You will also need the displacement angle/lobe center angle to compare
the different cams. Less lobe center makes more overlap and less power
at bottom end but more on top rpm. I have no experience with R & U
engines but many L series cams were ground on 109 degree lobe centers.
This made it possible to run a much duration and still have reasonable
low rpm driveability. With the same profile and duration but with 105
degree lobe centers the engine made a lot more power on top end but
a lot less on the lower rpm. Twin cam engines with variable valve timing
can have it both ways. It's used for both for emissions and max. power
depending on which cam is adjusted and at what rpm.
Thomas
STAN CHERNOFF wrote:
> Cams are very complex items and the lift/duration numbers don't necessarily
> define what the performance will be.
>
> Duration is usually called out at some small valve lift, maybe 0.050", but
> can be 0.030" as is a cam that I have. The rate of opening can be a very
> significant factor in performance. If the opening and closing ramps are
> fast it gives the cylinder more time to breathe than a cam with gentle
> ramps while both have the same duration. The cam lift is only the
> effective difference between the base circle radius and the radius of the
> highest point on the lobe.
>
> As far as I know there are no "NEW" R-16 cams made for improved
> performance. All of the R-16 cams discussed in the recent postings are
> regrinds including the Nissan 9/6-B1020 and 9/6-B1021 racing cams. Col.
> Joe used a couple of cams that were part of a small batch of "Billet" cams.
> The billet blanks were made in Southern california and sent to Virginia to
> be ground according to info supplied by Col. Joe. The billets were made
> from steel instead of cast iron and had a distributor drive gear with a
> Chevy design because they didn't have the capability to cut the Datsun one.
> It was necessary to run a brass driven gear because of metallurgy.
>
> I am not an expert on cam design but wanted to caution that comparing cam
> spec's doesn't tell the whole story. You must trust your cam grinder and
> his experience with similar applications.
>
> Stan
> ==============
>
> At 09:48 PM 2/4/01 -0800, Victor Laury wrote:
> >On Rob's page, Col. Joe describes his special grind as Lift .350" Dur 250.
> >Compared to the specs below, that would seem way mild. What's up with that?
> >
> >----- Original Message -----
> >From: Gordon Glasgow <glasgow@serv.net>
> >To: <datsun-roadsters@autox.team.net>
> >Sent: Sunday, February 04, 2001 8:50 PM
> >Subject: RE: R 16 Cams
> >
> >
> >Racer Brown 324R Lift .475"; dur. 262 deg.
> >Racer Brown 325R Lift .475"; dur. 275 deg.
> >
> >Gordon Glasgow
> >Renton, WA
> >
> >-----Original Message-----
> >From: owner-datsun-roadsters@autox.team.net
> >[mailto:owner-datsun-roadsters@autox.team.net]On Behalf Of Henry Bahn
> >Sent: Sunday, February 04, 2001 7:39 PM
> >To: Teesun68; STAN CHERNOFF; datsun-roadsters@autox.team.net
> >Subject: R 16 Cams
> >
> >
> >Some 1600 cams, in increasing order of performance. Anyone know of others?
> >
> >Nissan P/N 13001-18810; specs unknown
> >NISMO P/N unknown; Lift .480"; dur. 300 deg.
> >Chambers P/N 250-353: Lift .353"; dur. 250 deg.
> >Isky P/N W84N; 6626cc . . . Lift .420"; dur. 266 deg.
> >PAECO P/N DS-6000 Lift .367"; dur. 266 deg.
> >PAECO P/N DS-6800 Lift .421"; dur. 270 deg.
> >PAECO P/N DS-7200 Lift .430"; dur. 288 deg.
> >PAECO P/N DS-7800 Lift .434"; dur. 295 deg.
> >Tilton P/N unknown Lift .480"; dur. 310 deg.
> >
> >JH Bahn
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