I can't speak to needle profile on the 1600 but that would be just about
last on my list. I was running 204Z needles in my 2L with no problems.
Yesterday there was a bit about the float bowl overflow lines running to the
air cleaner drawing a vacuum on the float chamber and causing a lean
condition at higher RPM. How are you're fuel lines routed. After that, I'd
start with the dist. advance mechanism.
Brian
-----Original Message-----
From: owner-datsun-roadsters@autox.team.net
[mailto:owner-datsun-roadsters@autox.team.net]On Behalf Of Pam & Paul Bauman
Sent: Tuesday, May 01, 2001 1:58 AM
To: Autox
Subject: 3000 rpm rattle
While getting my car ready for Solvang, I took it over to Bill Meyers to
have it tuned for the trip. Bill does engine work for CDM and I regard his
knowledge of roadster engines highly. He noted that my car seemed to be
suffering from a mid-range loss of power (bogging down, backfiring) that
many SU-equipped cars he has worked on here in California have been
experiencing of late. The engine could be made to idle correctly, but lost
power at higher RPMs. It could be made to run at higher RPMs (3000-5000
RPM), but would idle poorly. He is determined to correct this problem, and
seems to think that a change in carb needle profile is needed, perhaps
because of the changes in modern gas formulation.
Bill would like to make up some experimental needles and test their
operation in a dyno booth. It would take a 'guinea pig' roadster with SUs
and either some spare SU carbs or a couple of additional cars to get some
spare suction pistons to install the test needles. I thought perhaps the
SoCalROC crowd would be willing to chip in some money to afford some time in
the dyno. Bill said that the facilities often rent time out to clubs at a
reduced rate and sometimes allow members to view the testing in progress!
It sounds like a worthy cause to me--providing our poor SU babies with the
means to run well on 21st century gas. Drop me a line off list if you would
be interested in participating in a grand experiment, either as a patron--or
perhaps donating your car as a 'lab rat'.
TIA
Paul Bauman
Westminster, CA
67 1600
http://www.PictureTrail.com/bauman311
|