Re: Idle With Brass Manifold Screws

["content22207" <brobertson@xxxx>]

Lower screw in your pic merely cracks throttle plates (like a
carburetor). Works, but odd fire PRV has tendency to rock & roll like
that. Brass manifold screws accomplish same function with smoother idle.

While manifold screws are generally considered taboo in DeLo world,
are in fact the ONLY way to idle Volvo B27 and Renault R30 (my
replacement block). Those engines do have same hose barbs as DeLo idle
speed motor (barb under fuel distributor is premanently attached, not
O ringed) but use for auxiliary air valves only (fast idle on cold
engine). Idle itself properly set with manifold screws and exhaust gas
analyzer. Is also a poor man's method using tachometer.

B27 and R30 have no place on fuel mixture unit to attach idle
microswitch BTW.

Volvo went to CIS on B28. Also went to two piece fuel mixture unit to
"dampen intake system vibrations" (factory literature) and added
deceleration valves in throttle plates themselves.

Bill Robertson
#5939

>--- In dmcnews@xxxxxxxxxxxxxxx, "John Hervey" <john@xxxx> wrote:
> Dave, There is a lot of reference information on the web site.Here
is the
> link to the picture you need.The idle speed is adjustable.
> John Hervey
> http://www.specialtauto.com/delorean-images/idle-speed-adj.jpg
> 
> -----Original Message-----
> From: Soma576@xxxx [mailto:Soma576@xxxx]
> Sent: Sunday, November 16, 2003 9:09 AM
> To: dmcnews@xxxxxxxxxxxxxxx
> Subject: Re: [DML] Re: idle yet again
> 
> 
> In a message dated 11/15/03 3:00:33 PM Central Standard Time,
> doctorDHD@xxxx writes:
> 
> > My car, 6530, idles irregularly and at 900 - 1200 with both the idle
> > speed screw and the ECU screw out all the way. Am I screwed up?
> >
> > Dave and 6530
> >
> 
> what is the idle speed screw? What is the ECU screw? are you
referring to
> the primary idle speed screw (not used since there is electronic idle
> control on
> this car). the first screw (closest to the mixture unit) should be
lightly
> closed. the other two are balancing screws for the left and right banks
> (also
> not used). you should close all three screws and then continue
tuning. it
> might just be the problem, since you are not allowing the idle speed
motor
> to
> fully regulate air flow at idle when the screws are open.
> 
> idle is electronically controlled and is not setable, per se. you can
> increase idle speed by changing the position of the throttle stop
screw, but
> in a
> stock engine, it should be screwed down about 1/4 turn from the
point where
> the
> throttle closes by itself w/o a stop screw. the stop screw keeps it
from
> binding up or getting damaged. you should not be playing with this
screw
> other
> than to set it at precisely that point. when it is screwed in too far
> (raise
> the idle), you are allowing air to get past the butterfly plates, again
> bypassing the idle speed motor and not allowing it to do its job
properly.
> 
> some discussion in recent weeks have pointed to a good use of the three
> brass
> idle screws to help smooth out the idle, but do not try this until
> EVERYTHING
> is 100% perfect. you don't want to introduce more variables while
fixing a
> problem!
> 
> Andy
> 
> 
> [Non-text portions of this message have been removed]
> 
> 
> 
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