Guest windpower Posted July 14, 2004 Share Posted July 14, 2004 I've seen these on eBay for Civics and the such. Are these just a gimic? I know it would be harder to adjust such a cam gear on a Z, but could there be any advantage to them? It seems like if the cam gear could adjust itself dynamicly and not just be set staticly, you could overcome bad low rpm side affects of performance cams. (poor man's VVT?) I know that true VVT is most effective when you can varry intake and exhaust timing, but that isn't a choice we Z lovers have. Bottom line is I'm thinking about design projects for mechanical engineering and if it would make sense I would like to make a cam gear that adjust valve timing relative to engine rpm for the Z car and more marketable engines like the SBC. I've seen some other posts on valve timing that have been helpful but the search function doesn't seem to be working, so any help, even if you feel you've told us a thousand times, would be appriciated. Thanks In Advance, Paul Quote Link to comment Share on other sites More sharing options...
jp 280 Posted July 15, 2004 Share Posted July 15, 2004 You may want to look at how much its going to cost first, i was priced $50 US dollars for the JUN adjustable cam sprocket and im sure HKS and Tomei make them as well. Other wise good luck with your project. jeremy Quote Link to comment Share on other sites More sharing options...
Guest windpower Posted July 15, 2004 Share Posted July 15, 2004 Thanks for the encouragement. Money shouldn't be an object. We can get up to $10,000 for development, but we'd really have to make it someting worth while. The money is there, but this idea could be a hard sell to get the grant money since it is meant to improve older engine technology that exsists in today's engines in much more robust forms. Our hope would be that a market exsists within the community of vintage car enthusiasts that would economicaly justify the project. This gear would be more than something you would set and reset and look for the best setting. It would adjust itself as it rotates to retard or advance cam timing and if I understand it correctly, be able to improve output over rpm ranges that might be otherwise less than effecient due to comprimises made in the design of performance cams. I guess the part that I need help on is establishing if there is any truth to my idea that a cam that can adjust valve timing (advance or retard as the case might call for) with increased rpm's can have a positive effect on single cam engine performance? Quote Link to comment Share on other sites More sharing options...
sonomaz Posted July 15, 2004 Share Posted July 15, 2004 You should check out aftermarket Cam manufactureres web sites for basic cam timming information. Here is a URL to Crane's http://www.cranecams.com/?show=faq&id=2 In here they describe basic rpm and the effect of cam advance and retard. Paul Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted July 15, 2004 Share Posted July 15, 2004 Adjustable cam gears are much more useful for dual overhead cam engines. This is because you can can adjust the intake and exhaust sides seperately. Decent power AND torque gains can be made by retarding one and advancing the other (I believe it's advancing the intake and retarding the exhaust but I've probably got that wrong). On a single overhead cam Z, obviously you can only adjust the intake and exhaust together. An adjustable cam gear would give you some added flexibility, though you can easily adjust the cam timing without one, by just changing from the 1, 2, or 3 position on the stock cam sprocket, with the cam gear I assume you could really fine tune it instead of just those three positions. Adjusting it one way will decrease midrange torque, while increasing top end horsepower, while going the other way will obviously have the opposite effect. With a single cam there isn't really a total solution that would net you both hp AND torque, other than just ditching the stock cam altogether and coming up with specs for a new cam that would move the intake and exhaust timing. Quote Link to comment Share on other sites More sharing options...
slownrusty Posted July 16, 2004 Share Posted July 16, 2004 I picked up just over 3wheel hp by installing an HKS adj. cam gear on the exhaust side of my twin cam Toyota 4AG 20valve. I would have installed one on the intake side, but it has a unique VVT gear that runs off oil pressure and advances the intake as the rpms go and oil pressure goes up. Yasin Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted July 16, 2004 Share Posted July 16, 2004 The gains are never big from what I've seen personally... usually 5hp or less, but it's also usually over a broad range, and people do say they feel a difference in driveability... again this really only applies to twin cam engines though. Well also like I said you CAN make a bit of difference in the SOHC Z engine... you can improve top end or improve low end... you'll feel the difference. Quote Link to comment Share on other sites More sharing options...
clarkspeed Posted July 17, 2004 Share Posted July 17, 2004 Arizona Z makes one for the L6 Quote Link to comment Share on other sites More sharing options...
Guest windpower Posted July 20, 2004 Share Posted July 20, 2004 ok, I see Arizona Z car's cam, but it is just a static adjustment. Maybe I'm not describing what I'm after very well. I'm really more interested in the SBC as a canidate for this dynamicly adjustable cam gear because of its market potential amoung the bow-tie people but came here for advise because I love Z cars. I figure a 3% gain in horsepower would be enough for me to design the thing, but 3% of 300hp is a lot more to start with than 150hp typical amoung Z's. Quote Link to comment Share on other sites More sharing options...
jgkurz Posted August 5, 2004 Share Posted August 5, 2004 I'm looking into purchasing an adjustable cam gear and noticed a couple differences between the 4 manufacturers. I'm still trying to get information on the JUN unit. Personally I'd like at least 10 degrees of advance or retard capability in 1 degree increments. 1.) HKS - Nice looking (Who cares), Aluminum for light weight (Does it really matter), can be adjusted + or - 20 degrees in 2 degree increments. Cost = 112.00 http://www.2kracing.com/product_info.php/cPath/476_493/products_id/4935?osCsid=cb3615c2c0b50809b09717127588cf64 2.) ArizonaZ - High quality steel, can be adjusted + or - 4 degrees in 1 degree increments ( I'm Assuming). Dave the owner is a nice guy. Cost = 119.00 http://www.arizonazcar.com/sprock.html 3.) JUN - p/n 1006M-N001, Hard to get, I have no other information. http://www.junauto.co.jp/products/cylinderhead-part/cam-sprocket/index.html?en 4.) Nissan - p/n 13024-E4621, Nissan quality, Not nearly as pretty, Seems to be variation of original sprocket which requires chain removal to make adjustment. Adjustments are done in 3 degree increments. Cost = 120.00 http://www.courtesyparts.com/Merchant2/merchant.mvc?Screen=CTGY&Store_Code=CP&Category_Code=s30_nismo_adjustablecam Quote Link to comment Share on other sites More sharing options...
Lockjaw Posted August 6, 2004 Share Posted August 6, 2004 I have the nissan one, and it is not as user friendly as perhaps one you could adjust while its on the engine, but then I always wondered what would happen if those set screws or whatever loosened up? I think that the gear is useful for toying around with cam timing, depending on the size of your cam. I heard a rumor you could pick up some gains by retarding the stock cam about 4 degree's, but would have to check the source and see. Where it is more beneficial is in an engine with slack in the timing chain, but I guess I don't have to worry with that either, thanks to the kameri kit I have. Quote Link to comment Share on other sites More sharing options...
clarkspeed Posted August 7, 2004 Share Posted August 7, 2004 John, I bought a couple hunderd $ of stuff from Arizona and they threw in the cam sprocket at a considerable discount and free shipping with the other stuff. A surprise to me since they rarely discount so I bought one. I haven't installed it yet but it looks like it should work well. They machine out a ring gear from an existing sprocket and mate it to an aluminum pully. I don't endorse vendors, but I've never been disapointed with Arizona products or service. Quote Link to comment Share on other sites More sharing options...
Guest 81na ZX Posted August 7, 2004 Share Posted August 7, 2004 1.) HKS - ... Aluminum for light weight (Does it really matter), In theory, yes. Lowering the rotating mass is always useful. In practice I doubt it would be noticable. Well unless the nismo one is like 8lbs and the HKS one is 6oz... Quote Link to comment Share on other sites More sharing options...
TimZ Posted August 8, 2004 Share Posted August 8, 2004 If you want dynamically adjustable cam timing, I would think it would be much easier to make a replacement for the chain tensioner that could dynamically change the chain length on the drive side while maintaining tension. Take a look at Lockjaw's tensioner setup (maybe Lockjaw could post a pic to save people from seaching 8) ) and then think having the whole thing on a worm gear slider with a stepper motor... Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.