Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.1 6/24/83; site alice.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!allegra!alice!wookie
From: wookie@alice.UUCP
Newsgroups: net.auto
Subject: Re: help with camshafts and vacuum assist
Message-ID: <2937@alice.UUCP>
Date: Wed, 25-Jul-84 12:25:09 EDT
Article-I.D.: alice.2937
Posted: Wed Jul 25 12:25:09 1984
Date-Received: Fri, 27-Jul-84 04:44:25 EDT
References: <2739@decwrl.UUCP>
Organization: AT&T Bell Laboratories, Murray Hill
Lines: 18

The camshaft you have installed has a higher "valve overlap"
meaning the exhaust valve and intake valve are open at the
same time for a longer duration than the stock shaft.  This
is what produces the poorer idle in a hotter cam.  The reason
for this higher duration is to allow the exhaust to flow out
and the intake mixture to flow in better at higher RPM.  The
result is poor idle and poor vacuum at low speeds.  The carb
installation should not affect the vacuum and yes a larger
reservoir will help some but you're probably only getting a
good vacuum when going down a long hill and so won't be able
to store much away the rest of the time.  This is a common
problem and most people just do away with the brake assist.

There is no way I can have a brake assist on my Sunbeam race
car!  The engine rarely produces and vacuum!!

				Keith Bauer
				White Tiger Racing