What vacumn are you seeing with your bigger cams?

Would 60 kpa (9 psi) be normal to achieve oem like idle?

 

I'm getting 14 mm Hg with my meter. I believe that's 2kPA roughly.

 

im at 11-12

 

I don't have kelford 272's, but I do have hks 272's. I'm idling around 10psi. Gotta tune it . Anything below 8psi and the car tries to die. Any ideas on how to raise the vacumn?

 

bump the idle rpm a bit? Mine with the kelfords (timed straight up, oem gears) idles at ~10-11 with the a/c on, maybe 13 with the ac off. I have it kick the idle speed up with the a/c on tho.

 

Adding more ignition timing should help the idle and give you more vacuum.

 

21* ignition.

 

I have Cosworth M2's and I get about 10 with the a/c on and like 5 with the a/c on but I really need a tune...

 

Oracle you're quoting an absolute pressure because that is the way your mapping is working. Some of these guys are probably quote a relative pressure (ie negative from atmospheric). So your 60kPa or 8.7 PSI absolute is -6 PSI for those with a 14.7 PSI absolute atmospheric pressure. Plus people also quote in inches of water, cm water, mmHg etc, bar rel, bar abs, all these are on various gauges or dataloggers in common use, so be careful what you're comparing as there is a lot of ambiguity here.

 

Off topic:

Thanks john.

I think I will keep the idle as it is now, seems smooth and I don't want to be chasing my tail either.

Fuel pressure Reg was set up incorrectly. Now set that correctly and also bliss. Made a huge difference in vacumn. Base reg now 3.4/5 bar.

Looking at the loads, I tweaked mivec and timing to suit my vacumn, it is now more smooth, less aggressive and no more stalling.

24* on mivec makes for a better drive, although data does not reflect this as much.

These cams are aggressive! I think the sweet spot is 5k+ rpm on these.