Manifold Vacuum Experiment

Exactly. I didn't WANT high cylinder pressure numbers in a TRUCK motor. lol

As I said, I revisited the idea with the slant 6 in Vixen. I got the new balancer today and installed it and quickly realized BOTH timing marks on it were wrong, so I had to remark it. <rolls eyes>. Anyway, after doing that, I ran a compression test. I got a nes compression gauge since the last timeI did a test on this, primarily because I was thinking the numbers I got last time were ridiculously high and I was right. Rather than the 175 plus I got across the board with the old gauge, with the new one I got right at 150 on all six. So that's actually a good thing, because I believe manifold vacuum will help here too and it seems to be. It idles cleaner just like the truck. It's much less cold natured. Has about 23 initial and with the advance on manifold vacuum has right at 40. AS SOON AS the throttle is opened, it loses manifold vacuum and you can see the timing drop out. Then as you keep slowly revving it, you can see the mechanical advance come in. I'll drive it tomorrow and see how it does. My only worry is, with so much advance at part throttle and a really lumpy cam (250@ .050 on a 108) and manual transmission that it will tend to "buck" at part throttle, but we'll see.


Yup, I have no doubt it helped. MVA certainly has a place.