Bruce:
As Yogi Berra observed "Its Deja Vu all over again". Remarkably
similar to my story on my Z28. Here is a cam that is very close to what
I want, but it is JUST A LITTLE more aggressive. What can it hurt? The
answer: quite a bit.
This is what many people, including myself, have found. When you
are pushing the envelope, the drivability falls off pretty quickly, and
while it is fun for a while long term satisfaction goes out the window.
In this case, you chose the right duration, but the lobe center
spacing got you. I had a later TR6 cam, and the regrinder gave me 270
duration, but with a 109 LS. The cam is very civil with a decent (but
not glass smooth) idle. Pulls nicely from 1,200 RPM up, and idles at 900
RPM all day long. Runs regular gas without a complaint. Lobe center
spacing makes all the difference.
I have no doubt that your motor makes more power and it probably
sounds really sexy too. That is the upside of tighter lobe centers. My
point here is that depending on what parameter you are talking about, a
couple degrees difference really matters, and for the daily driver kind
of car too much leads to regrets. Mike Crane in our local Triumph club
had a pretty similar experience. In his case he bought a new (I think)
PI cam. I asked him how he liked it, and he said "It runs great, but
idles like a rock crusher".
My latest motor project is a 1380cc mini. 260i/270e, 106LS.
Should be very civil and I am aiming for 105HP, or 76 HP/liter. That
would be 190 or so on our TR6s. Impressive if everything works, which
according to David Vizard it should. With that short duration idle and
torque should be terrific. I will let everyone know how it turns out.
Vance
-----Original Message-----
From: owner-6pack@Autox.Team.Net [mailto:owner-6pack@Autox.Team.Net] On
Behalf Of Bruce Simms
Sent: November 15, 2007 8:23 AM
To: 6pack@autox.team.net
Subject: [6pack] Cam Opinions
<snip>
I wanted the re-grinders 270/.398 profile TR6 cam, but he said he
couldn't get there with my earlier TR6 cam. I ended up with his TR6 PI
profile, 270/.375 105 lobe sep.
Lots of power and excitment available from about 2800 rpm when cam comes
on. While this is okay, for my situation I wish the power started at
lower rpms. When I drive the 6 as daily transportation in my city I
don't get above 4000 rpm all that much, particularly as I have OD.
Idles nicely with a little lope at about 1100 rpm.
<snip>
My mileage went down and now I use high octane. Speed (fun) costs.
Bruce Simms
73 TR6
|