whats the biggest cam i can go and still pass emmissions? i have the sniffer test and look for cats!! im runnin a 212-218 now but i would like to go bigger.......i want a good lope to it!!!

 

Cam size goes as far as the tuning goes.

As far as the cam itself, the heads have their limits before the emissions holds it back.

Don'y pick a cam for it's sound, your asking for trouble.

 

ok so your sayin it depends on how ood of a tunner you are as to what size cam you can run and still pass emmissions? i was just wondering if there was like a standerd cam that most people with a pritty good tune can still pass emmissions. i would like to have like a 118-124 or so...but i have to pass!!

 

Something like that. There is a point when no amount of tuning will get you through emissions, though.

That's where the factory limits come into play. Unmodified heads have lift issues at about .480." That's the generally accepted limitation before you start worrying about clearances between the retainers and the guide bosses and saftey margins and whatnot.

You'll probably hit the physical limits before the tuning limits.

 

You can get a cam with less than .480" lift with way too much overlap.

TPI has issues, primarily at idle, when overlap is too great and LSA too little. The good news is SD is tuneable. The bad new is you must tune.

 

I don't recall the number off the top of my head. You'll have to search for it. But there is a hard number for degrees of overlap on an SBC that will guarantee failure for CA emissions. You can probably calculate a general ballpark, if you look at the cams that pass and the ones that won't. If you pass CA smog, you'll pass smog tests everywhere.

The information is on the net somewhere, you'll probably have to google it. I *think* it's something like 4* of negative overlap @ 0.050" is what's required at the minimum. The more negative, the better the chances. That number is a recollection, but don't count on that without some research of your own.