[T3] Tight exhaust valves

[Jacob Adam Schroeder]

Great, thanks Dave.  Your explanation is very helpful.  I think I'll run
out and pick up new vacuum hoses and continue to use my golf tee plug
system.  I will see if that makes any difference in the idle variation.

I agree with Jim that some variation is common, but the perfectionist in me
knows that it holds a steady idle when all the hoses are connected and so
I'm curious why it cannot do so with the hoses disconnected and plugged.




On Fri, Dec 27, 2013 at 10:47 AM, Dave Pallo <rdavid at rochester.rr.com>wrote:

> [[[On the timing issue, I have a '72 and I follow the procedure in Bentley
> (roughly: set idle, confirm throttle is closed by pulling 1 dist. hose and
> observing timing mark, pull & plug both hoses, reset idle, time, re-connect
> hoses, reset idle).  When I have both distributor hoses off to set the
> timing, my engine always surges a bit, so the timing mark moves. I just get
> it so the center of the swing is the proper timing and assume that is OK.
>
>
>
> If anybody else has a '72 out there, do you experience this similar surging
> at idle when both your distributor hoses are disconnected? It is maybe a
> swing from 820-870 (so still within the 850 +/- 50), but enough to make the
> timing mark move.]]]
>
>
>
> Following the Bentley timing procedure is the right thing to do. It tells
> you what to do (but not why), so if you follow the Bentley directions for
> 72
> - you'll time it correctly.
>
>
>
> .         For a 72, it is very important that the throttle plate fully
> closes. This enables the vacuum retard port to have vacuum at idle (also
> very important). A correctly adjusted throttle valve switch will not stop
> the throttle plate from closing fully.
>
> .         The idle speed screw does not provide a mechanical stop for the
> plate (as in carbed engines), but instead allows a very small amount of air
> into the IAD to control idle speed. This screw will not hold the throttle
> plate open at all.
>
> .         For a '72, the vacuum retard is what pulls the points plate back
> AT IDLE and makes it possible to achieve the 850 rpm at idle. That is why
> we
> have vacuum retard. If you are correctly timed at 5 degrees, and your
> vacuum
> retard is not working - you more than likely won't be able to adjust the
> idle speed screw enough to get the idle down to 850 rpm.
>
>
>
> This are some reasons why you have to follow the Bentley. The '72 motor
> needs to be timed at 850 without vacuum influence, but as soon as you
> connect the vacuum lines; the points plate moves - and so will the timing
> marks, and therefore the idle speed. That's why you are going back and
> forth
> with setting idle speeds when setting the timing.
>
>
>
> The surging you are seeing is not good for timing a motor - any motor,
> regardless of year, FI or carbed. This is not a '72 thing. You are probably
> correct in looking for any vacuum leaks, as that will cause surging. It's
> probably not your golf tees, as we all use 'em ;-)
>
>
>
> And Thanx for the props, Bob! Experience is the best teacher, isn't it?
>
>
>
>
>
> Dave Pallo
>
> '72 Square ~ Elwood
>
> Fairport, NY
>
>
>
>
>
>
>
>
>
>
>
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL: <
> http://lists.vwtype3.org/pipermail/type3-vwtype3.org/attachments/20131227/ba548d49/attachment.htm
> >
> _______________________________________________
> VWType3.Org mailing list - type3 at vwtype3.org
> http://lists.vwtype3.org/listinfo.cgi/type3-vwtype3.org
> Contact gregm at vwtype3.org if you need help with the list.
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.vwtype3.org/pipermail/type3-vwtype3.org/attachments/20131228/a0fb4d4b/attachment.htm>