Valves tight ,, why?

My DP 1776 developed a miss and I found the compression low on 1 & 2 .
Then I checked the valves and found them tight. I'm going to check them
again soon, Could they be stretching ? What else could it be?
--
If guns are out-lawed. Only the Out-laws & politicians will have guns.

On Sun, 31 Aug 2008 04:32:05 +0200, former POW
> wrote:

> My DP 1776 developed a miss and I found the compression low on 1 & 2 .
> Then I checked the valves and found them tight. I'm going to check them
> again soon, Could they be stretching ? What else could it be?

Sinking valveseats?

J.



--
Using Opera's revolutionary e-mail client: http://www.opera.com/mail/

Did you check them while the engine was cold?
How often do you check them?

"P.J.Berg" > wrote in message
news
> On Sun, 31 Aug 2008 04:32:05 +0200, former POW
> > wrote:
>
>> My DP 1776 developed a miss and I found the compression low on 1 & 2 .
>> Then I checked the valves and found them tight. I'm going to check them
>> again soon, Could they be stretching ? What else could it be?
>
> Sinking valveseats?

In article >,
"dave AKA vwdoc1" > wrote:

> Did you check them while the engine was cold?
> How often do you check them?
>
> "P.J.Berg" > wrote in message
> news
> > On Sun, 31 Aug 2008 04:32:05 +0200, former POW
> > > wrote:
> >
> >> My DP 1776 developed a miss and I found the compression low on 1 & 2 .
> >> Then I checked the valves and found them tight. I'm going to check them
> >> again soon, Could they be stretching ? What else could it be?
> >
> > Sinking valveseats?

as I understand the Muir's book. if you adjust them above 122 degrees F.
you set them too tight. right?
as it was I reset them and the compression reading came back to match
cylinders 3 & 4. 125 or so.
Wish me Luck
OK?
--
If guns are out-lawed. Only the Out-laws & politicians will have guns.

LUCK! ;-)

You should be fine.
BTW I usually check the torque of the lower cylinder head nuts before I
adjust valves. I think the Muir book recommends that.
--
later,
(One out of many daves)

"former POW" > wrote in message
...
> In article >,
> "dave AKA vwdoc1" > wrote:
>
>> Did you check them while the engine was cold?
>> How often do you check them?
>>
>> "P.J.Berg" > wrote in message
>> news
>> > On Sun, 31 Aug 2008 04:32:05 +0200, former POW
>> > > wrote:
>> >
>> >> My DP 1776 developed a miss and I found the compression low on 1 & 2 .
>> >> Then I checked the valves and found them tight. I'm going to check
>> >> them
>> >> again soon, Could they be stretching ? What else could it be?
>> >
>> > Sinking valveseats?
>
> as I understand the Muir's book. if you adjust them above 122 degrees F.
> you set them too tight. right?
> as it was I reset them and the compression reading came back to match
> cylinders 3 & 4. 125 or so.
> Wish me Luck
> OK?
> --
> If guns are out-lawed. Only the Out-laws & politicians will have guns.

On Aug 31, 9:07*pm, "dave AKA vwdoc1" >
wrote:
> LUCK! *;-)
>
> You should be fine.
> BTW I usually check the torque of the lower cylinder head nuts before I
> adjust valves. *I think the Muir book recommends that.

I concur -- loose heads would cause strange problem like this. Now,
if the heads are loose you may have other problems. If the engine was
running hot for a long drive, they would do it.

-Steve Ballantyne
68' Bug

On Sat, 30 Aug 2008 19:32:05 -0700 former POW
> wrote:

>My DP 1776 developed a miss and I found the compression low on 1 & 2 .
>Then I checked the valves and found them tight. I'm going to check them
>again soon, Could they be stretching ? What else could it be?

Valves and valve seats wear. As they wear, the valve clearance goes
down, so it's normal for valves to tighten up at some rate. If this is
happening quickly, then something unusual may be going on, but
"quickly" is subjective.

I find that I have to adjust 2-3 valves just a bit every 3000 miles,
but they should never be at zero clearance in that time unless you're
running the engine really hard or really hot.

BTW, if you have head studs coming loose, that will show up as loose
valve clearance, not tight. And, yes, you should always adjust the
valves with the engine at room temp.

-
-----------------------------------------------
Jim Adney
Madison, WI 53711 USA
-----------------------------------------------

In article >,
Jim Adney > wrote:

> On Sat, 30 Aug 2008 19:32:05 -0700 former POW
> > wrote:
>
> >My DP 1776 developed a miss and I found the compression low on 1 & 2 .
> >Then I checked the valves and found them tight. I'm going to check them
> >again soon, Could they be stretching ? What else could it be?
>
> Valves and valve seats wear. As they wear, the valve clearance goes
> down, so it's normal for valves to tighten up at some rate. If this is
> happening quickly, then something unusual may be going on, but
> "quickly" is subjective.
>
> I find that I have to adjust 2-3 valves just a bit every 3000 miles,
> but they should never be at zero clearance in that time unless you're
> running the engine really hard or really hot.
>
> BTW, if you have head studs coming loose, that will show up as loose
> valve clearance, not tight. And, yes, you should always adjust the
> valves with the engine at room temp.
>
> -
> -----------------------------------------------
> Jim Adney
> Madison, WI 53711 USA
> -----------------------------------------------

I checked them today after sitting in 48 degrees over night.
Drove 30 miles since the "correction" now they are fine.

thanks, group for the suggestions.
--
If guns are out-lawed. Only the Out-laws & politicians will have guns.

On Aug 30, 7:32*pm, former POW > wrote:
> I checked the valves and found them tight. *I'm going to check them
> again soon, Could they be stretching ?

--------------------------------------------------------------------------

It's time for a valve job.

In the VW valve train, wear accumulates at the interface between the
cam and the cam-follower, between the cam-follower and the push-rod,
between the push-rod and the rocker-arm, between the rocker arm and
the rocker-arm shaft, and finally between the adjusting screw and tip
of the valve stem. This accumulation of wear is dealt with by the
adjusting screw. After about five adjustments the face of the
adjusting screw will become faceted and the adjusting screw must be
replaced. The accumulation of wear on the rocker-arm shaft appears as
galling on the side of the shaft nearest the head. Standard procedure
is to dismantle the rockker-arm shaft and reverse it, presenting an
un-worn surface to the rocker arms.

You will note that in each of the above cases the accumulation of wear
results in the adjustment becoming WIDER.

The ONLY time the adjustment can become SMALLER is when the valve
stretches OR the valve seat is driven deeper into the head.

Both of these cases begin as heat-related phenomena, aided by hot-rod
conventional wisdom that sez bigger valves and stronger springs --
are inherently better. In fact, the larger the diameter of the valve,
the hotter it is going to run since its amount of heat-transfer
surface is now proportionally small than for a smaller valve.

In the same manner, when the valve spring(s) are stronger than stock
their excessive tension promotes 'necking' or stretching of the valve.

It is also worth mentioning that the use of larger valves and stronger
springs is a technique used primarily in LIQUID-COOLED engines, where
cylinder head temperatures are typically less than 200 degrees
Fahrenheit. Apply that same technique to an air-cooled engine having
CHT's as high as 450 degrees and you have virtually guaranteed
stretched valves and failed valve seats.

-R.S.Hoover

On Sep 6, 4:03 pm, Bob Hoover > wrote:
> On Aug 30, 7:32 pm, former POW > wrote:
>
> > I checked the valves and found them tight. I'm going to check them
> > again soon, Could they be stretching ?
>
> --------------------------------------------------------------------------
>
> It's time for a valve job.
>
> In the VW valve train, wear accumulates at the interface between the
> cam and the cam-follower, between the cam-follower and the push-rod,
> between the push-rod and the rocker-arm, between the rocker arm and
> the rocker-arm shaft, and finally between the adjusting screw and tip
> of the valve stem. This accumulation of wear is dealt with by the
> adjusting screw. After about five adjustments the face of the
> adjusting screw will become faceted and the adjusting screw must be
> replaced. The accumulation of wear on the rocker-arm shaft appears as
> galling on the side of the shaft nearest the head. Standard procedure
> is to dismantle the rockker-arm shaft and reverse it, presenting an
> un-worn surface to the rocker arms.
>
> You will note that in each of the above cases the accumulation of wear
> results in the adjustment becoming WIDER.
>
> The ONLY time the adjustment can become SMALLER is when the valve
> stretches OR the valve seat is driven deeper into the head.
>
> Both of these cases begin as heat-related phenomena, aided by hot-rod
> conventional wisdom that sez bigger valves and stronger springs --
> are inherently better. In fact, the larger the diameter of the valve,
> the hotter it is going to run since its amount of heat-transfer
> surface is now proportionally small than for a smaller valve.
>
> In the same manner, when the valve spring(s) are stronger than stock
> their excessive tension promotes 'necking' or stretching of the valve.
>
> It is also worth mentioning that the use of larger valves and stronger
> springs is a technique used primarily in LIQUID-COOLED engines, where
> cylinder head temperatures are typically less than 200 degrees
> Fahrenheit. Apply that same technique to an air-cooled engine having
> CHT's as high as 450 degrees and you have virtually guaranteed
> stretched valves and failed valve seats.
>
> -R.S.Hoover

Regarding 'hot rod' engines with larger valves, Bob, would you say
this increased heat is a side effect that's bound to happen, as the
larger springs generally complement hotter cams in order to prevent
valve float?