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i just got my 5.3 heads hand ported and flow benched its was around 230 cfms. they told me that they dont think they can get much more out of the heads with the stock valves. im getting a custom grind cam, the guy doing it says im lookin at .615-.625 valvelift. it that too much lift for a stock bottem end 5.3. right now i have a TBSS intake and 92mm throttle body with headers. is there a point when the cam too big for what i have.
This is a discussion you should be having with the man who is supplying your custom grind cam. The short answer is yes you most certainly can reach a point where your cam is too big for your bottom end. You can run into piston to valve clearance issues. And you cam can just be too big for your combo. Meaning it holds the valves open too long and bleeds off too much cylinder pressure at low rpm. Low cylinder pressure equals low torque. Without your entire combo and intended use no one can reccomend a certain cam or say the one you are looking at is bad. But you shouldn't have to ask us if you already have a reputable company setting You up with a custom grind.
these are stock flow numbers for a stock 5.3 head with NO work done to them: you mention 230 cfms? is that at .600 lift? im sure it is.Quote:
Originally Posted by 02chevyls1
Stock 5.3 HeadsChamber61.15 cc0.1000.2000.3000.4000.5000.5500.600Intake200 cc63128179210218221226Exhaust70 cc5493121145163168174Valve Diameter Intake1.89"Valve Diameter Exhaust1.55"
remember the top end produces the power, the bottom end is just a displacement pump, the more displacement the more your topend has the potiental to make power. also on a side note dont get caught up in flow numbers though high flow numbers are good, but theyre only as good as how much air can be pumped through them. cam lifts are irrelevent to the over all potiental to the bottom end. heres some good info on how a cam works :
http://www.auto-ware.com/combust_bytes/camspecs.html