Rocker ratios
Posting Guru
Joined: Aug 1999
Posts: 1,485
Likes: 3
Rocker ratios
Harland Sharp makes a 1.8 rocker that will fit BBFords (its made for BBC). Any comments, pro or con, on using these verses the 1.73. I plan to use Comp Cams #34-228-4, .467 I - .484 E lift.
Thanks
Nathan
Thanks
Nathan
Tuned
Joined: Feb 2000
Posts: 309
Likes: 0
From: michigan
Rocker ratios
well one thing i read on these ratios a while back is you can use just the 1.8 ratios for just the exhaust valves in combination with the 1.73's forthe intake valves. sounds kinda funky doesn't it. the reason for usingthe 1.8's on the exhaust is since big block fords have problems with breathing, these 1.8 ratios can open the valves if i can remember right longer and open them up alittle farther in the chambers so they can let the gases scavenge and let it breathe alittle better. it takes some machine work to get this to work. i'll see if i can rummage around and dig an old article up but i can't make any promises i've got tons of old car mags. C.J. ...
Elder User
Joined: Jan 2000
Posts: 966
Likes: 2
From: Crooked River Ranch, OR
Rocker ratios
According to "Crane Cams" master catologue "increasing the lift makes the engine think it has a larger cam ( 2-4 more degrees duration)". The problem you may encounter is "mechanical interferance" such as spring coil bind (you need to maintain a minimum of .060" free travel at full lift)or you may have to purchase different push rod lengths to get the rocker geometry back to were it should be.
CJ is correct in saying that most people generally increase rocker ratios on the exhaust side...but recently reading some tech notes from "Lunati Cams" suggested that for all out HP most engines make more HP with a single duration camshaft...of course most of us live in the "real world" of needing torque and HP over a broad range, and that's were the split duration camshaft proves its worth.
Deen Hylton
Ford F250 460 C-6, K&N, Headers, Dual Exh.,Comp. Cams,Shift Kit
Pioneer CD w/Bose Speakers.
Other Passion: Blown 77 Corvette (Sorry Guys/Gals)
How I can afford to Drive the above: 93 GEO Metro
CJ is correct in saying that most people generally increase rocker ratios on the exhaust side...but recently reading some tech notes from "Lunati Cams" suggested that for all out HP most engines make more HP with a single duration camshaft...of course most of us live in the "real world" of needing torque and HP over a broad range, and that's were the split duration camshaft proves its worth.
Deen Hylton
Ford F250 460 C-6, K&N, Headers, Dual Exh.,Comp. Cams,Shift Kit
Pioneer CD w/Bose Speakers.
Other Passion: Blown 77 Corvette (Sorry Guys/Gals)
How I can afford to Drive the above: 93 GEO Metro
Thread
Thread Starter
Forum
Replies
Last Post
