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I just put some Ford rockers on my intakes, can someone tell me how much duration and lift I will gain? I dont have time to measure push rod travel and hope to gain some bottom end to carry a heavy barge. I know my exhaust clearance is 110 so I wont mess with them. Geometry looks good and they are Crower steel rockers. Thanks
Take the lobe lift of the cam and multiply it by the rocker arm ratio:
Example .450" x 1.7 = 760 ish .450 x 1.73 = 770 ish
Personally, I don't think that small a ratio and lift change will net you any gain you will notice, but good luck.
I just put some Ford rockers on my intakes, can someone tell me how much duration and lift I will gain? I dont have time to measure push rod travel and hope to gain some bottom end to carry a heavy barge. I know my exhaust clearance is 110 so I wont mess with them. Geometry looks good and they are Crower steel rockers. Thanks
If you're putting Ford rockers on a BB Chev, they may look like they will work, and they go up and down like they're supposed to, but the geometry is wrong. Hold the Ford and Chev rocker along side eachother, and look at the difference between the angle of the pushrod pad. The extra friction you'll induce with poor geometry will most likely offset any gains you'll see with more lift and area (if any)
Bad Geometry=Big Problems. .0 Vs.3=no gains...
If this comes from your experience, thanks very much. I have heard nothing but the opposite up here in hillbilly land. I have my old cranes with me to change back at Moses Lake.
Take your lift at valve and divide by 1.7 to get lobe lift. Take that # and then times by 1.73
Say your cam has .500" valve lift with 1.7 ratio, you'll only have .509" with a 1.73 ratio.
If you have a .700" valve lift cam with 1.7, you'll only have .712" with the 1.73 rockers.
The change in .006, .050, .100, and .200 duration values will be near nothing too.
BTW: What if your Crane's have 1.72 ? LOL.
Keep what you have and what is made for the motor your running.
BTW: Spokane area has a lot of serious hp running around. There are many up there that know their schit.
FWIW, when I built my 467, I measured the lobe to confirm the grind, and it was right on. I also measured actual valve lift at the retainer, and my Crane Gold 1.7 (stamped on them) rockers actually provided a ratio of 1.73 according to the actual gross lift.
CJ, I have a set of Crane gold 1.8s......Pay the shipping and I'll let you try them just to see if it makes any difference.....Ray 805 300 0012