M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Engine + Driveline => Topic started by: 318is91turbo on October 07, 2013, 05:20:41 PM
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has anyone ever tried it? thinking about picking up some used cams for cheap and a micrometer. using a table grinder. and seeing what happens.
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What is going happen is you will have wasted a lot of time and energy. You want cams, buy them. Or at least let a professional grind them to your specs.
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Are you serious? You need to have the shape of each lobe be the same. There is no way you are going to be able to replicate that. Also, the shape of the profile matters A LOT. An improper shape will cause your valvetrain to self destruct. It takes a lot of math to get a correct lobe shape!
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As stated above, don't do it. Cams cost what they do because of the insane cost of the specialized equipment that cam houses must invest in, as well as the sheer number of hours that it takes to do a precision grind on a cam even with machinery developed specifically for it. Then factor in all the engineering time put into the design of the cam profile. Many times there will also need to be a tempering / hardening operation performed on them if the lobes don't meet Rockwell hardness requirements after welding. Then there is the importance of the surface finish of the slip surfaces (lobes, bearings). And of course, if you want to increase lift you will need to weld on additional material before the precision grind, which is a whole process in itself. Just getting remnant oil out of the porous cast iron prior to welding is basically out of reach for a DIY'er. If you do a DIY job, assuming that the car even really runs, chances are that you will end up destroying your lifters and maybe even breaking valve springs.
So yeah, it isn't a DIY activity by any stretch of the imagination. Leave it to the experts that have invested $millions into equipment and know-how. I spent many hours on the phone with Metric Mechanic when I was having issues with cam wear in my custom engine, and even they contract cam jobs out to the experts.
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you make it out to be some godly knowledge or seomthing. its not all that difficult if you simply understand it. measure twice grind once. i understand it. and actually might have access to a cnc lobe grinder soon. :)
and its just a extra set of cams im about to buy im trying it on. if it doesnt turn out proper i wont put them on. simple as that.
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you make it out to be some godly knowledge or seomthing. its not all that difficult if you simply understand it. measure twice grind once. i understand it. and actually might have access to a cnc lobe grinder soon. :)
and its just a extra set of cams im about to buy im trying it on. if it doesnt turn out proper i wont put them on. simple as that.
If you figure out how to do it, I have a great opportunity for you! Not in a BMW though.
The Honda 80's V4 motorcycles had really bad problems with cam wear. If you could figure out how to resurface those cams, you'd have a nice little side job regrinding scored cams & followers.
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you make it out to be some godly knowledge or seomthing. its not all that difficult if you simply understand it. measure twice grind once. i understand it. and actually might have access to a cnc lobe grinder soon. :)
and its just a extra set of cams im about to buy im trying it on. if it doesnt turn out proper i wont put them on. simple as that.
If you get it all figured out, be sure to let us know. You'd probably be able to make good money if you have those sorts of skills.
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you make it out to be some godly knowledge or seomthing. its not all that difficult if you simply understand it. measure twice grind once. i understand it. and actually might have access to a cnc lobe grinder soon. :)
and its just a extra set of cams im about to buy im trying it on. if it doesnt turn out proper i wont put them on. simple as that.
Lol. You have absolutely no idea what you are talking about.
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wazzu, you just wait good sir. you will see. and i shall charge you double if you come to me.
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Whatever ends up happening, just make sure to post some pictures. It's going to be a pretty good learning experience for you.
Folks in here aren't trying to give you a hard time. It's friendly advice. Many of us have been DIY'ing and fabbing stuff for well over a decade and, well, the reasons why we don't grind our own cams have already been plainly stated. If it was feasible to DIY it and save $1k, people would be doing it already. Anyway, if you have an extra set laying around and it didn't cost you anything then I say go for it since it won't cost you anything when you have to toss them into the scrap heap.
Anyway, what are you going for exactly in terms of the grind? What sorts of lift and duration are you targeting? What ramp rates will you be dialing in, and will those profiles be tappet-friendly? Cams for rocker arms, rollers and lifter buckets all have different profile requirements. If I knew what those were exactly, I'd tell you, but I don't.
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you make it out to be some godly knowledge or seomthing. its not all that difficult if you simply understand it. measure twice grind once. i understand it. and actually might have access to a cnc lobe grinder soon. :)
and its just a extra set of cams im about to buy im trying it on. if it doesnt turn out proper i wont put them on. simple as that.
Lol. You have absolutely no idea what you are talking about.
Shhhh. I want to see pics of the DIY process lol.
We were all at this stage at one point. "Anything's possible, there's no reason to pay some jerks that claim to have special knowledge for something I can just DIY after thinking about it for a week!" I remember back when I was ~20 and was posting about designing and DIY'ing my own wheel hubs for a 5-lug conversion. Jordan told me I was a f***ing moron and "damning others with my stupidity" haha. And he was right, it was a dumb idea! But that didn't stop me from spending a bunch of time researching the idea and coming to my own conclusion that turning my own wheel hubs was a quick way to end up dead!
As far as cams, I really had no idea how involved those were until the last year or so when I was in constant contact with Metric Mechanic about my top-end issues. Jim over at MM really hooked me up with the knowledge dump. For one, I never knew that the lobes have a slight angle on them so that they don't run perfectly parallel to the lifter, but instead cause it to rotate and distribute wear across the slip surface, without cocking it in the tray of course.
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i mean its not even that. ill make sure i post some pics. it could be a few weeks, maybe a month or two before i start this. making my grinding bench should be fun. :) theres a difference in diy'ers who think about how to do things. and then theres diy'ers who do the things they think of. im a do'er idk about you guys.
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i mean its not even that. ill make sure i post some pics. it could be a few weeks, maybe a month or two before i start this. making my grinding bench should be fun. :) theres a difference in diy'ers who think about how to do things. and then theres diy'ers who do the things they think of. im a do'er idk about you guys.
Nothing wrong with that. Just saying, the reason that people don't DIY everything isn't because they are lazy. As long as you are going into it with the intent of learning and having some fun, all's well.
Again, what are your design goals for these? Lift vs duration? How do you plan to increase those items? It's going to involve welding on the lobes, no way around it. Draw out the cam timing maps to get a good picture of your overlap targets. ANYONE can grind a cam. FEW can set the right design targets and actually execute the cleaning/welding/quenching/grinding operations. The issue here is how much power you will end up losing as a result, and whether or not the lifters will be salvageable afterward. Remember, you want to put a VERY slight angle on the running surfaces, like a few mils across the lobe width, so that they spin the lifters in place and distribute the wear. A straight grind would be a disaster. The cams may be free, but a new or rebuilt head and lifters probably isn't.
More power to you though. It's all just words of caution based on decades+ of personal experience.
PS
If you are going to weld on the cam, and I can't see any way to avoid that, you need to bathe the cams in a solvent that evaporates cleanly (acetone, MEK, xylene...NOT paint thinner) for a good few days to extract the oil out of the porous casting and then stick it in an oven for a day or two to fully evaporate the solvent. Trying to weld porous cast metal that was soaking in oil for decades is an exercise in futility. You are going to want to TIG it as well. MIG is likely to warp the cam since it heats a lot more than the work area.
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Ill just drop this on here to help explain. Grinding the lobes is the easier part. The shape of the lobes is very complex.
http://lotusproactive.files.wordpress.com/2013/08/lcvt_insert.pdf
Lots of people DIY and get significantly worse results after the "upgrade" because they have no idea what they are doing. This is one of those times :)
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We were all at this stage at one point. "Anything's possible, there's no reason to pay some jerks that claim to have special knowledge for something I can just DIY after thinking about it for a week!" I remember back when I was ~20 and was posting about designing and DIY'ing my own wheel hubs for a 5-lug conversion. Jordan told me I was a f***ing moron and "damning others with my stupidity" haha. And he was right, it was a dumb idea! But that didn't stop me from spending a bunch of time researching the idea and coming to my own conclusion that turning my own wheel hubs was a quick way to end up dead!
Interestingly enough I designed a 5 lug hub that would fit directly on the 4 lug spindle (smaller spindle diameter). I analysed the design in FEA and also had some guys in dimensional management verify my tolerances were correct for that application.
The killer is the cost of billet in that diameter! The cost to have them machined to proper specs for flatness, perpendicularity, runout, ect. Would have been too high to justify. An order of 20 sets was not enough volume to bring the cost down to something I felt had a chance of selling so the project was abandoned. I would have to have the hub shape cast and machined instead of using billet, but no way I was fronting the money for a proper mold!
A hub is not impossible to DIY, but its definitely not for the random guy on the street to attempt :)
I will be working on another attempt at a 4-5lug front hub conversion in the future though trying to get the cost reasonable!
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Yeah, one of the first things that hit me was that it was going to cost more to DIY my own than to swap in E36 parts. DIYing would have been more fun probably. At the time I was just an engineering student and only had a cursory understanding of the things you mentioned...and it quickly hit me that I shouldn't go messing with the wheels' attachment if I didn't understand everything involved. And yeah...casting ferrous material is no joke.
Good link to the Lotus brochure. If that doesn't clearly convey the message that cam design is not "just eyeball it" stuff, I don't know what will.
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I'm sure the OP thinks Lotus is a bunch of rookies :) Colin Chapman what?
The hub is hard to improve on, especially for the cost it would take to do so. The spindle on the otherhand is much easier and requires a much smaller diameter of billett! This is not a new solution, but I've never been excited about the options out there.
The E36 stuff has the wrong geometry, even with 96+ spindles and LCAs. Its fine for a street car or a static show car, not for a track car though. The specs can match statically, but dynamically the suspension has different curves.
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Hmm, did not know that. So there is really no legit-handling 5-lug swap for the e30 then?
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the lotus link is awesome. and i know its not something you can just eyeball.. and if you dont understand the theory of cam grinding... ( saying i needed to weld metal on) then you have no place even commenting in the thread. you grind the round side. the valves can self adjust that little bit you grind of.. thus making you have a higher lift on the lobe side. its a simple concept to gain power. but to do it right is gonna take time. and i understand that. and am fully prepared to spend hours probably days without a proper,, proper meaning legit 10k$ machine lol.. to measure everything as i go and make sure i dont take off too much. dont worrie guys. when it comes out good. im gonna be buying up stock m42 cams and selling regrinds for a decent price. and your 5 lug hub idea is awesome. i had been curious about this myself. cant you just retap 5 lug wholes in the existing hub? i thought that seemed fairly plausible to achieve if you made a 5lug template with the centric bore to align the holes. i feel like you could even get away with missing all the 4 lug holes. goodluck with your new 5 lug endeavor.
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RE: Hubs
The closest you could get would be to use one of the existing holes and add 4 new ones, making a 5x100 pattern. That gives you 18 degrees of separation between two of the tapped holes & existing ones, which is definitely not a whole lot. Not an idea I endorse. Building your own spindles from scratch is a better idea IMO. Who knows, maybe some existing BMW model uses the same spindle geometry and has a 5-lug pattern already in it.
RE: Cams
If you are going to grind down the base circles, you may need to look at custom lifter shims so they don't pop apart. Since you are a DIY kind of guy, you can in fact turn out custom spring seats and other parts on a lathe and send them for case hardening. The ones in my valve train were done exactly as such. How much max lift can you run before you hit coil binding issues? Beyond spring issues...how much higher can the lifter bodies sit before their oiling grooves no longer align with the oil galley holes in the cam trays? Meaning, the lifters get starved for oil when the lifter is in its rest position. Then, and this bit me in the ass, you have to look at how the increased lift on the nose of the cam is going to travel up the leading edge of the lifter. Too much lift on flat tappets and you get what happened to me (linked pic). You must run oil with high ZDDP, and MM's oil life tests concluded that only Castrol 10W-60 TWS and Mobil 1 15W-50 provide any sort of adequate protection.
http://bmw.e30tuner.com/images/my318is/pic/deadspring/int_c1.jpg
If your proposition is that you are taking so little off of the base circle that it won't affect anything else, then I can't even see why you are bothering with this. Every micron off of the base is a micron added to max lift, and you won't be able to reshape the nose much to increase duration unless you take a fair amount off of the base. "Cam grinding theory" goes well beyond "grind down the base circle to buy lift and more room for duration."
Welding to change the profile is perfectly acceptable as a practice and often employed in situations where the customer isn't planning to build a custom valve train (as well as in systems where they are). It means that the extra hardening / tempering step is needed, which isn't the case when reducing the base circle, but it's a trade-off.
Believe me, you are far from the first guy that has come through the forums intending to reinvent the cam modding industry. Wanting to do it to have some fun and learn is one thing, and totally fine. Claiming that you are going to out-do established cam companies and sell a superior product before even getting a single DIY-cam running is just silly. I hope you prove us wrong, really, it would be an epic DIY enthusiast moment. I won't believe it until I see it though.
I gotta ask again...what lift and duration are you targeting? Get some data going in here. It isn't exactly going to be a trade secret. MM publishes pretty reasonable details about the grinds for their Sport and Rally M42 engines. What re-shaping of the powerband are you going for? How far can you lift on the stock springs before the coils bind? Planning to dyno the car with stock cams and the modded ones?
Here's a pretty slick mod that you should look into while you have the cams out, BTW.
http://www.youtube.com/watch?v=ynVBlDMow3k
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BTW...ever get that turbo rig up and running? Megasquirt? How about those AFM mods?
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soon. soon my little grasshoppers. your like a bunch of impatient obnoxious highschoolers balling on mommy and daddy. i cant just snap my fingers and bam. waiting to get in a stable living enviroment. i am to move soon and dont want to set shit up just to move it again. im lazy. but give me a few months.
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Regarding cam grinding:
If you are on this forum asking how, do not attempt. LOL
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lol. thanks colin. im not asking how tho. i didnt get a chance to pick up the cams so it could be a while. im gonna attempt it on some gokart engines i have first lol.. grind the cams and weld the tappets and grind down to adjust valve lash to proper spec. might pocket the flat top head on the kart engine to allow higher lift. max it out.