[AD removed for archives] ------------------------------------------------------------------- Testers Wanted! Take online surveys, earn Amazon vouchers. caadHvhbOyW3Na/MediaTransfer ------------------------------------------------------------------- My Racer Brown cam came with a card that showed lift and duration at 1.5 and 1.6. The 1.6 gives you a higher lift and could cause valve clearance problems on a decked block with shaved heads. But I didnt think the cam had to be designed for it, you just run it through a calculation and you can determine what the new lift is. Using a basic ratio calculation assuming you know the lift for the cam at 1.5, isn't New Lift = (Current Lift * 1.6) / 1.5 On an engine being build for Torque and Power, Assuming no clearance problems, wouldnt a 1.6 ration rocker with a higher lift allow for more CFM to flow into the chamber? Am I all wrong here? Sensible? --TOM On Wed, 13 Jul 2005 08:39:59 -0400, "Don Dulmage" <big-d@xxxxxxxxxxxx> said: > > Yes I know that trick it is often done on chevy SBs. > We will give it a whirl as well but my current belief is that the cam > was designed to take max advantage of the port design of the mopar head > and large lifters and it was designed for 1.5 rockers . > When we put 1.6s on we go a outside the cams carefully designed features > and it screws up the valve action and we lose power. I think that to use > 1.6 rockers the cam needs to be designed for them. I dont know if I said > it here before but we made a set of 1/7 s once from a set of crane iron > 1/5 adjustables (moved the adjusters inward about 30 years ago ) and the > results were not unlike the last test.(There was certainly no gain) > At the levels of cam we are running which are relatively mild compard to > a pro stock cam etc it would be no problem for the cam manufacture to > make a cam with the same figures and area under the curve with 1/5s that > would be the same as 1/6s are running on the 1/5 cams we are using > currently. It is I think though true that cam timing is a very critical > thing and bolting on a set of 1.6s often hurts more than it helps. We > will keep flogging this though to find out for sure. I know for instance > putting 1/6s on a cam like the ST-H-42 Racer brown which is a FULL ON cam > with absolutley no compromises would almost certainly ruin its > performance as it is already maxed out. and you cant go beyond that with > out messing things up. > 1/6 while they do not change the duration from actual opening and closing > do change the "effective duration" at 050 and at .200 lift. because the > valve is open more earlier and flow events are changed. Serious cam > manufacturuer give the duration at 200 " and at 050 for this reason. > Because the valve would be at the 050 or .200 lift point earlier the > duration at these points would be greater than it would with 1/5 rockers. > It takes very few degrees to make or ruin cams performance > . Anyway we will try several more combos and see if we ever get an > increase. (i AM BETTING NO) > I have yet to see anyone running through the pits saying i put on 1/6s > and dropped 2 tenths. Usually they are very quiet because they just > spent 3 or 4 hundred bucks and got nothing or an even worse result and > think they did something wrong. We often hear" it feels better" or "seem > a lot better" but if it aint on the time slip, baby , then it aint there. > However i reserve the right to say "I was wrong" should I get positive > results. This is just my current thinking today. > Don > Author of > Return to Deutschland (True Adventure) > Old Reliable (Mopar) > http://stores.ebay.ca/Don-Dulmage-Enterprises > [Non-text portions of this message have been removed] > Tom 65 Dart GT 'vert 68 Plymouth 'vert Las Vegas, NV -- http://www.fastmail.fm - Send your email first class [AD removed for archives] ------------------------------------------------------------------- Get a Free Sirius Satellite Package, don't pass on this! caadHlCbOyW3Nf/ProductTestPanel ------------------------------------------------------------------- ---- Please address private mail -- mail of interest to only one person -- directly to that person. I.e., send parts/car transactions and negotiations as well as other personal messages only to the intended recipient, not to the Clubhouse public address. This practice will protect your privacy, reduce the total volume of mail and fine tune the content signal to Mopar topic. Thanks! '62 to '65 Mopar Clubhouse Discussion Guidelines: http://www.1962to1965mopar.ornocar.org/mletiq.html. bOyW3N.