[6pack] SU Needle Selection

[Bruce Simms]

Thanks Vance.  That was educational for me.   
Bruce Simms
________________________________
From: Vance Navarrette
<v.navarrette at comcast.net>
To: Bruce Simms <brucesimms2003 at yahoo.ca>;
6pack at autox.team.net
Sent: Mon, May 9, 2011 4:21:43 PM
Subject: RE: [6pack] SU
Needle Selection

    Bruce:

    That is the cost of the TR5 cam, with its
tight lobe centers.

    Both valves are open for a significant amount of
time, which allows
the intake charge to push the exhaust gases out of the
cylinder. This makes
for an uncontaminated intake charge and good power, but a
portion of the
intake charge gets blown out of the exhaust before the exhaust
valve closes.

    Hits economy pretty hard as you have seen, and emissions go
through
the roof. The unburned intake charge shows up in the exhaust gasses as
hydrocarbons (HC).

    Modern cams use wider lobe centers and about 10
degrees more timing
on the exhaust than the intake, which avoids these
problems. The TR5 cam may
be very old school, but no one was ever disappointed
with the power.

    Vance

-----Original Message-----
From:
6pack-bounces at autox.team.net [mailto:6pack-bounces at autox.team.net] On
Behalf
Of Bruce Simms
Sent: Monday, May 09, 2011 1:39 PM
To: 6pack at autox.team.net
Subject: [6pack] SU Needle Selection

I have TR5 280 cam, 9.5 head etc.
<snip>

Good power, but its thirsty.

Bruce Simms
73 TR6