Bearwen Posted June 9, 2022 Share Posted June 9, 2022 So how many have larger cams in there L28 motors and what is your idle vacuum? Post up your build or at least your cam specs and the vacuum you pull at idle. Also what RPM do you idle at. Thought a list with cam specs and vacuum and rpm might be good info for others considering cam upgrades and what not. Just might help if you do a cam upgrade and end up with low/high vacuum or low/high idles etc you will know it's probably not normal and you have an issue somewhere. Quote Link to comment Share on other sites More sharing options...
AydinZ71 Posted June 10, 2022 Share Posted June 10, 2022 On 6/8/2022 at 9:30 PM, Bearwen said: So how many have larger cams in there L28 motors and what is your idle vacuum? Post up your build or at least your cam specs and the vacuum you pull at idle. Also what RPM do you idle at. Thought a list with cam specs and vacuum and rpm might be good info for others considering cam upgrades and what not. Just might help if you do a cam upgrade and end up with low/high vacuum or low/high idles etc you will know it's probably not normal and you have an issue somewhere. Unfortunately, I do not have such data to share but in general a lopey cam is going to hurt your idle vac., and you will need to inch-up your idle rpm. Is there a particular reason you need the vacuum? Brake booster? There are larger boosters out there, but you would need to fabricate to adapt them in most cases. Quote Link to comment Share on other sites More sharing options...
Bearwen Posted June 10, 2022 Author Share Posted June 10, 2022 (edited) I do have a .460 lift 280 duration cam from comp cams but I just thought it would be good to have a post showing different cams with different compression ratios and idles as well as vacuum so people thinking about a cam upgrade will have a general idea of what to expect from different cams. We are running stock L28 1979 280zx dished pistons and stock compression on a older ( got some miles on her so maybe 8-1 cr ) motor. stock n47 head with port work done and kept the steel exhaust inserts. A 3-2-1 header and we are using modern injectors in the stock intake driven by a megasquirt 3 X. We run a low idle 750 we pull around 8inHg really love the way it sounds at that idle (it is an issue in tuning though ). Edit: forgot to mention we are running a lightened rb25 flywheel and clutch ( using the Godzilla works flywheel shim) Edited July 5, 2022 by Bearwen Quote Link to comment Share on other sites More sharing options...
Twerkinggodzilla Posted June 10, 2022 Share Posted June 10, 2022 I am about to do a 292 480 lift trying to find all the info tho Quote Link to comment Share on other sites More sharing options...
AydinZ71 Posted June 11, 2022 Share Posted June 11, 2022 (edited) Tuning w/ cam is tricky. It really has to be under load, and at higher RPM. RPM’s under the cam’s peak torque range will be wonky because of reversion and poor volumetric efficiency. Off-load like at idle, I tune for max vacuum and the smoothest idle I can get. Did you clock the head to the block when you installed the cam? It’s really important with wilder cams to ensure the lobes are landing exactly to the cam chart. Not just for performance, but also for off-load rev-up. With an adjustable EFI, have you considered running a small turbo? That will work with 8:1 static CR. You will have a bunch more torque without sacrificing street-ability. You already have one of the most expensive components, which is the independent EFI. With the headers and cam, I understand if you are committed to NA. Edited June 11, 2022 by AydinZ71 Quote Link to comment Share on other sites More sharing options...
Twerkinggodzilla Posted June 11, 2022 Share Posted June 11, 2022 5 hours ago, AydinZ71 said: Tuning w/ cam is tricky. It really has to be under load, and at higher RPM. RPM’s under the cam’s peak torque range will be wonky because of reversion and poor volumetric efficiency. Off-load like at idle, I tune for max vacuum and the smoothest idle I can get. Did you clock the head to the block when you installed the cam? It’s really important with wilder cams to ensure the lobes are landing exactly to the cam chart. Not just for performance, but also for off-load rev-up. With an adjustable EFI, have you considered running a small turbo? That will work with 8:1 static CR. You will have a bunch more torque without sacrificing street-ability. You already have one of the most expensive components, which is the independent EFI. With the headers and cam, I understand if you are committed to NA. Not commented to Na at all I have a turbo I was planning to install this month. And the bigger cam. Car has forged crank and rods and arp head studs. Turbo I have 16g-6-10.5 off of a evo9 that was pushing 400hp was going to passenger mount the turbo already have intercooler installed and 38mm blow off valve. From turbo smart I am really new to gas motors and trying to turbo them just nervous I guess lol Quote Link to comment Share on other sites More sharing options...
Bearwen Posted June 11, 2022 Author Share Posted June 11, 2022 (edited) I do intend to turbo it later and yes it's all clocked and good to go. the reason I made the post was so when people are considering a cam upgrade they would have a reference as to where to start with idle and what to expect with different cams sizes and different timing and compression ratios which all factor into how well it will idle at different RPMs. We idle low around 750 ( my sons car and he loves the almost stalling lope sound ( it's cool to the kids)) best idle is closer to 1,000rpm more vacuum ( not much more about 12")smoother idle less rev up off the line and works well with a lower compression motor. with the aftermarket EFI when idle if higher 1000-1100 we are able to get more vacuum and we also go down a little in the manifold pressure Kpa ( low idle speed 750 we are 75-80 Kpa and higher idle speed 1000ish we're in the 68-71 Kpa) Edited July 5, 2022 by Bearwen Quote Link to comment Share on other sites More sharing options...
AydinZ71 Posted June 12, 2022 Share Posted June 12, 2022 Cool hope you get some responses. Good luck on the car! Quote Link to comment Share on other sites More sharing options...
munters Posted June 17, 2022 Share Posted June 17, 2022 my cam is 290 with 480 lift. Vacuum is at 13. compression 10:1, forged custom pistons, stroked 280 crank, e88 head has 280z valves and is ported. videnza flywheel and tripple dcoes. idles down to 550rpm with 750rpm nice and steady. Quote Link to comment Share on other sites More sharing options...
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