Very Low Vacuum (around 10in)

Very Low Vacuum (around 10in) - now low compression on one bank

I haven't really worried too much about the quality of the idle of my car, and sort of gave up and assumed "its just the way it is" for a long time now. Over the last year or so I've noticed that the brake pedal has become harder and that has lead me to notice that the vacuum at idle is lower than it used to be (its gone from about 13-14 at 800 rpm to about 10).

Its pretty steady at this level, I don't really seem to have any problems throughout the rpm range. I have advanced the initial timing as far as possible without pinging. I've played with the carb to get maximum vaccum but still havent made much progress. There are no vacuum leaks that I can determine.

When I crimp the PCV line while the engine is running there is an RPM (and also corresponding vacuum level) drop, and I can hear the valve click.

What sort of thing should I look at next? Compression? Valve timing? Stretched timing chain?

Thanks.

I have removed all the lines and tested with no vacuum accessories at all. I've checked the timing and its running at 14deg initial.

I've done a compression test now and it is a bit low on the left (drivers) bank with one noticably low cyclinder.

Transmission
150 ------- 130
145 ------- 130
145 ------- 110 (135 with wet test)
140 ------- 135
Front of car

I've done a leak down test on number 1 (good) and number 6 (bad) @40 psi. Number 1 showed about 40% leakage which was just in the good range. Number 6 showed 70% leakage which was just in the moderate range, almost on the high side.

When testing the number 6 cycl, I could feel air coming out of the PCV breather hole.

I guess this means the rings in number 6 are shot

Also I noticed the balancer was off a few degrees as the TDC mark did not reflect TDC on the number 1 cycl. Number 6 had the TDC mark facing 180 away from the timing pointer.