Crane Ductile Iron Rocker Arm Adjusting Screw - torque?
#1669743
09/10/14 03:13 PM
09/10/14 03:13 PM
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Joined: Jan 2003
Posts: 1,770
Windsor, ON, Canada
Diplomat360
OP
top fuel
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OP
top fuel
Joined: Jan 2003
Posts: 1,770
Windsor, ON, Canada
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I'm playing around with the car before the season's all done here (mid-west). I've been running Comp Cams stainless roller rocker arms, 1.5 ratio in my 360 motor...but have had the older Crane Ductile Iron Shaft Mount Rocker Arms (part# 69771-1) in the box for quite some time now (new pieces).
The Crane pieces are 1.6 ratio, so this boils down to a difference of valve lift going from .537/.540 to .570/.576...Hughes HE3844AL hydraulic cam.
Given the conversations one sees here and there about the rocker arm ratios and the impacts these have I'm actually planning to do a somewhat 'scientific' test by doing a couple of track runs with my 1.5 rockers and immediately switching to 1.6...sort of a back-to-back compare. Rest of the motor checks out OK for this switch, so no worries about the extra lift causing problems with piston contact or spring retainer issues.
So here is what my question is about: what is everyone using as far as torque value for the rocker arm adjusting screw retaining nut?
My Comp rockers call for 30 ft-lbs...Crane does not publish any info in their install instructions and a call to their tech line netted "...just hand tighten it..." answer...LOL...maybe good enough, but I'm not comfy with that type of fudge factor, not when it comes to having one of these nuts back off and watching disaster strike.
Sooo....what have you guys been using?
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Re: Crane Ductile Iron Rocker Arm Adjusting Screw - torque?
[Re: Diplomat360]
#1669744
09/10/14 03:48 PM
09/10/14 03:48 PM
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Joined: Oct 2008
Posts: 506
Utah, USA
1964superstock
mopar
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mopar
Joined: Oct 2008
Posts: 506
Utah, USA
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"The LSM TQ-100-3 is a combination precision torque wrench and valve adjustment tool. It simplifies precision valve lash settings by properly torquing adjuster nuts every time. One tool does all "shaft" style rocker systems." "LSM Racing has the perfect way to adjust your valve lash with no fear of over-tightened or cracked rocker arm jam nuts. These LSM Racing valve lash torque wrenches have built-in 3/8 hex drives so you can change the socket to use with all "shaft" style rocker systems. LSM Racing valve lash torque wrenches are preset to 22 ft.-lbs. and come with 3/16, 5/32, and 1/8 T-handle Allen wrenches to make adjusting valves a breeze." Proper tool for the job! http://www.lsmproducts.com/tq1003.htmhttp://www.summitracing.com/parts/lsm-tq-100-3
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Re: Crane Ductile Iron Rocker Arm Adjusting Screw - torque?
[Re: B3RE]
#1669751
09/11/14 01:02 AM
09/11/14 01:02 AM
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Joined: Jan 2003
Posts: 1,770
Windsor, ON, Canada
Diplomat360
OP
top fuel
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OP
top fuel
Joined: Jan 2003
Posts: 1,770
Windsor, ON, Canada
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Quote:
It's great that you are doing back to back testing, but it's kind of an apples to oranges comparison. To have an accurate ratio test, you should have rockers of the same manufacturer and type with the only difference being the ratio...
Yes, you are right, I completely agree with you. The 1.5 rockers are roller tip, the 1.6 are ductile iron. For what it's worth the roller tip should allow much less false cam motion, namely, all other valvetrain geometry things considered and being in ideal situation the roller tip would allow the rocker to transfer most of the cam lobe motion to the valve tip. The 1.6 ratio on the other hand has no choice but to 'slide' the rocker arm shoe across the valve tip, which means some of the cam motion is potentially being lost and is not translating to actual valve lift. At the very least the overall duration on the 1.6 ratio at valve may actually be smaller then the 1.5 rocker. I'm particularly curious about this because the commonly accepted word on the 'street' is that an increase in the rocker ratio actually tends to increase the off the seat duration at the valve.
In my combo, I mostly want to know the real 'street feel' of this type of a change...in a dyno room/engine builder shop it would be nice to actually measure all these other details and really assess what this type of a change actually does to the valve motion itself. I'm sure someone out there has already done this...just haven't come across this type of a real 'back-to-back' comparison yet...
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Re: Crane Ductile Iron Rocker Arm Adjusting Screw - torque?
[Re: Diplomat360]
#1669752
09/11/14 01:10 AM
09/11/14 01:10 AM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Quote:
It's great that you are doing back to back testing, but it's kind of an apples to oranges comparison. To have an accurate ratio test, you should have rockers of the same manufacturer and type with the only difference being the ratio...
Yes, you are right, I completely agree with you. The 1.5 rockers are roller tip, the 1.6 are ductile iron. For what it's worth the roller tip should allow much less false cam motion, namely, all other valvetrain geometry things considered and being in ideal situation the roller tip would allow the rocker to transfer most of the cam lobe motion to the valve tip. The 1.6 ratio on the other hand has no choice but to 'slide' the rocker arm shoe across the valve tip, which means some of the cam motion is potentially being lost and is not translating to actual valve lift. At the very least the overall duration on the 1.6 ratio at valve may actually be smaller then the 1.5 rocker. I'm particularly curious about this because the commonly accepted word on the 'street' is that an increase in the rocker ratio actually tends to increase the off the seat duration at the valve.
In my combo, I mostly want to know the real 'street feel' of this type of a change...in a dyno room/engine builder shop it would be nice to actually measure all these other details and really assess what this type of a change actually does to the valve motion itself. I'm sure someone out there has already done this...just haven't come across this type of a real 'back-to-back' comparison yet...
More of what he was saying is KNOWING what the TRUE
ratio is going in... if you were to measure both
sets to get the true ratio... you can do it based
on the lift to see what you get and figure the ratio
based on that.. but you need to calculate the PR
angle in it also.. when I have done this in the past
I changed both(intake and exhaust) then I went back
and changed just the intakes.. the exhaust did nothing
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Re: Crane Ductile Iron Rocker Arm Adjusting Screw - torque?
[Re: MR_P_BODY]
#1669753
09/11/14 03:17 PM
09/11/14 03:17 PM
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Joined: Jan 2003
Posts: 1,770
Windsor, ON, Canada
Diplomat360
OP
top fuel
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OP
top fuel
Joined: Jan 2003
Posts: 1,770
Windsor, ON, Canada
|
Quote:
...More of what he was saying is KNOWING what the TRUE ratio is going in... if you were to measure both sets to get the true ratio... you can do it based on the lift to see what you get and figure the ratio based on that...
Thank you...I missed that...got my head a little too focused on measuring the impact at the valve tip instead. Yeah, I will try to measure the actual ratio for both rocker arms...given the hydraulic cam setup though I'm probably not going to be able to repeat this on each valve cycle...the lifter plunger will collapse and there is no way for me to guarantee that the collapse is by the very same amount on both tests.
OK, in the end, the numbers may tell a better story...LOL!
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