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Author Topic:   bumpstick questions
racing33A
Dirt Forum Racer

Total posts: 97
posted October 18, 2005 02:29 PM  
Is it better to run a smaller cam in the .450 to .500 lift as opposed to say a .530 to .542. This is on a 3/8, high banked track, rochester 2bbl, stock intake, any iron (straight plug) head. I ask because I just read that most stock cast iron heads are flowing all they can by about .450 lift. Is that right? Right now I use the midwest#8. If a stock head in fact is flowing all it can by .450 then why would I need to put all that extra stress on a valvetrain by lifting to .542????? Why are solid lifter cams preferred over hydraulic cams? Do I need to make a cam change? The more I try to figure it out the more confused I get.
Thanks for the help
racing33A

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racing33A
Dirt Forum Racer

Total posts: 97
posted October 19, 2005 06:25 AM  
I can not believe that a forum of opinionated people have no comment. I could really use the help of someone who is cam smart. Anyone??

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TEAMPCR
Dirt Freak

Total posts: 238
posted October 19, 2005 07:14 AM  
Key word here is "MOST" stock intakes. It will all depend on which intake you have. I ran the same set-up that you have last year. I had a 4412, stock 2-bbl intake, 441 heads and headers. It would go to about 7300 rpm and had excellent low end with the #8 cam. Going with the split profile cam that favors the exhaust side definitely improves flow, in my opinion. Dave

leapinlizard
Dirt Freak

Total posts: 402
posted October 19, 2005 07:25 AM  
If your heads run out of breath at .450, There's no use of lifting the valve higher. It just wears out part's faster.

leapinlizard
Dirt Freak

Total posts: 402
posted October 19, 2005 07:27 AM  
Solid cam's benefit the racer by preventing the lifter from over filling with oil and holding the valves open.

dgb
Dirt Full Roller

Total posts: 70
posted October 19, 2005 12:31 PM  
you are right that most stock cast heads won't gain much, if anything above .450, but remember that that advertized cam lift number just occurs at one moment in the intake stroke, and the rest of the time is obviously at some lift below it. I'd say you should think about it in terms of maximizing the duration at or above that .450 So .450 for a MAX lift is going to work against you, but that does not mean you have to go hog wild, you're right, it's hard on valvetrain parts. Somewhere in between would be optimum. Quick ramp rates, without excessive lift is the ticket IMO. Call a reputable cam grinder. On restricted engines with stock heads, you can definately get over-cammed in a hurry. Let the real experts help you.

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