I have been thinking about buying KRC's lighting killer package but is it really that good of a deal? i was just wondering if anyone out there is runing it and how they liked it?
Lighting Killer Package
1BadRT
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Why would you buy anything from KRC if they are making such a huge mistake?Chuck said:
The answer to that is obvious. You can't even interchange all mopar rockers. I can get some very accurate measurements of the distance between the roller and push rod end of the rocker. If they are identical then I stand by my statement about the 1.6 ratio. The only other variable is the distance from a line between those two and the pivot point.
Several problems that I'm aware of are the failure to use the correct length push rods, because even adjustable rockers have their limits. The failure to use hardened rods and to use guides. Incorrect rod length can put the roller off center and cause premature valve guide wear.
If you know of something else that would change the geometery of the rocker, let me know.
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I'm not.N56629 said:
You're fixated on that single measurement, from the fulcrum to the edges. There are characteristics to heads that require different development in the rocker design - if these characteristics are not observed you may still have the proper end to fulcrum to end design, but you'll have errors in side to side rocker offset. I'm not making hyperbole here, there's an example provided below.N56629 said:
This is very true.N56629 said:
This was passed to me recently regarding the whole issue of rocker "geometry":N56629 said:
Ford rocker installation
Its not really very in depth, but there is a bit on the second page where it warns of the need to machine things at the proper angles for proper rocker install when dealing with canted valves. You have different machine angles just within the various head designs for Ford small blocks. Now think about trying to match one of those rockers with our heads. Which Comp rocker from which Ford head was used for the R/T heads?
Chuck, I'll look up the number for the rockers when I get home. Obviously they would not be for heads with canted valves otherwise the rollers would sit on the valves at an angle when place on the magnum heads.
I asked why you would buy KRC because you have a KRC 408 on your list of things to buy.
I asked why you would buy KRC because you have a KRC 408 on your list of things to buy.
Here are the Comp part numbers that I use on my truck.
1133-16
Ford 289-302-351W Hi-Tech Steel Rockers - 3/8, 1.7
4842-6
Dodge Magnum 3.9 L-8.0L Guide Plates, Flat 5/16"
4542-16
OLDSMOBILE 3/8"X5/16" STUD
This might also interest you because Crane Cams doesn't buy into everything you hear on the internet either. I heard something that makes a little more sense. Comp doesn't like the fact that they would have to tell their customers that they have to either replace or modify their valve covers. Crane doesn't seem to have any problem with it.
Basically, if you choose to buy Crane you will pay more just for the reassurance that they say Dodge after the part number.
11746-16 Chrysler-Dodge-Plymouth 92-00, "Magnum" 318 (5.2L), 360 (5.9L)Stock ratio. Must use Crane's stud conversion kit with guideplates (36655-16), and pushrods (36668-16), to convert from the stock pedestal rocker arm to this adjustable stud mount design. (Optional heat treated pushrods available, Part No. 36621-16.) Stock valve covers must be modified or spaced upward approximately3/8" to avoid interference.
RATIO: 1.6 STUD DIAMETER: 3/8"
11746-16 Ford V-8 62-00, 221-255-260-289-302-351WStock ratio and standard stud diameter. Must machine 66-00 cylinder heads and install 99156-16 3/8? rocker arm studs and 36650-1 pushrod guideplates (heat treated pushrods required), or use 36655-16 Conversion Kit (no machining required) on 77-00 pedestal mount cylinder heads for street applications.
RATIO: 1.6 STUD DIAMETER: 3/8"
1133-16
Ford 289-302-351W Hi-Tech Steel Rockers - 3/8, 1.7
4842-6
Dodge Magnum 3.9 L-8.0L Guide Plates, Flat 5/16"
4542-16
OLDSMOBILE 3/8"X5/16" STUD
This might also interest you because Crane Cams doesn't buy into everything you hear on the internet either. I heard something that makes a little more sense. Comp doesn't like the fact that they would have to tell their customers that they have to either replace or modify their valve covers. Crane doesn't seem to have any problem with it.
Basically, if you choose to buy Crane you will pay more just for the reassurance that they say Dodge after the part number.
11746-16 Chrysler-Dodge-Plymouth 92-00, "Magnum" 318 (5.2L), 360 (5.9L)Stock ratio. Must use Crane's stud conversion kit with guideplates (36655-16), and pushrods (36668-16), to convert from the stock pedestal rocker arm to this adjustable stud mount design. (Optional heat treated pushrods available, Part No. 36621-16.) Stock valve covers must be modified or spaced upward approximately3/8" to avoid interference.
RATIO: 1.6 STUD DIAMETER: 3/8"
11746-16 Ford V-8 62-00, 221-255-260-289-302-351WStock ratio and standard stud diameter. Must machine 66-00 cylinder heads and install 99156-16 3/8? rocker arm studs and 36650-1 pushrod guideplates (heat treated pushrods required), or use 36655-16 Conversion Kit (no machining required) on 77-00 pedestal mount cylinder heads for street applications.
RATIO: 1.6 STUD DIAMETER: 3/8"
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I spent a little bit of time emailing people who know more about this than I do. I managed to get some real numbers from someone who is very high up in the valvetrain business. I can't use a name without permission because I'm quoting him third-hand off a forwarded email, but lets just say he's the equivalent of Vic Edelbrock or Doug Thorley, just with valvetrain.
According to the man himself:
the 5.9 magnum rocker has a "stud to rocker tip" measurement of 1.387"
chevy rockers have 1.420"
Ford has 1.508", nearly 1/8" longer rocker from stud to rocker tip compared to Mopar
if you use those Ford rocker dimensions on a Magnum head, it will sideload the valve stem and eat guides like candy. If your rockers have that dimension, your heads are living on borrowed time.
According to him, you can try to use shorter pushrods, to fix the geometry but the roller would still sweep the valve stem tips and sideload.
You could then machine the Ford rockers to lower the trunnions and lower the overall rocker heights until centered over the valve stem tips, and then you would have to figure correct pushrod lengths again.
See the geometry I was hinting at? Valvetrain geometry is a lot more than just that ratio. From what I see, its called "geometry" because you're describing a shape defined by points at your cam axis, up the pushrod, across the rocker, and back down to your cam. You have to observe certain limits when describing that shape, so you have to "do the homework" to paraphrase you in one of your posts. Some builders do that math, some do it by feel and get it right every time, some just assemble parts and if it runs thats great.
KRC didn't do their homework, at least where these rockers are concerned. If you want my guess, they picked out a 1.6 roller rocker from Comp that eyeballed ok when they put it on the appropriate stud, and when they adjusted the lash and the motor turned over, they called it a day. You'd be better off with Mopar roller rockers.
Anyway, all this is just FYI. If the parts are working ok for you, thats all that matters, right?
According to the man himself:
the 5.9 magnum rocker has a "stud to rocker tip" measurement of 1.387"
chevy rockers have 1.420"
Ford has 1.508", nearly 1/8" longer rocker from stud to rocker tip compared to Mopar
if you use those Ford rocker dimensions on a Magnum head, it will sideload the valve stem and eat guides like candy. If your rockers have that dimension, your heads are living on borrowed time.
According to him, you can try to use shorter pushrods, to fix the geometry but the roller would still sweep the valve stem tips and sideload.
You could then machine the Ford rockers to lower the trunnions and lower the overall rocker heights until centered over the valve stem tips, and then you would have to figure correct pushrod lengths again.
See the geometry I was hinting at? Valvetrain geometry is a lot more than just that ratio. From what I see, its called "geometry" because you're describing a shape defined by points at your cam axis, up the pushrod, across the rocker, and back down to your cam. You have to observe certain limits when describing that shape, so you have to "do the homework" to paraphrase you in one of your posts. Some builders do that math, some do it by feel and get it right every time, some just assemble parts and if it runs thats great.
KRC didn't do their homework, at least where these rockers are concerned. If you want my guess, they picked out a 1.6 roller rocker from Comp that eyeballed ok when they put it on the appropriate stud, and when they adjusted the lash and the motor turned over, they called it a day. You'd be better off with Mopar roller rockers.
Anyway, all this is just FYI. If the parts are working ok for you, thats all that matters, right?
I understand what you are saying but if I accepted that at its face value then we both would have to accept the fact that Crane is either making the Ford rockers wrong or they are making the Dodge rockers wrong. As you can see they both have the same part number. Maybe you should email your friends and see if they can explain it.
The distance from fulcrum to point is also changed on the 1.7 rockers which is what I'm using. That in itself would cause the side load that you mentioned. I also believe that any side load is minimized by the roller which rolls across the stem rather than drag like a non-roller rocker.
The distance from fulcrum to point is also changed on the 1.7 rockers which is what I'm using. That in itself would cause the side load that you mentioned. I also believe that any side load is minimized by the roller which rolls across the stem rather than drag like a non-roller rocker.
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Well I'll pass that on, but give me your linked source so I can quote that and not a thread here.
Just my own guess: it looks like both are sold with the recommendation to use an adjustable stud kit, and if you don't, machining is required on the Ford heads. My guess is that the stud kit raises/lowers the trunnion to improve the angle, and you have to compensate with pushrod length. Thats only only part of the equation though - they still have the distance difference from the fulcrum.
I don't think I'll get an answer out of anyone this weekend, because anyone who might answer is at the Nationals.
Just my own guess: it looks like both are sold with the recommendation to use an adjustable stud kit, and if you don't, machining is required on the Ford heads. My guess is that the stud kit raises/lowers the trunnion to improve the angle, and you have to compensate with pushrod length. Thats only only part of the equation though - they still have the distance difference from the fulcrum.
I don't think I'll get an answer out of anyone this weekend, because anyone who might answer is at the Nationals.
The link would be www.cranecams.com I cut and pasted right from their site. The part numbers were highlighted in red.
The next time I pull my valve covers I'm going to get some dimensions.
Ask your friends about side loading. If I'm not mistaken there is only one point at which there is zero side load and that is the point where the axis of the valve is tangent to the arc of the rocker. Does that make sense?
The next time I pull my valve covers I'm going to get some dimensions.
Ask your friends about side loading. If I'm not mistaken there is only one point at which there is zero side load and that is the point where the axis of the valve is tangent to the arc of the rocker. Does that make sense?
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Well, I'm not a valvetrain engineer, but I play one on tv...N56629 said:
In an optimum geometry, thats pretty correct. With the valvetrain we're trying to convert angular velocity to linear velocity so there is going to be a tangential-to-direct change in approach no matter what.
The big deal is of course making sure that geometry is correct.
This will all be the topic of conversation come Monday when everyone gets back from the Nationals.
BTW: I'm enjoying this - you're making me think. :biggthump
Me too. It's been a long time since I've really taken a serious look. Diamler Chrysler actually has some relatively new software to analyze valvetrain geometry. Wouldn't you like to get your hands on that?Chuck said:
Some good reads and pics -
http://circletrack.com/techarticles/4635/
http://www.grapeaperacing.com/tech/valvetrain.pdf
http://www.pontiacstreetperformance.com/psp/valvetraingeom.html
http://www.compcams.com/Technical/Products/Pushrods/
http://www.mid-lift.com/INTRO-ML-BKGRND.htm
http://www.pontiacpower.com/faqs4.htm
http://www.usaimports.co.uk/Mopar_Tech_Pages/mopar_valve_geometry.htm
http://www.hotrod.com/techarticles/43418/index4.html
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so i know this is an old thread but is anyone out there running this package or a similarly set up one? i was wondering how it drove on the street and what kinda gas mileage you get. my truck is my only ride its got 113,000 miles on it and im wondering if this would be to much for my stock bottom end.
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