ezzzzzzz Posted January 26, 2009 Share Posted January 26, 2009 I'm going with a re-grind for my SC'd L28 project (it's the LD28 block/crank/P90 combo). Drivability is very important to me. I've had the 500 hp V8's and they're fun but not for daily driving. I've talked to Jerry at Schneider, Jon at Delta and Ron at Isky. All are recommending cams with 225 to 230 duration at .050 and .460 to .464 lift and 112 lobe separation. It isn't confirmed but I think these are assymetrical profiles. With mild boost of about 6-8 psi I hope to achieve 250 to 300 hp (that could be a dream). Back to the question at hand. Crane has a set of springs close to stock seated/open pressures. Isky are a jump up to 130 for seat/280 opened. I don't want to overload the valve train if it's not needed. Input? Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted January 26, 2009 Administrators Share Posted January 26, 2009 My $.02. NEW stock L-6 springs are not up to to the task for ANY cam beyond stock, let alone used ones. Stock springs are definitely NOT up to the task of .460"+ lift cams. Rebello sells an outer spring that works with your stock inner spring and your stock retainers that is good for their .487" lift cam which has a very aggressive lobe profile, (these aggressive profiles work the springs harder than other "off the shelf" cam profiles from manufactures such as Crane, Isky, Comp, Schnider, etc.) This Rebello spring sounds like it would be ideally suited to your cam specs especially with the little bit of boost subjected to the back side of the intake valve without robbing power from being overly stiff. Option "A" at the bottom of this page. http://www.rebelloracing.com/nissan1.htm Hope that helps, Paul Quote Link to comment Share on other sites More sharing options...
ezzzzzzz Posted January 27, 2009 Author Share Posted January 27, 2009 Thanks Paul, I had no intention of using the old springs anyway. Ron Iskendarian spoke with me this evening about the build, the vehicle usage and expectations. He suggested a particular regrind of a Nissan cam. It will be in the .480+ range. I knew stock springs would never hold up to that. New springs will come with the cam. One more step to completing a long and costly project. The LS1 conversion would have been much more effective power/cost but I love the sound of a straight 6 winding up! Quote Link to comment Share on other sites More sharing options...
Daeron Posted January 28, 2009 Share Posted January 28, 2009 subscribed, thank you, our thoughts run along about the same lines. filed away for future reference!!! Quote Link to comment Share on other sites More sharing options...
johnc Posted January 28, 2009 Share Posted January 28, 2009 As explained to me by a L6 engine builder and verified by me over the course of a couple race seasons: stock springs will last forever and stay +/- 5% of their rate if the rpms are kept at 6,750 or less. Every time you run the spring over 6,750 rpms count that as a minute (6 times per lap at WSIR). Once you get 25 hours accumulated, the springs need to be replaced. Quote Link to comment Share on other sites More sharing options...
ezzzzzzz Posted January 28, 2009 Author Share Posted January 28, 2009 Damn, John, I have a hard time keeping the checkbook balanced. I don't think I'd be inclined to keep a count of high revs counts until they reached 25 hours. I rarely see revs that high anyhow as I don't race and prefer my driver's license and low insurance rates over a bicycle or skateboard...LOL. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 28, 2009 Share Posted January 28, 2009 As explained to me by a L6 engine builder and verified by me over the course of a couple race seasons: stock springs will last forever and stay +/- 5% of their rate if the rpms are kept at 6,750 or less. Every time you run the spring over 6,750 rpms count that as a minute (6 times per lap at WSIR). Once you get 25 hours accumulated, the springs need to be replaced. I'm guessing that recommendation is for an ITS engine, correct me if I'm wrong. The problem with the stock springs is that they coil bind at about .470" or so lift, depending on how deep the valves seat in the head, how far the seats have been cut, etc. I think that if you're using a cam with more lift than stock that allowance for 25 hrs might be reduced. From my experience the Schneider valve springs do not have excessive seat pressures and are relatively cheap. I'm not a big fan of their cams, but their valve springs are just peachy. There is an interference issue with the Schneider retainers hitting the valve stem seal at lifts over about .480, but Speeder was nice enough to figure that one out for us, and there are cheap readily available Ford seals that will allow lifts probably in the .600 range without interference. http://forums.hybridz.org/showthread.php?t=90825 Quote Link to comment Share on other sites More sharing options...
thrustnut Posted March 16, 2009 Share Posted March 16, 2009 I know this thread is a little old, but this is right in line with my project and a couple questions i have. I will be installing a .460 lift cam in my 77Z and was worried I may have interference issues and need to shim. Any input would be great. I have a stock block with 82 NA flat top pistons and a P90 head. The reason behind the head was a turbo build that never happened, now im going with the Arizona Z 4bbl intake. I know the head is a little bigger (about 9cc's over the original) and im hoping the valves are gonna be up high enough to clear the pistons when full open. The other question I had was what is reusable in a cam swap, I have new rocker arms and see I will need springs, and was planning on new lash pads unless someone thinks otherwise. Lastly, has anyone used the MSA performance valve springs? they are only like 30.00 more then the Rebello outer springs for the inner and outer springs and retainers. I just want whats gonna be best for my Z, its been in build for 5 years, and as soon as the snow melts it will be on the road. Note: I will not be hard core racing, maybe a little track time and a pass or two at the strip, nothing above 6500 RPM. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 16, 2009 Share Posted March 16, 2009 The MSA valve springs are Schneider springs. I ran them with no problems. I'm not sure if the retainers come separately from the springs, but I'd get both. What to reuse is a bit of a tricky question. I have no problem with reusing the rocker arms, others think you absolutely cannot reuse the rocker arms. The lash pads will almost undoubtedly need to be changed because the cam is not stock. If you read the stickies in this forum there are threads on how to figure out what thickness lash pad you need. Low compression .460 cam with 4 barrel sounds like a pretty crappy build. You might consider changing out the head at the very least. It shouldn't be too hard to find a smaller chambered head. Quote Link to comment Share on other sites More sharing options...
NismoZ Posted June 4, 2009 Share Posted June 4, 2009 quick question for the experienced...would it be a waist of time to throw a cam in a stock l28 with full exhaust and SU carbs? If so why? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted June 4, 2009 Share Posted June 4, 2009 quick question for the experienced...would it be a waist of time to throw a cam in a stock l28 with full exhaust and SU carbs? If so why? Kinda doing this on two forums, so there will be a little repetition here. I ran a basically stock L28 with SU's and a medium sized cam for several years before I got Mikunis. .490/280 cam and SU's is a GREAT combo. When I bought the cam my friend (who actually sold it to me) was telling me how it was going to be too big, I'd have no bottom end, etc. After I installed it and took him for a ride, he immediately ordered a bigger cam for his 510. He had been running high lift short duration cams and had sold one of those to me previously, but the results were less than spectacular. Quote Link to comment Share on other sites More sharing options...
NismoZ Posted June 5, 2009 Share Posted June 5, 2009 Kinda doing this on two forums, so there will be a little repetition here. I ran a basically stock L28 with SU's and a medium sized cam for several years before I got Mikunis. .490/280 cam and SU's is a GREAT combo. When I bought the cam my friend (who actually sold it to me) was telling me how it was going to be too big, I'd have no bottom end, etc. After I installed it and took him for a ride, he immediately ordered a bigger cam for his 510. He had been running high lift short duration cams and had sold one of those to me previously, but the results were less than spectacular. Thanks Jon, with that said i guess a cam wont hurt then...what needs to be changed with a 490 lift besides springs and lash pads ? would it clear the guides and seals? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted June 5, 2009 Share Posted June 5, 2009 Springs and retainers and valve stem seals. There is a sticky in this forum about improved valve stem seals, they are Ford V6 seals, you can get them from any corner store and they're shorter and use a better material for the seal than stock. If you do those seals with Schneider springs and retainers, you should be good to go. Quote Link to comment Share on other sites More sharing options...
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