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Roller Rockers?
https://slantsix.org/forum/viewtopic.php?t=15474		 Page 1 of 2
Author:  mcm95403 [ Thu Dec 22, 2005 9:15 am ]
Post subject:  Roller Rockers?
Has anyone figured out an interchange to make roller rockers a practical swap? I know there is someone out there who makes them for the slant, but I can't seem to find the company.

Thanks,
Marc
www.marcmedina.com
Author:  zedpapa [ Thu Dec 22, 2005 9:48 am ]
Post subject:  Rockers
cox brothers makes a set but i don't know how much they are. i don't see why someone hasn't come up with a way to swap in rockers from a v8. the rockers have no offset. i don't see why it would be that hard to make a conversion shaft to mount the rockers on.

zedpapa
Author:  james longhurst [ Thu Dec 22, 2005 9:59 am ]
Post subject: 
i think the problem is the length of the rockers. most v-8 arms are relatively short. i think dave mueller used a set of big block shivy rockers on his slant, but i'm not sure what went into making them fit.
i have a set i got from the cox boys and they are very nice. i'm pretty sure they were made by rocker arm specialist. if the cox's have none in stock, it may be worth doing a group buy from the source.

-james
Author:  dakight [ Thu Dec 22, 2005 11:37 am ]
Post subject: 
I've been kind of wondering the same thing. Are the rockers from Cox the stock ratio? Is there any way to put longer ratio rockers on a slant? My thinking is probably not because of the way they are mounted but I don't really know for sure. You'd have to shorten the pushrod side and I don't know how much clearance there is in the head and lifter galley. On the late model Magnum engines with the stud mounted rockers, 1.7 ratio rockers are considered the way to go unless you're going to put in a fatter cam.
Author:  Slantenstein [ Thu Dec 22, 2005 1:18 pm ]
Post subject: 
I have a set of 1.5:1 roller rockers from Cox Bros. Jim Cox also sells 1.6:1 ratios as well. I've not had any problems with the 1.5:1 rollers rockers . Great guys to work with too.
Author:  ryandcovalt [ Thu Dec 22, 2005 2:26 pm ]
Post subject: 
What is an approximate cost on a set of roller rockers from the cox brothers???
Author:  Dart270 [ Thu Dec 22, 2005 2:44 pm ]
Post subject: 
Ryan,

I think they're about $450 shipped now.

Lou
Author:  dakight [ Thu Dec 22, 2005 3:41 pm ]
Post subject: 
Quote:
I think they're about $450 shipped now.
Ouch... pricey little buggers! Last I looked I could get a set for my 5.2 Magnum for around $300.00. I guess I'll stick with stock for now and just put in a cam. With the kind of driving I expect to do I doubt that the rollers would make that much difference anyway.
Author:  slantzilla [ Thu Dec 22, 2005 3:50 pm ]
Post subject: 
Quote:
Ouch... pricey little buggers! Last I looked I could get a set for my 5.2 Magnum for around $300.00. I guess I'll stick with stock for now and just put in a cam. With the kind of driving I expect to do I doubt that the rollers would make that much difference anyway.
You may have a point there. I ran my 12.00@110 with a set of RAS rebuilt stockers on board. :D

I do have a set of 1.6's from the Cox boys. I will try them next season. I had them on this year when I was running all motor. Results were inconclusive. :shock:

They are sweet pieces though. :twisted:
Author:  Walter Lee Jackson [ Thu Dec 22, 2005 5:14 pm ]
Post subject:  Roller Rockers?
Try Rocker Arm Specialist
19841 Hirsch Court
Anderson, CA 96007
Tel (530) 378-1075

1(800)747-2767
fax (530) 378-1177

http://www.rockerarms.com/

--Walt Jackson
Author:  dakight [ Thu Dec 22, 2005 6:49 pm ]
Post subject: 
I don't know if the same logic applies to a slant, though I don't know why it wouldn't, but the advice I hear most regarding rockers for a Magnum V8 is do either high ratio rockers or a fatter cam, but not both. It probably depends to some extent on how "fat" the proposed cam is but given the relative cost I'll opt for the cam anyway. Of course, stock ratio roller rockers would work with any cam profile.
Author:  james longhurst [ Fri Dec 23, 2005 8:57 am ]
Post subject: 
my roller rockers are from cox and 1.6 ratio. they were over 400 bucks but very nice. i swapped them in when a stock rocker broke. i was saving them for "THE" motor, but figured what the hell.
the switch to 1.6 ratio rockers will boost the valve lift without really affecting the duration. you can check it by dividing lift by 1.5, then multiply that number by 1.6 to get the new lift.
when i swapped them onto my 170 i didn't really notice any change in idle quality with the .460" 268 duration cam, nor do i have any dragstrip numbers to mark any evidence of performance gain (it was still a pig.) you chould definitely consider what ratio you'll run when choosing a cam. i'm sure there is some sort of downside to running the 1.6 ratio (valve guide wear, rocker to valvetip alignment) but i haven't run into any problems.

-james
Author:  dakight [ Fri Dec 23, 2005 11:13 am ]
Post subject: 
Actually they do increase duration because, not only do the valves open wider, but they open sooner and close later. Everything about the valve timing is exagerated by the higher ratio rockers.

At least that's what I've read; I haven't taken time to analyze the geomety of what's going on.
Author:  dakight [ Fri Dec 23, 2005 11:41 am ]
Post subject: 
OK, here's what it looks like to me from looking at the geometry. the actual points at which the vlaves BEGIN to open and at which they are COMPLETELY closed will not be changed by high ratio rockers. What does happen is that at every point along the profile of the cam the amount that the valve is open will be greater so the commonly used .050 lift point will occur sooner on the up stroke and later on the down stroke, effectively increasing duration at the .050 benchmark.
Author:  Slant6Ram [ Sun Dec 25, 2005 9:17 am ]
Post subject:  Talked to Jim Cox about rockers
I spoke with Jim this week and wished him a merry christmas. Amoung other topics, we talked about increasing rocker ratios. I forget the price.

While he supports the product that he sells, he warned that it was no magic bullet. Jim's important comment was that I could put all the cam/ rockers that I want, but unless I am increasing the compression, I would not really see the gains I am hoping for. I was hoping that 1.7 ratio rockers would make for big gains in an otherwise stock motor, but Jim believes that this is not a correct assumption.

I hated being told that I was wrong, but better now than after I spend a bunch of time and money doing custom fabrication for the 1.7 rockers.

YES! it is possible by making the rocker shaft smaller and offsetting the shaft twards the pushrods, you could potentially create rocker ratios which are far greater than the stock valve guides and spings could handle. I had it all figured out, DAmn!
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