Doogs Posted June 3, 2009 Report Share Posted June 3, 2009 Hi, In a few months I plan to build a mild 5k for my car. For a while I have been considering different options for my build, but had not thought about rockers much. I know of some people who build holden 6s and similar era engines, and one of the mods they do is to install roller-rockers and up the rocker ratio. This aims to have the valve accelerating off the valve seat faster, and to produce reasonable power without having to run huge lift in a street car engine (that would result in rapid wear and lack of driveability). Has anyone tried/considered altering the rocker setup in a k motor, and are there any of these parts around for such a small engine? Quote Link to comment Share on other sites More sharing options...
adke11 Posted June 3, 2009 Report Share Posted June 3, 2009 Hi, In a few months I plan to build a mild 5k for my car. For a while I have been considering different options for my build, but had not thought about rockers much. I know of some people who build holden 6s and similar era engines, and one of the mods they do is to install roller-rockers and up the rocker ratio. This aims to have the valve accelerating off the valve seat faster, and to produce reasonable power without having to run huge lift in a street car engine (that would result in rapid wear and lack of driveability). Has anyone tried/considered altering the rocker setup in a k motor, and are there any of these parts around for such a small engine? ay brother in Australia who built a site for Datsun A12-A15 when you get the information sent. I am also looking for ways to build Quote Link to comment Share on other sites More sharing options...
Doogs Posted June 11, 2009 Author Report Share Posted June 11, 2009 Anyone considered it or heard of it being done ? Quote Link to comment Share on other sites More sharing options...
Felix Posted June 11, 2009 Report Share Posted June 11, 2009 Considering you are building a "mild" 5k motor, why bother? Roller rockers are more a top end mod, so unless you plan on spending extended periods of time over 8 grand, I don't really think the cost/performance factor is very favourable. From what I've seen you are looking at $600-1000+ for roller rockers to suit a Datsun A series motor. Then you have to modify them to suit your 5k, also you'll be needing a solid lifter conversion.... Seems like an awful lot of money to spend on a mild build of a 5k motor. Quote Link to comment Share on other sites More sharing options...
philbey Posted June 11, 2009 Report Share Posted June 11, 2009 Yeh, the roller rocker thing is really aiming at the high end market where you need to try get that .5% power increase to get that competitive edge. I wouldn't worry about it with the milleaux of other useful, significant and cheaper mods available out there. A Cam grind will give you the things you desire, like faster valve acceleration and greater lift anyway, and that will cost you 100 bucks! Quote Link to comment Share on other sites More sharing options...
adke11 Posted June 13, 2009 Report Share Posted June 13, 2009 Anyone considered it or heard of it being done ? this is the place that produced the research for Datsun Yella Terra Race Rocker Systems :yes: Quote Link to comment Share on other sites More sharing options...
camerondownunder88 Posted June 14, 2009 Report Share Posted June 14, 2009 I once saw a K motor with Mini roller rockers. BUT mini run a 1.2 ratio so look into it but they can be grafted onto the motor. I briefly saw this car at a gathering in my town once he had spent a lot on it and for me I wouldn't bother with roller rockers. Even the TRD 3K/4K doesn't have roller rockers. Cameron Quote Link to comment Share on other sites More sharing options...
Doogs Posted June 14, 2009 Author Report Share Posted June 14, 2009 Thanks for the replies. I didn't realy have roller rockers in mind (due to the cost amoung other things), and yes also thought it would be overkill for this motor and its application. I was instead musing about whether you could easliy change the ratio and still run a flat tappet cam. Sorry, I probably should have specified that. I am aiming to build a mild motor, but a well thought out one (hence the questions). Thanks again, Dougal Quote Link to comment Share on other sites More sharing options...
orangeLJ Posted June 15, 2009 Report Share Posted June 15, 2009 In terms of holden sixes (as an example) without going to roller rockers there are a few options, main one is 1.65 ratio from falcons. Or you can bolt on 308 rockers (1.6 aswell) standard is 1.5 So if you can find a set of rockers that will bolt in and not upset the angle of operation, then Id go for it. Only thing to check is spring bind when fully compressed. Quote Link to comment Share on other sites More sharing options...
snot35 Posted June 15, 2009 Report Share Posted June 15, 2009 You're going to have to check a whole bunch of things to make sure it works properly, wipe pattern, spring binding etc. Why reinvent the wheel when you could just get a cam ground? For such a small engine, the higher ramp speed may only make a barely noticeable difference. I'd go for a basic port job first, there is quite a few areas in there that need obvious tidying up. That will help a whole lot with mid range as well as high end without pushing the valves out further. Quote Link to comment Share on other sites More sharing options...
Doogs Posted June 15, 2009 Author Report Share Posted June 15, 2009 Thanks orangeLJ, Thats more along the lines of what I was thinking. You're going to have to check a whole bunch of things to make sure it works properly, wipe pattern, spring binding etc. Why reinvent the wheel when you could just get a cam ground? For such a small engine, the higher ramp speed may only make a barely noticeable difference. I'd go for a basic port job first, there is quite a few areas in there that need obvious tidying up. That will help a whole lot with mid range as well as high end without pushing the valves out further. snot35, I am planning on doing a port job and cam as well as maybe bigger valves. I wanted to see if this could be done, and if parts were easily available. Being a k motor I assumed they were'nt, but I thought I may as well check. Quote Link to comment Share on other sites More sharing options...
tojo2 Posted June 15, 2009 Report Share Posted June 15, 2009 (edited) I once saw a K motor with Mini roller rockers. BUT mini run a 1.2 ratio so look into it but they can be grafted onto the motor. I briefly saw this car at a gathering in my town once he had spent a lot on it and for me I wouldn't bother with roller rockers. Even the TRD 3K/4K doesn't have roller rockers. Cameron Have heard of minis using K rockers for a budget hi lift mod. Those 1.7-1 roller tipped rockers could be worth it if they fit... anyone ever looked into this? :yes: forgot the link.. http://www.minisport.com/acatalog/Mini_Rol...ip_Rockers.html Edited June 15, 2009 by tojo2 Quote Link to comment Share on other sites More sharing options...
Felix Posted June 15, 2009 Report Share Posted June 15, 2009 Why reinvent the wheel when you could just get a cam ground? Exactly. You could get a cam reground to max out the available valve lift just short of coil bind. Cost $100-150. Quote Link to comment Share on other sites More sharing options...
Doogs Posted June 15, 2009 Author Report Share Posted June 15, 2009 Exactly. You could get a cam reground to max out the available valve lift just short of coil bind. Cost $100-150. Ok, point heard. I thought I may as well have a look at what else I could do to make this build as good as I can. Quote Link to comment Share on other sites More sharing options...
Felix Posted June 15, 2009 Report Share Posted June 15, 2009 (edited) Invest in some books by David Vizard and Graham Bell. :yes: Those guys will set you in the right direction to get the best bang for your buck. :hmm: It amazes me how easily and cheaply you can get a K motor to go with a well balanced package. Edited June 15, 2009 by Felix Quote Link to comment Share on other sites More sharing options...
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