tappet cam from Comp that has say, 212/218 duration and valve lift of .450/.460" isn't made from any different steel than a cam with 240/248 duration and .550/.560" lift. 20lbs is negligible on a spring. You might see a variation on old springs close to that.
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Old 08-05-2012, 09:45 AM
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Thats great! I did think that as well but its nice to have a second opinion,will swap heads now,thanks for the info!
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Old 08-05-2012, 02:00 PM
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The springs are 20lbs stiffer on the new heads, I assume you are referring to the spring rate and not the closed/seat pressure. This should not be a big deal.

However, you need to find out the current valve spring installed height on the new heads to ensure you are at the proper seat (closed) pressure. And if you are going to do that, you might as well use the old/correct springs from the old heads.

I am not made out of money, and since flat tappet cams are so finicky with today's crappy oils, I would rather use the correct springs and not risk wiping the cam lobes.
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Old 08-05-2012, 02:20 PM
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The seat pressure on the new springs are 5lbs stiffer,and 23lbs stiffer open pressure,does this sound ok?
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Old 08-05-2012, 02:25 PM
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I think you will be OK.
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