Yeah, those numbers are from the 1600/2000 Service Manual.
The whole issue of cam timing and idle is way more complex than we would
want to get into here, but in brief, it's a matter of valve overlap between
intake and exhaust, which is affected not only by overall duration and cam
profile by also by the lobe separation angle.
Absolutely the best, most thorough and most readable explanation I've ever
found of all this is the chapter on camshafts in the old "How To Modify
Datsun Engines & Chassis" book by Fisher and Waar. The camshaft chapter was
written by Racer Brown and is 44 pages long. Unfortunately this book has
been out of print for years. Last time I looked on the Web, I found one copy
at a bookstore in SF and they wanted $169 for it!
Gordon Glasgow
-----Original Message-----
From: datsun-roadsters-bounces@autox.team.net
[mailto:datsun-roadsters-bounces@autox.team.net] On Behalf Of dave
Sent: Friday, May 29, 2009 5:49 PM
To: 'Toby B'; datsun-roadsters@autox.team.net
Subject: Re: [Roadsters] Datsun-roadsters Digest, Vol 3, Issue 225
I think tat would be advertised. Old school numbers :)
Generally IIRC, about 280-285 is where the idle gets ugly and low end starts
to drop off.
Dave Brisco
-----Original Message-----
From: Toby B [mailto:RacerY@comcast.net]
"For a 4-cylinder engine, once you start getting close to 300 degrees
duration, it becomes marginally streetable. The stock SU cam is 256 degrees;
the Solex cam is 280 degrees.
Gordon Glasgow"
Hey Gordon, is that at .050" lift? 1mm?
(BMW does it at .5mm, I think, and it gives numbers that make
the hotrodders (.050") cringe...)
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