mobythevan Posted February 3, 2003 Share Posted February 3, 2003 Ok, I have seen people throw out a rule of thumb that a solid camshaft has about 8 degrees less duration because of lash. Is this 8 degree guess based on .030 lash? I am trying to make a closer guess at the (real) duration of a 282 solid cam that has lash setting of .012. This will give me a closer calculation for dynamic compression ratio. Quote Link to comment Share on other sites More sharing options...
Mike C Posted February 3, 2003 Share Posted February 3, 2003 The Vizard cam & valvetrain book uses the 280H, 282S, and 280SR as comparison cams. What he said about the 280SR was that it had the idle of a 275 hydraulic and the power of a 285. Figure the 282 has slightly longer advertised at a smaller lash figure (.020 for the 280SR) and using 278-280 advertised should get you real close, say 279. Book is very interesting reading, and I have recommended the 282S as a better choice than the 280H, but if you believe his dyno numbers, the only gains come at the extreme ends of the dyno scale. The 110 deg lobe center also hurts power output but improves the idle. My new favorite street cam is the Isky 280 Megacam with 280/280 232/232 .485/.485 on 108 LC. Use 1.6 rockers only on the intake for max power output. Quote Link to comment Share on other sites More sharing options...
Mudge Posted February 3, 2003 Share Posted February 3, 2003 Moby, if you are using Engine Analyzer or such, you can try to estimate by looking at the vacuum numbers it pulls. Most cam MFGs for cars, list either seat to seat, or .050 numbers, some bike guys use .040 or something? Anywho, the solid cam thing, they sometimes use a slower opening ramp to help with spring life, since solid cams are hard on springs. Generally you'll be doing valve lash every 5k-10k miles, and replacing them probably once a year if you play it safe, I've heard of 2 years though (dont know the mileage though either). Are you going to run oil restrictors? A solid cam is so tempting, but I really dont know that I'd want to take that step. A generic rule of thumb I've heard is that a solid will idle like a hydraulic cam 10º (.050) smaller but make power like 10º larger. Quote Link to comment Share on other sites More sharing options...
Mudge Posted February 3, 2003 Share Posted February 3, 2003 Originally posted by mobythevan:Can you make a generalization that 110 will idle between 700-900, 108 at ?? to ??, etc.? All of the cams I am looking at are in the 270 to 280 adv duration, 235 to 245 @.050 Not really, you also need to look at the duration, which you've listed, which eventually will tell you total overlap which is what is going to bleed off cylinder pressure at low RPM. This is whats going to make that lumpy idle, aka crappy running but sounds so bad-ass. I didn't notice if you said roller or flat, but 235-245 for a solid IMO is "small time", you almost can't find solids that small, they should idle great at 900, maybe less if you wanted but I dont see a reason why. Quote Link to comment Share on other sites More sharing options...
mobythevan Posted February 3, 2003 Author Share Posted February 3, 2003 I am looking at flat tappet cams. I am trying to decide between comp cam magnum 286H hydraulic, or xtreme energy solid flat tappet XS282S. These cams both have 110 LSA. But throwing in(desktop dyno) a solid oval track cam 272TL-6 actually had a flatter torque curve between 2K and 5K, but has 106 LSA. This oval track cam is 2500-6500 cam. I just wondered if idle would be horrible for the occasional drive on the street. But since it is a relatively small race cam it may not be an issue like you say. Quote Link to comment Share on other sites More sharing options...
mobythevan Posted February 3, 2003 Author Share Posted February 3, 2003 Actually it looks like the gains are marginal between solid and hydraulic for what I give up in maintenance, so I will probably just go with the magnum 286H cam. Quote Link to comment Share on other sites More sharing options...
mobythevan Posted February 3, 2003 Author Share Posted February 3, 2003 Dammit, I meant 280H in those posts, not 286H. 280H seems to be a real good match and the dyno only shows a little more torwue up high with th solid 282 cams. Quote Link to comment Share on other sites More sharing options...
Mudge Posted February 4, 2003 Share Posted February 4, 2003 Most of solid gains are either high RPM extended use, or under the curve (low RPM), but they do make more top end power as well, its just not a huge amount. From what I can recall, a flat solid is about like a hydraulic roller in terms of performance. Quote Link to comment Share on other sites More sharing options...
Mike C Posted February 4, 2003 Share Posted February 4, 2003 The 280H and 282S made within two hp of each other. Not worth mentioning. Vizards book will lay out for you how to read the cam card and explain idle. Using that you should be able to extrapolate your combo. He recommends 107 LSA for a 350 ci motor, and say 110 for a 302 and 110 for a 406. If I had to "guess" on idle quality, I would say the narrower LSA would idle about like a 284 duration cam. That 272 cam you mention might be just the ticket. IME idle would be no worse than the 280 cam. Are you running a manual transmission? If so, all should be fine. The Nissan Power booster doesn't need much vacuum relative to some other cars. I had a 284/228@.050 .480 on 112 LSA in my 331 in my Camaro years ago, and it just never ran like I thought it should. (14.10 at 100 mph in 3500# car) it now resides in my Jimmy with a 266 210@ .050 .440 cam, and I would bet the increased low and mid range torque would put the Camaro in the high 13's now. Noted as a lesson learned, that cam was completely wrong for that motor. My buddies 331 with the 280H ran 13.30's with pretty much the same setup except 4 speed and 3.73 instead of 3000 rpm converter and 4.10s in my car. Admittedly the 280H has a little more .050 duration, but the 110 LSA worked really well in his car. Quote Link to comment Share on other sites More sharing options...
mobythevan Posted February 4, 2003 Author Share Posted February 4, 2003 Ok, I am going to have to buy Vizard's valvetrain book. Is there some feeling for how much the idle will change between a cam with 110 LC vs 108 and 106? I know that the dyno software is only somewhat accurate, but I see some really good torque curves between 2K and 5K with cams that have 106 LC. Can you make a generalization that 110 will idle between 700-900, 108 at ?? to ??, etc.? All of the cams I am looking at are in the 270 to 280 adv duration, 235 to 245 @.050 Quote Link to comment Share on other sites More sharing options...
mobythevan Posted February 4, 2003 Author Share Posted February 4, 2003 I went ahead and ordered the Vizard book on camshafts and valvetrain. It was on sale for $9 at motorbooks.com like you said. It should be interesting reading. Quote Link to comment Share on other sites More sharing options...
pparaska Posted February 4, 2003 Share Posted February 4, 2003 Solid (and hydraulic) cam lobe ramps differ alot between cam brands and "lines" (Magnum, Xtreme, etc.). Looking at the difference in the seat and .050 duration numbers (if the seat durations are measured at the same lift) can show just how fast. SOme call this "lobe intensity". The Comp Cams Xtreme mechanical series and the Crane Powermax mechanical cams seem to have similar lobe intensities, with the Crane edging out the Comp Xtreme for a few comparisons I've made of similar lift and duration cams between the two. Don't forget that LSA is in camshaft degrees, and duration is in crankshaft degrees. So adding 2 degrees of lobe separation and keeping the same lobe center angles adds 4 degrees of overlap, all else being equal. This can have a sizeable impact on intake reversion and also Dynamic Compression Ratio. Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted February 4, 2003 Share Posted February 4, 2003 this is some of the best basic cam info youll find so read this first, http://www.newcovenant.com/speedcrafter/tech/camshaft/1.htm (lessons 1-8) http://www.mercurycapri.com/technical/engine/cam/lca.html http://ctfba.tripod.com/main/technical/cams/cambasics/cambasics.htm http://ctfba.tripod.com/main/technical/cams/cambasics/GraphAttack.htm http://moparjimsgarage.virtualave.net/camvalve.html http://www.federal-mogul.com/speedpro/camshafts_speed_pro.html some good general info here look closely at the duration used for each MATCHING rpm range. ALSO KEEP IN MIND THE DCR AND OVERLAP MUST MATCH look here these are the valve timeing overlap ranges that are most likely to work correctly trucks/good mileage towing 10-35 degs overlap daily driven low rpm performance 30-55degs overlap hot street performance 50-75 degs overlap oval track racing 70-95degs overlap dragster/comp eliminator engines 90-115 degs overlap but all engines will need the correct matching dcr for those overlap figures to correctly scavage the cylinders in the rpm ranges that apply to each engines use range. http://cochise.uia.net/pkelley2/Overlap.html http://cochise.uia.net/pkelley2/DynamicCR.html read this http://www.motortecmag.com/archives/2001/jun/JUN01-01/JUN010101.html http://victorylibrary.com/mopar/cam-tech-c.htm and pay special attention to this chart Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted February 5, 2003 Share Posted February 5, 2003 BTW I HIGHLY ADVISE degreeing in your own cam after buying the tools listed below if you intend to build more than just the one engine in your (Z), degreeing in the cam is a great idea because (1) youll learn a great deal about your engine doing it! (2)even with the cost of the tool kit depreciated over only a single engine build-up, it will still cost less than most shops charge to do it for you CORRECTLY and over several engine builds its a total no-brainer that your way ahead cost wise (3) you can get the purchase price of the tools back over very little time charging a minimal fee to check/install cams CORRECTLY (4) youll prevent lots of major problems by checking and finding manufacturing errors and assembly screw-ups and a single manufacturing mistake not caught in time before starting your engine can easily cost you a whole engine (5) the dial indicator and base can be used to check other engine clearances (6) the kit comes with a video tape instructions, all the tools, degree wheel, dial indicator ETC. http://www.chevytalk.org/threads/showflat.php?Cat=&Board=UBB64&Number=298366&Forum=UBB64&Words=degree%20wheel&Match=Entire%20Phrase&Searchpage=0&Limit=25&Old=6months&Main=2981 66&Search=true#Post298366 tool kit Quote Link to comment Share on other sites More sharing options...
mobythevan Posted February 5, 2003 Author Share Posted February 5, 2003 Thanks Grumpy for the tips. The 272TL-6 comp cam looks pretty good for what I want to try on my 355. Torque looks really good in simulation so I think I will try it. If it doesn't work Like I expect then I will change over to the magnum 280H down the road. Overlap on the 272TL-6 is 62 versus 60 on the 280H. DCR is a little higher with the 272 at about 8.5 by my best estimates versus 8 with the 280H. Lobe intensity is better than the xtreme solid flat tappet cams. This will probably lead to a shorter lobe life. It is also a dual pattern cam. The 272 gives about 30lb/ft torque over the 280H all the way from 2000rpm to 5000rpm. Of course this is all simulation and may fly right out the window. So I will just have to try it and see. Dyno2000 is showing approx 445Hp at 6000rpm and 450lb/ft at 4500 rpm. Of course I will only be winding it tight on rare occasion. It also shows about 370lb/ft at 2000rpm. We shall see...... BTW, I would go roller cam but I'll have to see if I have the extra money when the time comes, because if I had the extra money for that I would do 383 kit and if I had the extra money for that I would add....... Quote Link to comment Share on other sites More sharing options...
mobythevan Posted February 13, 2003 Author Share Posted February 13, 2003 I thought I better reply to this now that I have read some of Vizard's camshaft book. He lays out the things that can fool a person when looking at solid cams, and I think I was fooled by every one of them. Definitely makes hydraulic look better for me since I have no emotional connection to adjusting my valve lash. He does show how tighter LSA performs better, but really gets hurt by restrictive exhaust. After my reading I am left trying to decide between Comp Magnum 280H 110LSA, Xtreme 274H 110LSA, or the isky cam you mention 280H with 108LSA. Looks like if a guy knew exhaust flow would be good(whatever that means) then he would chose the isky cam with tighter LSA. On the other hand if you knew exhaust may be restrictive then you might want the dual pattern xtreme cam. Its easy enough to swap cams between hydraulic types so I may end up trying a few before settling on one. If I do try several cams I will dyno all and put results on my website, but don't expect this to happen very soon. On down the road..... Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted February 13, 2003 Share Posted February 13, 2003 I am running a Crane 280/288 adv. but they measure advertised at .020, is this to represent a duration closer to actual due to the lash setting. Also the lash setting is .026 would it be safe to run it tighter, as this is my first solid cam so I am unsure. The LSA, is it the degrees difference at max lift (107 ATDC ILC, 117 BTDC ex) meaning I am looking at 110 LSA?? Quote Link to comment Share on other sites More sharing options...
mobythevan Posted February 13, 2003 Author Share Posted February 13, 2003 I had these same type questions and I would say this book is the best thing you can buy to get started. For $14 it brought a lot of understanding to me. www.motorbooks.com Quote Link to comment Share on other sites More sharing options...
Mike C Posted February 13, 2003 Share Posted February 13, 2003 If it were me, (and I know how easy it is to spend your money...) I would run the Isky cam. Get the 1.6 intake and 1.5 exhaust rockers. And buy the Proform version of the cam degree kit, it's only $89, versus the $129-$139 for the comp. Then instead of spending time and money swapping and testing cams, spend all of the money designing a first class exhaust. Here is my version, 1. Patriot coated header with cone for flared pipe. At least I think they will fit... http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=102154&prmenbr=361 2. A pair of 2 1/2" 90 degree mandrel bends, have flared to adpat to header. (might need some more bends to get the thing tied into...) 3. Flowmaster y-pipe, 2 1/2" into 3" 4. 3" pipe back to diff. This is where it gets interesting, and the exhasut backpressure kit I mentioned in another thread might pay off. Either use the cone reducer, 3" to 2 1/2" and two more mandrel bends and a Dynomax, Magnaflow, etc. muffler or try to go full 3" with the corresponding 3" mandrel bends, which is probably too loud. Definitely won't be able to run 14" rims, but get too big a tire and it'll be hard to turn the pipe into the muffler, which is one area the smaller pipe will really help in. If the 2 1/2" proved to be too restrictive, you would not have to get too out of hand money or labor wise to go to the 3" I was never willing to lose my spare by modifying the well. I think I (spending your money again...) would go 3" and try several different brands of mufflers to maximize both noise control and power output. Feel like I'm giving all of my good ideas away... Quote Link to comment Share on other sites More sharing options...
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