RB26powered74zcar Posted November 26, 2005 Share Posted November 26, 2005 I once bought the cam kit from msa, and had this same thing happen to me. If you look at the contact patch on the rocker in the first post, you will see that it is WAY toward the pivot.... Not many machinest know to check EVERY valve for correct lash.. I think thats what caused this. If it were spring bind, wouldn't it have done this on all of them? Quote Link to comment Share on other sites More sharing options...
dapiper Posted November 26, 2005 Share Posted November 26, 2005 Nismo makes retainers for 43 mm spring height, so you don't have to machine the spring pockets and Isky makes the springs that provide 110 lb on seat and 260 lb at lift for these retainers. Quote Link to comment Share on other sites More sharing options...
katman Posted November 27, 2005 Share Posted November 27, 2005 Improper metallurgy, improper geometry, internally oiled versus externally oiled cam, all good possibilities. IMHO this is usually a combo of all of these in conjunction with way too high seat pressures. And way too high seat pressures is usually a crutch for cam designers that can't get rid of valve train harmonics caused by their lack of R&D on specific applications. How many cam designers are really spending any time on L series Datsuns??? 99% of the "performance" cams out there for Z's are copies of copies of very early 70's profiles. It's been estimated that it takes 75hp to drive a stock L24 cam at 5000 rpm. Imagine how much hp it takes to drive a Schneider with big ole springs! I don't remember what the lift was on Mr. Coffey's Sunbelt cam but the spring seat pressure was LESS than stock. 306+ N/A East Coast hp. Now THAT's a cam! Quote Link to comment Share on other sites More sharing options...
Silent Posted November 27, 2005 Author Share Posted November 27, 2005 i plan on running modded 50 mm su's when it's all said and done. right now, they are modded, but not 50 mm. hence why i was leaning towards the .460 lift cam. because i really don't need to spin the motor over 6500. this is more or less what im leaning towards, not sure why, the msa .495 lift cam seems peachy to me too, it's one of those things "while im in there" granted it might be too much cam for the car now, but later on, ill have the cam and not have to spend another 600 bucks to do it again. .460 lift, or .495 lift? speeder, at what point do the valve stem seals becaome the problem? Quote Link to comment Share on other sites More sharing options...
v80z Posted November 28, 2005 Share Posted November 28, 2005 If you are looking for some cheap replacement parts: First of all. Whenever installing a new cam you must use new rockers due to the interaction between the two surfaces. That being said If you are looking for some cheap replacement parts: If you need some extra rockers springs cam etc let me know. I will weigh up what I got and send it to you for the shipping. That is if you are just trying to get it running. I got a stock cam, used, but obviously much better than any other thing I have seen. Has a high nickel content. I also have a schneider, I think aboout a .420 cam used. PLenty of old rockers spings hats locks spider cages etc. and what have ya. Lash pads of varying sizes. Got out ouf the L28s when I hooked up with hybrid. Let me know. I have run into so many good deals from the people hear I gotta "Pay it forward" some. I wiped a cam once. I thought I understood the geometry issue. I installed a higher lift cam. Thought the next set of lashpads I had were sufficient. I was able to get a good wipe pattern on all rockers but I did this by adjusting the rocker arm posts. so even though I had a good wipe the angle of attck of the cam lobe to the rocker pad was too extreme and put too much stress on the rocker. In qualifying I actualy had the pad come off the rocker and bounce around inside the valve cover while the can contiued to mill the soft ductile portion of the rocker thus infusing my oiling system with plenty of metal. So we dumped the oil and filter. Grabbed a spare "used" rocker . Slammed it together and went out to win a race the next day. It held together till the end but I was counting the laps for sure. But what are you gonna do when you have invested in a race weekend. You do what you can to finish. Ok that was a bit of a rant. Sorry Quote Link to comment Share on other sites More sharing options...
Pyro Posted November 28, 2005 Share Posted November 28, 2005 CWC marking is a new core and is not as good as the factory metal. I have a CWC and it is trying to do the same thing on one lobe. And I checked each wipe pattern and used the proper thichness lash pad. And I used the proper springs and retainers. And I broke in the cam corectly. I only used the new CWC core because it was for a turbo engine and I needed the extra lobe seperation than is only possible with a blank core. I think the best and cheapest way to do a cam swap is to have a factory cam reground (this is what I did on my NA L28). Go to the junk yard and pull a stock cam and rockers. Then have Delta Cams regrind the cam to whatever specs you what and resurface the stock nissan rockers for 100.00. And Courtesy Nissan sells thicher lash pads for 3.00/each. Summit racing sells L28 crane springs and retainers for 110.00. I perfer to run my lashpads just a little thicker to move the wipe pattern more to the valve side of the rocker pad in order to reduce the valve train noise. Reduces the slop at the valve/lash pad interface. A 260/260 cam with 0.440" makes a nice improvement over a stock cam. Pulls hard to 5500 rpms and will make "useable" power to 6000 in first and second gear (with the proper springs). The stock cam seems to die somewhere between 4500 and 5000 rpms. Also, the 260/260 will not affect vacuum accessories too much (vents and brakes). There will be a slightly lopey idle with a 260/260 cam and power will be better than stock from 2500 rpms and up. Good for stock gearing, stock compression, stock exhaust, and a good daily driver cam with good mpg. I like it. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted November 28, 2005 Share Posted November 28, 2005 I am running a regrind as well from American Cams. This is the third cam from them that I've run, and all my friends run them too, and nobody has ever lost a lobe that I'm aware of. Cheap too... I'd go .495. Right now I'm running a .490/280. Started with a smaller cam and SU's, similar to the .460. Soon realized I should have gone bigger. Went to the .490 and that was a good match for the carbs. That combo worked much better than the smaller cam. Put triples on and built a new higher compression shortblock, now I'm looking for bigger on the cam again. When you're looking for cams everyone tells you "Don't go too big, you'll lose driveability, it'll suck in traffic" etc. I drove my car with triples, .490 cam, 8.3:1 compression 2.5" exhaust, heavy clutch and light flywheel in stop and go traffic daily. I loved it, the car was fast, and I never had a problem with stalling or driveability. Quote Link to comment Share on other sites More sharing options...
Pyro Posted November 28, 2005 Share Posted November 28, 2005 Yes, with carbs. go to a bigger cam, at least a 280 degree cam. The stock efi doesn't do so well when the cam gets over 270 degrees. That is why I only use a 260 degree. Years ago, I ran a 290/0.500" cam with SU's on a L28 in a 240. That car was very quick and easy to drive on the street. Quote Link to comment Share on other sites More sharing options...
Silent Posted November 28, 2005 Author Share Posted November 28, 2005 has anyone told ya, you guys kick ***? thanks so much for the info. so with the .495 cam i won't have issues with anything. IE the msa cam kit. v80z, i have spare comlete heads, so the spare cam, springs, rockers, pads, blah blah i have. but thank you for the offer!. my main concern is i want it NOT to do this again. i know there isn't a 100% against it not happening again, but with matched parts its less likely Quote Link to comment Share on other sites More sharing options...
JMortensen Posted November 28, 2005 Share Posted November 28, 2005 You will need the shorter valve stem seals, so search for that thread, the author was speeder. You'll also need aftermarket springs and retainers, since the stock springs bind at about .470 or so lift. Schneider springs and retainers will work and they don't have excessive seat pressure. Those springs with the Ford valve stems seals will get you what you need. Then you just have to play with the lash pads. Quote Link to comment Share on other sites More sharing options...
Pyro Posted November 28, 2005 Share Posted November 28, 2005 I wouldn't use another msa cam. That CWC core is prone to go flat. Get your factory cam reground to the spec you want. 280/280 with 0.480" lift or 290/290 with 0.495" lift and get the stock rockers resurfaced. Plus the msa cam kit is very expensive (450.00), doing it with crane springs/retainers, regrind cam and rockers, and courtesy nissan lashpads will be about 250.00. Even if the stock springs stacked at one inch lift it wouldn't help you. You need stiffer springs. Summit racing sells crane springs and retainers for 110.00. Plus the retainers give the springs room for another 0.100" of lift and the lash pad hole is deeper for the use of thicker lashpads. A regrind 280 degree cam will need about 0.190" to 0.200" thick lash pads and a 290 cam will need about 0.200" to 0.210" thick lash pads. But you need to check the wipe pattern on each lobe. Quote Link to comment Share on other sites More sharing options...
Silent Posted November 28, 2005 Author Share Posted November 28, 2005 kick ***. one last question, i promise. on the screwed cam thats in the car, is there a way to tell what cam it is? without having it sent off to see? any markings anywhere i should look for? the front of the cam, rear of it? Quote Link to comment Share on other sites More sharing options...
Pyro Posted November 28, 2005 Share Posted November 28, 2005 Measure the valve lift on a good lobe. Should give you a good idea which msa cam it is. Or measure the smallest distance accross one lobe then subtract it from the biggest distance accross the lobe (at the peak). The difference is the lift at the lobe. Then mulitply by 1.5 to get the lift at the valve. Do you have a digital caliper? Quote Link to comment Share on other sites More sharing options...
speeder Posted November 28, 2005 Share Posted November 28, 2005 http://forums.hybridz.org/showthread.php?t=90825&highlight=Improved+Valve+Stem+seals Quote Link to comment Share on other sites More sharing options...
(goldfish) Posted November 30, 2005 Share Posted November 30, 2005 With all this talk about cams wearing out and the new blanks not holding up. Does anybody know about heat treating/ hardening the new cams? Quote Link to comment Share on other sites More sharing options...
z-ya Posted November 30, 2005 Share Posted November 30, 2005 Who regrinds Nissan OEM rockers? My machinist won't do it, and new ones are over $30 each from Courtesy. Pete Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted December 1, 2005 Share Posted December 1, 2005 Who regrinds Nissan OEM rockers? My machinist won't do it, and new ones are over $30 each from Courtesy. http://www.deltacam.com/ Quote Link to comment Share on other sites More sharing options...
z-ya Posted December 1, 2005 Share Posted December 1, 2005 Thanks! Quote Link to comment Share on other sites More sharing options...
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