low vacuum


Finally hooked up a vacuum gauge the other day. At tickover the vac is low and needle sits in the red, a slight increase in revs and it just about goes into the green.
The red says late ignition timing. So can I advance the ignition timing on the cam belt?
I did fit a new cambelt when I built the engine up, maybe I have not lined the marks up 100% though I thought I had. Could this produce this problem? Any help would be much appreciated.


Super Moderator
Staff member
If you move the cambelt you will shift the timing but also the cams.

I'd chedck it is in the correct position and correct if not, then see what you have.

My tired 250,000k engine runs almost 21" vacuum at idle and drops as a soon as I crack the throttle.

I seem to drive a 0" vacuum because I drive it WOT.


Well-Known Member
What is your ignition timing sitting at? Its just an engine so all the same stuff applies. Grab a timing light, put onto base timing mode and check it like we have been doing since engines were invented.


Thanks for the replies. I will use my timing light see what is says.
I did check my cam belt timing a while back as it was suspected I had it wrong, as it doesn't like ticking over when cold.
I will take my time this time and check thoroughly.


It is 9 degress BTDC on tickover, 27dgrees full advance. I marked the cams and I may have the marks slightly off. They look bang on static, but when I checked with the timing light they looked more lined up at 7 degrees BTDC.. Maybe moved when tensioner was put on?
Guess to alter I need to take it all back off as if doing a new belt again... "Groan"