Also, the '68-70 distributors originally came equipped with a smog 17.5 degree
advance rotor cam (producing 35 degrees of centrifugal advance at the
crankshaft). This makes the engine perform poorly (along with potential
overheating problems) at lower engine speeds because the timing has to be set
back to 0 degrees BTDC at idle. You want the 7.5 advance rotor cam, which came
on the pre-'68 roadsters. The 7.5 cam produces 15 degrees of advance and
allows your idle timing to be set at 16 degrees BTDC (20 for Solexes). You can
easily determine whether your distributor has been de-smogged to the 7.5 cam by
either watching with a timing light to see how much the timing advances
(assuming your advance mechanism is working properly) as you rev the engine
from idle to 4000 rpm, or remove the breaker plate and see what number is
stamped on the rotor plate underneath. To remove the breaker plate, remove the
vacuum controller and the 2 screws securing the breaker plate to the
distributor housing. There's no need to remove the points from the breaker
plate, so you won't have to worry with resetting the points gap or dwell
afterward. If the rotor cam says 7.5, that's good. If it's 17.5, that's bad.
While you have the breaker plate out, check the condition of the centrifugal
advance mechanism for frozen or damaged weights and springs.
Gary Boone
'70 2000
http://www.picturetrail.com/gboone
WyCROC http://www.wycroc.org/
Adam Bradley wrote:
> The '70 has a closed fuel system. There is a small tank on the top of the
> trunk. If you remove all the lines and cap it all off you risk
> overpressurizing your fuel system, which could result in very nasty
> things. Also, it has nothing to do with smog emissions but rather with gas
> vapors coming out your fuel tank. Leave it alone unless you're willing to
> convert ALL of that to pre-70 stuff.
>
> I'm not familiar with a vent on the dip stick. I don't have this on my '70
> 1600. However again if you're looking to reduce weight and improve
> performance, something like that isn't going to do it. If the smog pump,
> hoses that attach directly to it, and the air injection rail are gone, you
> are pretty much de-smogged. There isn't much more to remove.
>
> One possible performance robbing "feature" on the '70 is the float bowl
> overflow to the air filter. You may want to get longer fuel hose and route
> it to the ground rather than the air filter. There has been talk of the
> intake creating a vacuum in the float chamber, which would impact fuel
> delivery.
>
> At 07:44 AM 8/16/2002 -0600, Brad Holmes wrote:
> >Since were on SUs, I recently bought a 70 - 2000 California car that
> >has been de-smogged. The PO or the pre-PO has removed much of the
> >devices and plugged ports and did a recurve. There are still a bunch
> >of lines running around, to and from the tank. A couple questions.
> >1. Can ALL the rest of the smog equipment also be removed and lines
> >and ports plugged, on the tank and in the engine room?
> >2. Can the vent on the dip stick be capped off?
> >3. What is/was the purpose of the "valve, fuel return assy, rear"
> >next to the rear SU? (F8B-1, item 119, top left of the pic in the
> >parts manual) http://www.gordon-glasgow.org/Images/8B.gif
> >Can the valve be removed and a regular fitting be installed?
> >
> >Thanks
> >Brad Holmes
> >68 - 2k, Solex
> >70 - 2k, SU
> >SEROC
> >OROC
> >
> >/// datsun-roadsters@autox.team.net mailing list
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>
> Adam Bradley
> '70 Datsun 1600 Roadster SPL311-28181
> '67 Datsun RL411 SSS sedan RL411-11321
> '66 Datsun PL411 sedan PL411-022447
> http://www.picturetrail.com/abend
>
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