Date:         Sun, 12 Aug 2001 00:59:06 EDT
Reply-To:     FrankGRUN@AOL.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Frank Grunthaner <FrankGRUN@AOL.COM>
Subject:      Re: Boston Bob Engine - Follow Up
Comments: To: ingalls_mark@hotmail.com
Content-Type: text/plain; charset="US-ASCII"

In a message dated 8/11/01 9:27:35 PM, ingalls_mark@HOTMAIL.COM writes:

<< Yes, it seems strange. When I first got my van,I checked my general auto
repair books and they all mention 16 to 18" at idle. I figured maybe my low
vacuum was because of the 1.9 liter's retarded timing.

But for the past year I have been monitoring posts that mention vacuum and
10 to 12" seems to be the norm for the 1.9 or 2.1 wasserboxer. >>

Must say that two thoughts come to mind:

1. Heavy overlap on the cam. This will give a lousy flow at idle with plenty
of residual exhaust to foul the burning of the fresh charge. High overlap
cams need resonant exhaust flow to place a low pressure node in the
combustion chamber, thereby enhancing filling and developing more power.
Probably begins to be effective around 3K rpm, maybe more like 4K. Also a
function of valve lift. This negative effect can be minimized by playing
around with ignition timing, but its only a Band-Aid. These comments are in
agreement with an earlier post.

2. The POS engine has very high frictional losses (endemic with boxer
configurations) and can barely turn over. Low vacuum says that a high load is
drawing down engine rpm at a given air/fuel ratio.  (This sometimes indicates
a high slipper load (referring to the bottom of the piston as the slipper)
because of too tight a tolerance at the base of the cylinder bore, or too
large of a piston) Taper is the usual cause I believe.

2a. All waterboxers leak (vacuum too that is).

BTW, Classic fuel-economy-in-the-toilet-with-cruise-control relates to porous
vacuum diaphragms at the actuator or control valve. This leak is often
continual, but not so bad that the cruise control doesn't work. The leak
translates in the end to poorer air/fuel ratios, and poorer precision of
control. Both effects knock the hell out of fuel economy. Comments relevant
only to vacuum operated cruise controls operating off manifold vacuum. I use
an electrically (stepping motor) articulated cruise control.

Still sounds wrong to me!

Frank Grunthaner