Re: EMC 2013 470 B stroker build
[Re: RAMM]
#1518951
10/17/13 11:21 PM
10/17/13 11:21 PM
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Joined: Jul 2013
Posts: 561 USA
B3RE
mopar
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mopar
Joined: Jul 2013
Posts: 561
USA
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Sorry if this was covered, What rockers did you use for this build, and how much work was required to get them working with the head mods? Also would you expect the same/worse/better results with victors?
I used T&D shaft rockers in a 1.6/1.6 ratio. The only work required was milling the shaft stand down .030" with a 7/8" ball endmill.
This is why you had instability. How many finalists had valvetrain issues with their hydraulic lifters? I'm sure they didn't just put the roller in the center of the valve and call it good. Not trying to be a jerk, I'd like to see you do well, but if Mopar guys dont abandon the misinformation about valvetrain geometry, they will never be able to compete at the same level as the competition.i Kudos ony all the hard work on the cylinder heads, though. I like to see people thinking outside the box.
How would you address the geometry issues with Mopar's shaft system. I am all ears. Short of milling the rocker stands down and moving the shaft in 2 of the 3 axis, I do not see how it can be done. Please enlighten me so I can understand. J.Rob
Moving the shaft in 2 axes is what is needed, but you are going the wrong way. Dig up an old Mopar Muscle that has Indy Cylinder Head winning their dyno challenge. They had T&D help them correct geometry on their entry and they had to make stand spacers to stay within the rules of not milling the head. The shaft has to go up, not down when you use a roller rocker. The pivot centerline is between the center of the rocker shaft and the center of the roller axle, not where the roller meets the valve tip. That is the equivalent of running a longer valve which is why the shaft has to go UP. The only reason to put the roller in the center of the valve is so the roller doesn't roll off the end of the valve from the excessive sweep that comes from incorrect geometry. With .750" lift, you should be sweeping the valve less than .050" if the geometry is correct. Check it with an indicator and I'd be interested to know just what it is.
Mike Beachel
I didn't write the rules of math nor create the laws of physics, I am just bound by them.
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Re: EMC 2013 470 B stroker build
[Re: B3RE]
#1518953
10/17/13 11:45 PM
10/17/13 11:45 PM
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Joined: Jan 2003
Posts: 15,439 Val-haul-ass... eventually
BradH
Taking time off to work on my car
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Taking time off to work on my car
Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
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Looks like what you do is use offset rocker stand spacers to more closely approximate Jim Miller's Mid-Lift Geometry design. Of course, his design applies to both the roller-tip fulcrum sweep as well as the angularity of the pushrod-to-rocker relationship.
Simply offseting & raising the shaft can only help to improve the roller tip sweep, unless you happen to be working w/ rockers where the angle of the pushrod adjustment screw is less than optimum when in the standard location. Some rockers do respond positively to that, but with others (Crane "Gold" being a good example) it just makes the adjuster screw angle at peak lift even more out of parallel w/ the pushrod than before.
I always found it interesting that Miller's approach and Jesel's were so very different, considering Jesel takes what they refer to as a "low pivot" approach to minimize rocker scrub in the high lifts where the spring loads are greatest, despite the overall scrub pattern being wider.
I'm curious how one uses offset rocker stand spacers w/o redrilling (offsetting) the bolt hole (which ICH did in the Mopar Muscle Engine Challenge entry w/ the T&D rockers mounted on spacers). Does this involve elongating the rocker shaft mounting holes to enable shifting the shaft c/l rearward? I think I've seen some Harland Sharp SBM shafts like this.
Last edited by BradH; 10/18/13 12:11 AM.
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Re: EMC 2013 470 B stroker build
[Re: RAMM]
#1518954
10/18/13 12:01 AM
10/18/13 12:01 AM
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Joined: Jan 2003
Posts: 15,439 Val-haul-ass... eventually
BradH
Taking time off to work on my car
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Taking time off to work on my car
Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
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More questions: 1. Was the engine in the same state of tune when it made 720-ish HP on your dyno as when it cranked out 750+ HP at the EMC? 2. Why the major "fat" dip in the A/F ratio down low? My first thought was that big-venturi "True 950" Holley wasn't happy under a load down there, but would have expected it to be lean, not uber-rich... 3. Do the flow #s you posted reflect the head being positioned in an "adjusted" location over the bore fixture comparable to where it was on the engine w/ the offset dowels, etc.?
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Re: EMC 2013 470 B stroker build
[Re: firefighter3931]
#1518958
10/18/13 09:04 AM
10/18/13 09:04 AM
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Joined: Feb 2006
Posts: 1,051 The Great White North
RAMM
OP
super stock
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OP
super stock
Joined: Feb 2006
Posts: 1,051
The Great White North
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Thanks Ron, I am seriously impressed with the FireCore products. I wish I could've shown what they are really capable of on our good engine. J.Rob
2009 PHR\EMC Competitor 2010 PHR\EMC Competitor 2011 PHR\EMC Competitor 2012 PHR\EMC Competitor 2013 PHR\EMC Competitor 2014 HotRod/EMC Competitor 2015 HotRod/EMC NoShow 2016 HotRod/EMC 3rd place SPEC Bigblock 2018 HotRod/EMC 7th place G3
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Re: EMC 2013 470 B stroker build
[Re: BradH]
#1518960
10/18/13 02:24 PM
10/18/13 02:24 PM
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Joined: Nov 2003
Posts: 5,160 Texas
dannysbee
master
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master
Joined: Nov 2003
Posts: 5,160
Texas
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Ramm thanks for all the pictures and information. I knew there was hp in the repositioning of the heads as a friend of mine had a challenger race car that he and another friend of mine built on a shoe string about 16 years ago. They moved the heads up on it and it ran extremely well for what it was. 440 Short block was stock down to the cast pistons. Block was zero decked. Heads were 915 mildly ported 2.14 1.81 valves. Cam 528 Mopar cam, m1 intake, 850 Holley and 1 7/8 super comps. 727,10" converter 4.10 gear. All this installed in a 70 challenger that weighed 3600 ready to run. Great weather 10.90's. Hot weather 11.teens. Pretty quick for a combo most wouldn't think would get out of the 12's. With the new Cnc block machining centers can't you re position the bores? If you could move the bores down in the block .020-.025 then move the head .120 that would be substantial. For the guys that need the head stock but would like a better valve angle would you angle mill the block?
Getting old just means you were smarter than some and luckier than others.
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Re: EMC 2013 470 B stroker build
[Re: BradH]
#1518962
10/18/13 11:04 PM
10/18/13 11:04 PM
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Joined: Jul 2013
Posts: 561 USA
B3RE
mopar
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mopar
Joined: Jul 2013
Posts: 561
USA
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Quote:
Looks like what you do is use offset rocker stand spacers to more closely approximate Jim Miller's Mid-Lift Geometry design. Of course, his design applies to both the roller-tip fulcrum sweep as well as the angularity of the pushrod-to-rocker relationship.
Simply offseting & raising the shaft can only help to improve the roller tip sweep, unless you happen to be working w/ rockers where the angle of the pushrod adjustment screw is less than optimum when in the standard location. Some rockers do respond positively to that, but with others (Crane "Gold" being a good example) it just makes the adjuster screw angle at peak lift even more out of parallel w/ the pushrod than before.
I always found it interesting that Miller's approach and Jesel's were so very different, considering Jesel takes what they refer to as a "low pivot" approach to minimize rocker scrub in the high lifts where the spring loads are greatest, despite the overall scrub pattern being wider.
I'm curious how one uses offset rocker stand spacers w/o redrilling (offsetting) the bolt hole (which ICH did in the Mopar Muscle Engine Challenge entry w/ the T&D rockers mounted on spacers). Does this involve elongating the rocker shaft mounting holes to enable shifting the shaft c/l rearward? I think I've seen some Harland Sharp SBM shafts like this.
Points well taken BradH, but a allow me to make my case.
First, while Miller's approach does address both the valve and pushrod side of the rocker, you are at the mercy of the manufacturer you choose when buying rocker arms. That adjuster angle is near impossible to correct once designed into the rocker and machined accordingly. But, having the valve side of the equation correct is far more important and beneficial to the performance and longevity of the valvetrain. Plus, having the valve side correct will allow for less spring pressure and not having to use "special lifters" that are unheard of in the world of the competition (chevy, ford etc.). I'm not saying the pushrod side isn't important, but it doesn't compare to the valve side. BTW, I have a set of SB Crane Gold's, circa 1998, on the bench right now that I checked the adjuster angle on a CMM and they were only out by 2 degrees. I've had them off by ten degrees or more.
Jesels low pivot approach is a mystery to me if not completely counter-intuitive. That low approach means the valve opens more slowly than it would with Miller's advice, and accelerates as it gets closer to full lift. I don't know about you, but my cylinder heads always flow more air at .500-.600 lift than they do at .200-.300 so I want to get it there as quickly as possible (think "fast cam lobes"). Then the valve does not decelerate as it should at full lift and now the valve becomes very difficult to control (more spring). At best, you may gain a few thousandths at full lift from the reduced sweep on that end, but you have given up way more than that all the way from the seat up to that point due to the slower acceleration down low. To me, the spring loads would be greater doing it Jesel's way just because of the need for more open pressure. Then, on the way down, the rocker moves quickly from full lift and slows once it gets to the lower lifts (harder for the valve to "keep up" and less time for the port to flow good air). From a purely logical standpoint, it doesn't sound like a good thing to me.
In most cases, I do not need to elongate the holes in an aftermarket shaft. There is usually enough wiggle room to get the offset as long as the rockers aren't commercialized. By commercialized I mean designed with a longer fulcrum length to put the roller on the center of the valve when just bolted on, so people will buy it on the premise that it has better geometry. I'm sure one brand in particular comes to mind. The shafts you speak of are made by Comp as well and they are marketed as offset shafts for more spring clearance. Funny, I don't have spring clearance issues when the shafts are raised to the proper location. Not saying I never will, just haven't so far. BTW, have you ever priced those shafts? Oh, and you would still have to offset the stands somehow.
One question, what do you consider optimum adjuster angle?
Thanks for the thought provoking conversation. I like it.
Mike Beachel
I didn't write the rules of math nor create the laws of physics, I am just bound by them.
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Re: EMC 2013 470 B stroker build
[Re: B3RE]
#1518964
10/18/13 11:42 PM
10/18/13 11:42 PM
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Joined: Nov 2003
Posts: 5,160 Texas
dannysbee
master
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master
Joined: Nov 2003
Posts: 5,160
Texas
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Thanks for bringing this subject up as I am building a max wedge engine and the heads have no rocker stands. I will be getting billet stands made and I knew there had to be a way of figuring the optimum height.
Getting old just means you were smarter than some and luckier than others.
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