blueovalz Posted January 12, 2002 Share Posted January 12, 2002 I talking to a tech rep at a major cam manufacturer yesterday. It was suggested to me to use a milder 351 camshaft instead of their more radical 302 camshaft (equating to similar power charactoristics) for my 302 motor. His explaination was the milder valve timing of the bigger motor camshaft will "appear" to the smaller motor to be more radical cam timing. My first impression of this statement was "no way" (more acurately "masculine bovine feses"). Being it sounded like we've got some good cam knowledge in this group, I thought I'd ask for some opinions on this suggestion. Quote Link to comment Share on other sites More sharing options...
biohzrd Posted January 12, 2002 Share Posted January 12, 2002 when you run a cam that may be large in a small ci inch motor it has a more defined idle to it. i run a cam in my 400+ ci sbc that would not be streetable in a smaller motor. the bigger the motor the less the bigger cam effects its street manners. if a certain cam is big for the 302, then it would in my mind be just right for a 351. with a bigger motor you can get more vacume than the smaller if they both run the same cam. cam science is pretty in debth though. you have to have a stall,gears,induction, and exaust all working together to get the full benifits of the cam. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted January 12, 2002 Author Share Posted January 12, 2002 Very good. It appears that no smoke was being blown you-know-where. Thanks for all the comments. Quote Link to comment Share on other sites More sharing options...
Guest Tom Scala Posted January 13, 2002 Share Posted January 13, 2002 It is true that more displacement will tame a larger cam. I ran a 230I/240E @.050 cam in a 400" motor and a 455 with the same heads and similar (9.5)compression and the big motor had 2" more idle vacuum (16")and wasn't nearly as high strung as the 400. Most cam companies rate the rpm range of their off the shelf grinds for a 350 cube engine. Quote Link to comment Share on other sites More sharing options...
pparaska Posted January 13, 2002 Share Posted January 13, 2002 Yes, I've heard/read this for years - a smaller engine with the same cam will be more radical. I wonder how much of this is really just based on the stroke and the usual large rod/stroke ratio. Past threads on this board and chevytalk refer to sites the go into an engine's stroke, rod length, intake valve closing point and dynamic pressure. I have a spreadsheet on my site that does this calculation : http://members.home.net/pparaska/VvsP.xls I got the equations from: http://victorylibrary.com/mopar/cam-tech-c.htm Other than differing rod/stroke ratio and stroke between two engines, I don't know of any other parameter that would make one engine see a cam as "larger" (more radical) than another. Also, so cam catalogs (Crane?) list different cams for different sized engines in a family based on a desired power band, etc. The smaller displacement cams will tend to have less duration for the same power band listed in a category. Quote Link to comment Share on other sites More sharing options...
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