[DML] Re: Brass Manifold Screws

["content22207" <brobertson@xxxxxxxxxxxx>]

Actually the brass screws are the idle speed system used before CIS.
They are used by *ALL* K Jetronic equipped PRV's from the mid 1970's
until the early 1980's. In the DeLo ap these screws weren't put on,
but rather were left behind. 

Volvo did decide that they shouldn't be messed with after CIS, so it
replaced the balancing screws with a "shear head" style, and
instructed mechanics to tighten them until the heads broke off. I've
re-uploaded to #5939's photo album a page from Volvo factory
literature documenting such.

Note that the threaded portion of all three screws is identical. If an
owner wants to reactivate the manual idle speed circuit, shear head
balancing screws can be replaced with air inlet screws. Don't forget
to replace the O rings at the same time.

Note also that Renault never adopted CIS -- it never used shear head
style balancing screws. 

Interestingly, last weekend I bought an upper air assembly from a 1989
B28F that, although CIS equipped, did NOT have shear head balancing
screws. Either Volvo itself or a previous owner had adopted John
Hervey's philosophy by the end of the decade.

Bill Robertson
#5939

>--- In dmcnews@xxxxxxxxxxxxxxx, "John Hervey" <john@xxxx> wrote:
> John,
> Adjusting and compensating for wear is why they put screws one the
area's
> that need to be adjusted. If you want to pull the fuel system out
and take
> the intake off to get to the vacuum hoses while following someone's else
> advice then please do so. But if you feel that is a little to much. Then
> screws are made to be adjusted. You can also try it and if it
doesn't work
> then put it back with out having to a complete tune up. Trying to find
> vacuum leaks is easy to say but not always easy to do. Even a tune
up on our
> cars is somewhat difficult. There is a screw for the 02 sensor
adjustment
> ( fuel enrichment or lean ), idle speed, idle speed motor turn on.
If you
> have or even know someone that has an Ultrasonic cleaner that can
clean and
> test injectors then that is a good option. If you don't know someone
then
> you can pull them off and send them to me and I will clean them. 2
day's in
> house and 2 day's ea coming and going, so you will be down for about
8 to 10
> day's if that is an option.
> John Hervey
> www.specialTauto.com
> 
> 
> 
> 
> -----Original Message-----
> From: David Teitelbaum [mailto:jtrealty@xxxx]
> Sent: Thursday, March 18, 2004 9:17 AM
> To: dmcnews@xxxxxxxxxxxxxxx
> Subject: [DML] Re: VIN 5326 started
> 
> 
> You don't get the PRV running by "adjusting" things. If it is not
> running right then it usually means you have to replace or clean
> parts. "Ajusting" the O2 sensor (I assume you messed with the mixture
> screw) only caused you to lose that adjustment. If it won't start than
> you don't begin by messing with adjustments. Start with finding and
> fixing vacuum leaks. Next have the fuel injectors cleaned and do a
> tune-up replacing the spark plugs, ignition wires, cap, rotor, and air
> filter. NOW you adjust the mixture screw on an engine analyzer. In
> fact that is the only thing to adjust unless you also messed with the
> 3 brass screws and the tiny screws on the micro switchs by the
> throttle spool. Timing generally is "right on" or close enough not to
> need adjustment. You do have to make sure the mechanical advance and
> the vacuum advance are working though. If it is smoking a lot pressure
> test the cooling system to find any leaks and do a compression test on
> the cylinders to see if it has been overheated.
> 
> 
> --- In dmcnews@xxxxxxxxxxxxxxx, "painintheass7565" <advantics@xxxx>
wrote:
> > Howdy all.Yup, if you can believe it, VIN 5326 will start but run
> > ruff after adjusting the O2. You have to give it gas to start it and
> > keep it running, and she smokes a lot.I remember someone saying that
> > I would have to adjust the frequency valve once I got it started, but
> > I don't know how to do that. I'm open to all suggestions. I just want
> > to thank everyone again for all your help.
> >
> > John 5326 & 1383
> 
> 
> 
> 
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