Mechanical Rocker Arm Ratios...

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rbdart

rbdart

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Since I've been gathering a few items to stuff in the 4-4-0 for the Dart,I have amassed a few x-tra things along the way so I could have a few choices for the final decision in the end combo which leads to one of my questions of many but I will address this one 1st...mechanical adjustable rockers actual ratios...I am sure there is a way for an average guy to figure the true ratio for himself so let er rip on the hows and not hows of accomplishing it...as a question was raised about Cranes versus Isky,Mopar and others being iron or alum or stainless steel,I myself have a 2 sets of iron Iskys 1.5's and a set of Kmj Perf stainless steel rollers 1.6's with the ball and ball style pushrod....so what are your thoughts and any tech material supporting the pros and cons of diff brands and their actual ratios versus stock or aftermarket rollers, mechanical adjustables,and which brand you deem good or bad,which you find more reliable whether it be the adjusters and nut to the roller part of it or type of bushings/needle bearings or whatever I want to hear about your experiences and thoughts and actual usage,guess we need to include the shafts pros and cons along with the hardware....thanks and keep it MOPAR
 
Easy way to find out. Mock it up,use a dial indicator. I personally like the iron rockers,( factory mechanical adjustable's) for street use. My two cents. Sorry ,I couldn't help more.Hopefully, others chime in.Good to see you working on it.
 
Are ya interested in selling one of the 1.5 iron sets?
 
the single best thing you can do for any adjustable rocker arm that's shaft mounted and has no roller bearings is banana groove the shafts. I'm using a set of Harlan sharps that have to be at least 30 years old. they for the most part operated solid flat tappet cams but I have them in my supercharged motor and the spring pressure on the seat is 360psi and they never have any issues. so with that being said I feel they are one of the best arms on the market. I've never had any rocker arms other than 1.5's so I can't say anything about the other ratios but you could only conclude that with more ratio the cam would make more power. stock rocker have the ratio all over the place and most of the time it's a lot less than 1.5 and have no place in a performance build especially with the way the prices have come down. if you use rockers with roller bearings that ride on the shaft the shaft needs to be harden so the bearings don't eat it up.
 
Easy to check for accuracy. Mock it all up and check the lift at the valve with a dial indicator, then subtract the lash. I've checked stock, Isky, Erson and Crane like that through the years and they were all pretty much right on top of their advertised ratio. I saw somewhere recently someone here said the ratios on the Isky and Ersons were lower. I've checked them myself several times and found that not to be the case. Maybe I was doin something wrong.
 
a 1.6 ratio over 1.5 would give more valve lift say like 20,iron rockers are great for the street and would be less breakable if adjusted correctly
 
Abodybomber said:
Easy way to find out. Mock it up,use a dial indicator. I personally like the iron rockers,( factory mechanical adjustable's) for street use. My two cents. Sorry ,I couldn't help more.Hopefully, others chime in.Good to see you working on it.
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Hey man,your pm box was full....lol...yes I am aware how its done but alot of people dont know or understand the mechanics of it so I thought I'd put this out there to get some feedback and pros and cons...anyone got pics of banana grove shafts they could post for reference/example? Yea I will prob end up using the old faithful irons even after buying the SS 1.6's brand new due to clearance issues but depends on what the pistons have to say after the flycuts which still isnt done....
 
I'm building a 383/432 for street use as we speak. Need super reliable for road trips and heard good things about Crane iron rockers. Have 1.76 ratio iron rockers on my work truck, Ford 428 with 20k miles on them no issues, and yes I just inspected them. For the Mopar BB bought the 1.6 ratio new at a good price. Rocker ratio on engine mock up is 1.63-1.64. Rocker to valve tip contact needs .06 lash cap when using Ferrea valves, OEM 906 iron heads. Contact sweep pattern is good using 8.0 inch pushrod length.
Pushrod angle to rocker adjuster is very good with pushrod centerline pointing slightly toward rocker arm shaft with valve closed, then centerline points slightly away from rocker adjuster Centerline at valve max open; moderate .530 lift.
 
rbdart said:
Hey man,your pm box was full....lol...yes I am aware how its done but alot of people dont know or understand the mechanics of it so I thought I'd put this out there to get some feedback and pros and cons...anyone got pics of banana grove shafts they could post for reference/example? Yea I will prob end up using the old faithful irons even after buying the SS 1.6's brand new due to clearance issues but depends on what the pistons have to say after the flycuts which still isnt done....
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Not real hard,stole this off the /6 website(the picture).My machinist,done this with stock shafts,on a low buck hydraulic cammed LA. Worked great ,with stock 273 rockers. I can do some hunting,at his shop. Depends on your patience .
 

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