[T3] Tight exhaust valves

Dave Hall dave at hallvw.clara.co.uk
Sun Dec 29 17:21:09 PST 2013


If there's any centrifugal advance active at around 850 rpm, if the engine
changes rpm the timing changes slightly too, which can produce mild
'hunting'.  I have noticed this effect at some point on one of the Type 3s,
but I don't recall under what circumstances.  I have dual vac units on the
'71 twin carb and the '72 FI, though the timing is done differently on each
(TDC hoses on for twin carb, 5 BTDC hoses off for FI.  

The two pipes on the vac unit have different bores - one is quite small - so
maybe that produces a dsmping effect(another WAG!).

Dave
UK VW Type 3&4 Club
===================
-----Original Message-----
From: type3-vwtype3.org-bounces at lists.vwtype3.org
[mailto:type3-vwtype3.org-bounces at lists.vwtype3.org] On Behalf Of Jim Adney
Sent: 29 December 2013 15:30
To: type3 at vwtype3.org
Subject: Re: [T3] Tight exhaust valves

On 28 Dec 2013 at 10:00, Jacob Adam Schroeder wrote:

> 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.

I guess I didn't read your question carefully enough; I didn't realize that
the unsteady idle complaint was just with the dist vac hoses disconnected.

In that case, it's possible that the '72-only vac retard is part of the idle
stabilization for this engine, and with it disabled you get a less stable
idle.

That's just a WAG (Wild Ass Guess.)

--
*******************************
Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
*******************************

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