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| Isky L490 (L9) camshaft http://forums.ctzcc.com/viewtopic.php?f=4&t=9320 |
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| Author: | jp260z [ Wed Nov 01, 2017 3:25 pm ] |
| Post subject: | Re: Isky L490 (L9) camshaft |
Bruce thank you for your input! No need to apologise, I'm glad you commented. I am thinking you're correct. I didn't run my Z long enough before rebuilding to really know how "normal" feels. And she was pretty tired anyway so that probably wouldn't help much. But I do believe I sacrificed top end for low end power. She feels very strong around town but when I finally find a stretch to really wring it out there isn't as much power there as it feels like (more bark then bite). Great street cam for sure but it'd be nice to have more mid to upper end power. A good spot to shift seems to be right around 5.5k rpm but I believe Compcams is correct in stating the peak happens @4800 or so. What are your thoughts on a better grind? Also thank you for the link! Jay |
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| Author: | eclipsedlife [ Wed Nov 01, 2017 5:50 pm ] |
| Post subject: | Re: Isky L490 (L9) camshaft |
I've been looking over some cams here. If this was a small block chevy I would give you specs off the top of my head. I have done cams and gears and re-timed OHC cams on 4G63's and KA24DE's before. I did look at the cam card for your cam and it did have 110 lope separation and but had a 110 intake centerline. This means the exhaust timing is really retarded(late). Not sure what other people thoughts are on that fact. I would feel it should really vacuum at idle. Is the idle stable at 750 rpm? The Isky L475 looks nice. Single pattern cam duration at 0.050"lift is 222. Wouldn't go bigger than that with out trying out someone else's car. Lift wise it should be more than enough. General rule, lift should be at least 25% of your valve size. Race motors are more like 30% or if the head has been ported. I tried to crank the numbers on the Isky cam L475 and got a intake center line of 109 and lope separation of 109. It has been a hard day so don't quote me on that. That tight of a patter should have a nice sounding idle and have some rasp if you have an exhaust. I got my 260 about 4 weeks ago. I might have a custom grind done. Wouldn't be far off of that though. Maybe lower lift to not beat up the 40 year old springs. |
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| Author: | jp260z [ Wed Nov 01, 2017 8:38 pm ] |
| Post subject: | Re: Isky L490 (L9) camshaft |
Yes, it idles nicely at 750 rpm. I do remember seeing the 110 centerline but really didn't know what that meant. It's funny that you mentioned the L475 cam. I thought that looked promising too simply because of the 222@.050 duration and healthy lift specs. You got far more out of the cam specs than I did. Vinny seems very sure that the L490 is the ticket but does seem large for all around use. Might be a better choice if I hit the track also on a semi regular basis? Idk. My first priorities are getting my throttle shafts redone, recoring my heater core, and having Vinny fine tune everything in springtime. Lots more driving next year too. For your cam, I have read countless times on other Z forums that if you are planning to run a cam with comp valve springs (stockers are only safe to .460" lift) that it is a wise choice to send your Japan stamped stock cam in for regrinding (Isky preferrably) rather than having one ground on a fresh billet. The available blanks have softer metal, lower nickel they say, and will go flat under stiffer springs. Not sure if there is a treatment option to harden the new blanks after they are ground, seems to me there should be. Also resurface your rockers too, they weren't very expensive to have done. When my cam was being setup, .230" lash pads were needed to get a proper wipe pattern. Stock ones were something like .160" or so. MSA had them on backorder indefinitely. I found them at Datsun Spirit in Virginia, he stocks them in .5mm increments and shipped them right out. If you have trouble finding ones in the thickness you need I recommend him. Jay |
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| Author: | Frank T [ Wed Nov 01, 2017 9:29 pm ] |
| Post subject: | Re: Isky L490 (L9) camshaft |
Well I just learned more about Datsun cams than I ever thought I'd use. Thanks guyZ. |
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