Quote:
Yup, still comes off the base circle at the same point, but from there on, it's 1.6 times lobe lift instead of 1.5, so that gets to .050 lift sooner thus increasing @ .050 duration. As far as advertised duration goes you have to remember that different manufacturers rate adv. dur. at .006, .020 and who knows where else.
Quote:
Yup, still comes off the base circle at the same point, but from there on, it's 1.6 times lobe lift instead of 1.5, so that gets to .050 lift sooner thus increasing @ .050 duration. As far as advertised duration goes you have to remember that different manufacturers rate adv. dur. at .006, .020 and who knows where else.
Looks like I'm in for some free beers, regardless what they saw in hot rod 
Quote:
I did the math,(trig) on it and a .509 smallblock cam goes from [Email]248@.050[/Email] to 251@ .050 lift.
Quote:
Seems that people say that changing to a higher rocker ratio increases cam duration with the lift, like 4 degrees from 1.5 to 1.6, I am not too sure I buy this, I can see where area under the curve will change but not duration, I'm I missing something
The way I see it is cams are measured by tappet lift, seems .050 is common, so no rocker change is going to effect this....But the end result @ the valve will see the change.... May have to go to a vote to see who is buying here Oh one more point... its a bunch of Chevy guys I am debating with, but don't let that influence your opinion 
Quote:
Hum.... This is not lookin as good as it did last night, Well the exact argument was.... going from a 1.5 ratio to 1.6 is the same as changing to a cam with 4* more duration,
Quote:
Hum.... ' I said: That is not true, its like going to a more aggressive lobe'
If its in print its gota be right, It was a Comp cam guy with the 4* thing but it was not @ .050, They just thought it was cause they just don't get it, I was thinking of splitting some hairs but I don't write for hot rod... so anything I say cant be right, plus I own a Mopar so what would I know anyway, funny thing is my 414 runs right with their 632s or I would not fit in the club to debate with these knuckle heads in the first place...Man that was long... I was thinking of throwing in the towel cause after reading some of the posts I can see that The comp cam guy is correct to a point even though I have solid ground to stand on, after reviewing some of the exact changes in lift points to duration I thought it was valid enough to give the 4* cause it could get close to .050 just need a little more rocker ratio or mess with the lash.... Plus if I don't loose every now and then they wont let me play 
then you guys will be stuck with me
You gotta love that, mike
.... Yep... never underestimate a Mopar small block ....
Quote:
In an old 'Crane' catalogue I have here it states that going from a 1.5 rocker to a 1.6 rocker the engine will get the same benefit as going to a cam with 3-4 degrees more duration. I can't remember exactly how it was worded but that was pretty much what Crane said. And the other thing is the engine doesn't know or care what duration cam it has it only 'sees' the valve opening and closing, and if it sees more lift earlier like you'd get with a better rocker ratio then its happier!
, So tonight's argument was how the big block chevy was the best V8 ever 
....I was gona try to explain the 454 had a poor rod ratio for a starter but I stopped myself .....Thank God the Ford crowd jumped in as I headed for the door.... This is proof that drinking can be a bad habit.
.... at this point I would rather swim around the planet... find a cold Fosters and talk Mopars I will find out what happened with the Ford guys Fri night, the conversation was getting kinda heated when I left 
lead to all of them getin tossed for 30 days 
Now I wont have to swim to grab a Now who was it that built the first hemi
good topic, but 340b5 please share that math on here how you go from say a 260 duration to more duration with rocker ratio. I would like to see the actual formuls. All I have seen is volume increase from the extra lift. thanks.
on this is that the motor is stupid, it doesn't know what the cam lift or durtation is, it does know how long and how far open the valves If you change the rocker ratio only(don't touch or change the cam) the motor will see the changes in valve action, it wlll make more or less power depending on which way the ratios are changed. I have seen this at the valves when changing ratio, try it sometimes I set the lash at zero and measure from .001 begining opening to .001 before closing, take your time and write the results down,net duration and net lift Change the rockers to a different ratio and do it again 
Don't be suprised if there is a vareince in results on the same set of rockers 
Quote:
you need to ask those guys when was the last time they ran big block chevs in top fuel or funny car.