Prior to the PCV valve (which was prior to yours) there was just a hose from
the rocker cover to the air filter box and an open pipe on the front cover
or front tappet chest cover. Fumes could vent either way according to
whether the greatest suction was in the air filter i.e. large throttle
opening or the draft tube i.e. high road speed.
A 74 (originally) had the best crankcase ventilation system i.e. no PCV
valve and restricted carb suction. If you are having problems sealing the
front cover then if you can't find and fix the reasons a replacement cover
of the same type would be best. The problem with the draft tube system is
that ventilation was iffy and could draw in unfiltered air. A scrapyard or
dismantler is probably the only source of replacement of either type.
You are as likely to have leaks with the draft tube type of front tappet
chest cover as the correct type. You might as well opt for the correct
cover, since the sealing is the same with all three types of ventilation.
PaulH.
----- Original Message -----
From: "Christian, Wellner L. CIV COMNAVAIRSYSCOMPATUXENTRIVERMD AIR 4.1.1.4"
<wellner.christian@navy.mil>
To: "MG Digest (E-mail)" <mgs@autox.team.net>
Sent: Friday, March 05, 2004 2:59 PM
Subject: Exhaust System and PCV Questions
> 2) Does anyone know of where I can get (by mail) a replacement front
tappet
> cover for my MGB??? I'd like to get either an MGA or a 18G version. I
plan
> to run a draft tube. The reason I'm doing this is so I can install the
front
> cover (correctly :) and not worry about leaks.
> 3) Also, does anyone know where, prior to PCV, the engine vapors were
vented
> from??? Did they just have the side vent (tube) and no vent on the valve
> cover??
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