Date registered: Aug 2005
Vehicle: 1972 250C, Ducati ST
Location: Norfolk, Virginia
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Quoted: 0 Post(s)
Vacuum at idle for healthy M130 engine?
I asked this question before and haven't gotten any responses, but I may have been asking too many questions in one post.
What should the manifold vacuum reading be for a healthy M130 (2.8L SOHC) engine? My engine is running pretty well, but I'm only getting 15" of vacuum at idle, which seems low to me.
The vacuum reading is rock-steady, so I don't think I have any burnt or sticking valves. I'm basically looking for a little better fuel economy, and I think the low vacuum might be caused by not having enough initial ignition timing. Right now, it's set at 7 degrees BTDC, with the vacuum advance hose connected. I need to check tomorrow to see if the vacuum advance is connected to ported vacuum or manifold vacuum. I guess it's probably too much to hope that the mechanic accidentally plumbed the vacuum advance to a manifold vacuum port by mistake :)
If 15" at idle is normal, then I'll look at making other changes, like opening the plug gap a little bit. The engine has dual Weber 32/36 carbs, and a Mallory electronic ignition, so I don't know how useful the stock ignition timing numbers and spark plug gap settings are going to be for my engine.
Any tips would be appreciated,