Brodix RRO 270, Comp Pro Magnum Geometry Issue - Chevelle Tech
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post #1 of 48 (permalink) Old Nov 11th, 19, 11:10 AM Thread Starter
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Brodix RRO 270, Comp Pro Magnum Geometry Issue

The problem: Roller contact is ~.050"-.060" from the exhaust side of the valve tip at 90 deg to the valve stem

Here are all the specs:
Brodix RRO 270 (purchased completely assembled)
1.88 Ex Valve 5.394" over all length (Brodix pn 81038)
2.25 Int Valve 5.218" over all length (Brodix pn 81040)
Springs 165#/385# installed at 1.910" (pn BT120121)
1.50" OD steel retainers with 11/32, 10 deg locks
7/16" studs, 2.130" tall measured from the head surface

Comp Ultra Pro Magnum Roller Rockers, 1.7:1 (Comp pn 1620-16).
NOTE: The tip of the push rod cup is about .500 higher than the center line of the trunnion/roller

I watch the Foxwell video on setting up rocker arm geometry and it is very straight forward and easy to follow. I did a preliminary check on my kitchen table and discovered two problems.

1) On the intake, with the rocker at 90 deg to the valve stem, I have maybe one full turn on the lock. I cannot achieve 90 deg on the exhaust without coming off the stud.

2) At 90 deg, the roller contact pattern is (close as I can measure) between .050"-.060" from the edge of the valve tip. This was measured on the intake. The exhaust looks like it would land in the same spot. I will try to load some pictures later today.

After doing some research, I found this is not unique to me and is in fact quite common for those that actually take the time to check and set it up properly. However, what I did not find is a lot of advice on how to fix it other than custom offset trunnion from Crower or the offset custom rocker from CStraub that they developed around 2016 (?). Both are significantly more $$.

There is a very long and informative post on the 3rd Gen website about this very problem. The solution, I assume, that most people go with is using a shorter push rod to center the contact pattern and sacrificing proper geometry. This is not direction I really want to go.

Thoughts or suggestions are most appreciated.

While I really like this rocker, I will probably order one each of two other recommended brand/model rocker and see of those are any better (Crane Gold, Harland Sharp)

-Kevin
1965 Chevy Biscayne
<removed> 454cid, "peanut ports", Voodoo 60201
<coming soon> 460cid, Brodix RRO 270, 229/241 Hydraulic Roller
TH400, 3.36 Stock Rearend
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post #2 of 48 (permalink) Old Nov 11th, 19, 12:48 PM
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Re: Brodix RRO 270, Comp Pro Magnum Geometry Issue

I have AFR heads and ran into the same problem when trying to use the Comp steel rocker arms. This was in 2015 before Straub had made the custom ones that he now sells. Upon his advise I switched to Crane Golds and when I remeasured the pushrod length was much shorter, like 0.100 shorter than what I measured for the Comp rocker. I think Chris mentioned that the Comp rockers were also used on another 1.7:1 application and the rocker design had been modified to work on both, which in turn made it not fit either application well.

I don't think there are any easy solutions for your problem, selling the Comp rockers may reduce the cost for the good rockers?

Jeff Evans
65 Chevelle, LS3/T56 transplant in progress
67 Chevelle, ZZ502, AFR 305, Straub Solid Roller, 400 Turbo, Moser Rear 3.42 gear
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post #3 of 48 (permalink) Old Nov 11th, 19, 3:39 PM Thread Starter
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Re: Brodix RRO 270, Comp Pro Magnum Geometry Issue

Thanks for your input Jeff. Were you able to achieve the proper geometry with the Crane Gold rockers and obtain an acceptable contact pattern?

I have been thinking about this a lot and by shortening the push rod to center the contact pattern, I am bringing the center line between the push rod cup and the trunnion closer to 90 deg off the push rod. This would effectively lessen the amount of lift seen at the valve. If anything, it would lessen the number of degrees the rocker rotates. I want every inch of lift that I paid for here.

-Kevin
1965 Chevy Biscayne
<removed> 454cid, "peanut ports", Voodoo 60201
<coming soon> 460cid, Brodix RRO 270, 229/241 Hydraulic Roller
TH400, 3.36 Stock Rearend
65cayne is online now  
 
post #4 of 48 (permalink) Old Nov 11th, 19, 3:51 PM
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Re: Brodix RRO 270, Comp Pro Magnum Geometry Issue

You may need backset rockers. Check with Mike Lewis aka wolfplace I know he has fixed backset comp rockers changing the trunion in the past.

https://www.chevelles.com/forums/13-...-geometry.html

Or contact comp cams and see what they charge to change yours or of possible return them and order backset rockers direct from comp.
Another option if you want steel is crower backset rockers but they are more money than comp.
http://www.crower.com/media/pdf/2008b/153-155.pdf

Chevelle Malibu ss 64
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post #5 of 48 (permalink) Old Nov 11th, 19, 4:12 PM Thread Starter
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Re: Brodix RRO 270, Comp Pro Magnum Geometry Issue

Just as a side note, I did call Comp tech support and they were no help at all. I am not even sure he knew what valve train geometry meant.

-Kevin
1965 Chevy Biscayne
<removed> 454cid, "peanut ports", Voodoo 60201
<coming soon> 460cid, Brodix RRO 270, 229/241 Hydraulic Roller
TH400, 3.36 Stock Rearend
65cayne is online now  
post #6 of 48 (permalink) Old Nov 11th, 19, 4:44 PM
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Re: Brodix RRO 270, Comp Pro Magnum Geometry Issue

Kevin
In steel the Comp will work but not real well as you have found unless modified.
The only real good choice in steel is the Crower (Centerline)

The older Crane which had a shorter pivot length were the best choice out there in aluminum up until the newer ones Scott had done which are a custom Harland Sharp which are available from AFR, Chris, Mark & me & are substantially less money than the Crower
I do not know if the newer Crane are the same rocker as the old one since Comp bought them although I have my doubts as Comp has their own aluminum rocker so it seems a bit redundant to have two..........

To what you said about people fixing this by making the pattern centered & wide,,,,,,
DO NOT DO THIS IT WILL DESTROY THE GUIDES
The narrow pattern that is off center while obviously not ideal is a much better choice if you are not going to change or modify the rocker as the valve doesn't really care where the pattern is but it does care about being pushed sideways

Mike (Wolfplace)
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post #7 of 48 (permalink) Old Nov 11th, 19, 7:30 PM Thread Starter
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Re: Brodix RRO 270, Comp Pro Magnum Geometry Issue

Quote:
Originally Posted by 65cayne View Post
The problem: Roller contact is ~.050"-.060" from the exhaust side of the valve tip at 90 deg to the valve stem

Here are all the specs:
Brodix RRO 270 (purchased completely assembled)
1.88 Ex Valve 5.394" over all length (Brodix pn 81038)
2.25 Int Valve 5.218" over all length (Brodix pn 81040)
Springs 165#/385# installed at 1.910" (pn BT120121)
1.50" OD steel retainers with 11/32, 10 deg locks
7/16" studs, 2.130" tall measured from the head surface

Comp Ultra Pro Magnum Roller Rockers, 1.7:1 (Comp pn 1620-16).
NOTE: The tip of the push rod cup is about .500 higher than the center line of the trunnion/roller

I watch the Foxwell video on setting up rocker arm geometry and it is very straight forward and easy to follow. I did a preliminary check on my kitchen table and discovered two problems.

1) On the intake, with the rocker at 90 deg to the valve stem, I have maybe one full turn on the lock. I cannot achieve 90 deg on the exhaust without coming off the stud. NOTE: This was done with the valve closed (on my kitchen table). One half of .600/.570 valve lift, per the Foxwell video, would get me .300"/.285" of thread on the studs..
2) At 90 deg, the roller contact pattern is (close as I can measure) between .050"-.060" from the edge of the valve tip. This was measured on the intake. The exhaust looks like it would land in the same spot. I will try to load some pictures later today.

...

Thoughts or suggestions are most appreciated.
See edit above (I couldn't edit my original post)

-Kevin
1965 Chevy Biscayne
<removed> 454cid, "peanut ports", Voodoo 60201
<coming soon> 460cid, Brodix RRO 270, 229/241 Hydraulic Roller
TH400, 3.36 Stock Rearend
65cayne is online now  
post #8 of 48 (permalink) Old Nov 11th, 19, 8:51 PM Thread Starter
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90 deg to the valve (contact on the left edge... pic rotated on me)
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-Kevin
1965 Chevy Biscayne
<removed> 454cid, "peanut ports", Voodoo 60201
<coming soon> 460cid, Brodix RRO 270, 229/241 Hydraulic Roller
TH400, 3.36 Stock Rearend
65cayne is online now  
post #9 of 48 (permalink) Old Nov 11th, 19, 8:59 PM
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I know you don't wanna spend, but I'd go for the correct rocker. Sell the others on eBay to recoup some money, then start ur foxwell method over. I think in the end, you'll be happy you made the choice to do it right. Sleep better at night that way.
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post #10 of 48 (permalink) Old Nov 11th, 19, 9:34 PM
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Re: Brodix RRO 270, Comp Pro Magnum Geometry Issue

Quote:
Originally Posted by 65cayne View Post
90 deg to the valve (contact on the left edge... pic rotated on me)
I think you need to recheck things that looks a little extreme even for those rockers............
Are you sure you got your 90 measurement correct?
How many turns down from 90 did you go?
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post #11 of 48 (permalink) Old Nov 11th, 19, 10:28 PM Thread Starter
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Re: Brodix RRO 270, Comp Pro Magnum Geometry Issue

Quote:
Originally Posted by Wolfplace View Post
I think you need to recheck things that looks a little extreme even for those rockers............
Are you sure you got your 90 measurement correct?
How many turns down from 90 did you go?
So that picture shows the contact at 90 degrees to the valve face with the valve closed... So now I can hear you saying "Well Kevin that is not the way to do it" and you are correct.

What I thought I was demonstrating was how far the rocker would cross the valve tip as it crosses mid-lift (90 degrees) when properly set up. I just realized that since the stud is canted towards the valve, when things are properly set up that will move the contact point sufficiently back and away from the hairy edge it sets on in my photo. If I can get my engine back soon I will set it up and measure properly.

However, what still concerns me is the number of threads I will be able to engage on the stud. Unless I am misunderstanding something, if I set the rocker at 90 degrees with the valve closed, then, when properly set up, I am only going to thread the rocker down the stud a distance equal to 1/2 valve lift (ideally). That doesn't seem like much engagement. Am I off track here?

-Kevin
1965 Chevy Biscayne
<removed> 454cid, "peanut ports", Voodoo 60201
<coming soon> 460cid, Brodix RRO 270, 229/241 Hydraulic Roller
TH400, 3.36 Stock Rearend
65cayne is online now  
post #12 of 48 (permalink) Old Nov 12th, 19, 1:32 AM
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Re: Brodix RRO 270, Comp Pro Magnum Geometry Issue

Quote:
Originally Posted by 65cayne View Post
So that picture shows the contact at 90 degrees to the valve face with the valve closed... So now I can hear you saying "Well Kevin that is not the way to do it" and you are correct.

What I thought I was demonstrating was how far the rocker would cross the valve tip as it crosses mid-lift (90 degrees) when properly set up. I just realized that since the stud is canted towards the valve, when things are properly set up that will move the contact point sufficiently back and away from the hairy edge it sets on in my photo. If I can get my engine back soon I will set it up and measure properly.

However, what still concerns me is the number of threads I will be able to engage on the stud. Unless I am misunderstanding something, if I set the rocker at 90 degrees with the valve closed, then, when properly set up, I am only going to thread the rocker down the stud a distance equal to 1/2 valve lift (ideally). That doesn't seem like much engagement. Am I off track here?
Its not uncommon that you need longer rocker studs. ARP 135-7202 is maybe the stud you need. This post has massutements of several part nrs. https://www.google.se/amp/s/www.chev...t.html%3famp=1
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post #13 of 48 (permalink) Old Nov 12th, 19, 1:01 PM Thread Starter
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Quote:
Originally Posted by Malibu ss 64 View Post
It’s not uncommon that you need longer rocker studs. ARP 135-7202 is maybe the stud you need. This post has massutements of several part nr’s. https://www.google.se/amp/s/www.chev...t.html%3famp=1
Thank you for that link.

My engine is ready today so I should have the heads on it this week to see what the final story is here. Standby for updates.

-Kevin

-Kevin
1965 Chevy Biscayne
<removed> 454cid, "peanut ports", Voodoo 60201
<coming soon> 460cid, Brodix RRO 270, 229/241 Hydraulic Roller
TH400, 3.36 Stock Rearend
65cayne is online now  
post #14 of 48 (permalink) Old Nov 13th, 19, 12:44 AM
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Re: Brodix RRO 270, Comp Pro Magnum Geometry Issue

You shouldn't have an issue with stud length with this set up, something is off on your 90 degree estimation I think you'll see it when the rockers are moving in an actual ark .

I have the same heads as you, once you have them on, you will see the rockers don't center well side to side, take out the rocker studs. you will have the adjust, bend the guide plates (exhaust side in my case) to center both rockers. Re torque to 45 with loctite 271(per brodix). I didn't, when we went to check lash the studs loosened up, as I loosened the poly locks. didn't catch it until we fired it back up and I had several studs come loose on the dyno.

I used the howards endurance rockers, they are just slightly towards the outside of center so not perfect, but the sweep is very thin.


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post #15 of 48 (permalink) Old Nov 13th, 19, 10:48 AM Thread Starter
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Re: Brodix RRO 270, Comp Pro Magnum Geometry Issue

Quote:
Originally Posted by kermitsass View Post
You shouldn't have an issue with stud length with this set up, something is off on your 90 degree estimation I think you'll see it when the rockers are moving in an actual ark .

I have the same heads as you, once you have them on, you will see the rockers don't center well side to side, take out the rocker studs. you will have the adjust, bend the guide plates (exhaust side in my case) to center both rockers. Re torque to 45 with loctite 271(per brodix). I didn't, when we went to check lash the studs loosened up, as I loosened the poly locks. didn't catch it until we fired it back up and I had several studs come loose on the dyno.

I used the howards endurance rockers, they are just slightly towards the outside of center so not perfect, but the sweep is very thin.
I'll keep and eye out for that. I have four single rockers in the mail right now that I am going to try out; Harland Sharp Original, Harland Sharp Diamond, Crane Gold, and a Howards rocker.

<edit> I will add, I prefer to stay with my original choice but we'll see how it works out.

-Kevin
1965 Chevy Biscayne
<removed> 454cid, "peanut ports", Voodoo 60201
<coming soon> 460cid, Brodix RRO 270, 229/241 Hydraulic Roller
TH400, 3.36 Stock Rearend
65cayne is online now  
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