Date: Fri, 7 Feb 2014 05:33:33 -0600
Reply-To: Max Wellhouse <dimwittedmoose@CFU.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Max Wellhouse <dimwittedmoose@CFU.NET>
Subject: Re: air cooled 2.0 1981 Cylinder head temp?
In-Reply-To: <BAY179-DS3C8A904839D123934D58AA0970@phx.gbl>
Content-Type: text/plain; charset=UTF-8; format=flowed
On 2/6/2014 10:21 PM, Dennis Haynes wrote:
> On these engine you will find a head temp gauge to be a fantastic fuel
> saving device especially for the Vanagon. You will discover the max speed
> for temp control real fast.
> Under the spark plug you are really getting the spark plug temperature.
> Where the location of the thermocouple ends up can have an effect on the
> readings. Get that junction on top so it gets some airflow and you can get a
> lower reading.
>
> 375 to 425 seems to be common range for 65 and under driving. Having a
> working EGR system can lower the temp significantly. For extended high speed
> operation premium fuel will help especially if the EGR system is missing.
>
> Dennis
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
> Glen Moon
> Sent: Thursday, February 6, 2014 4:06 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: air cooled 2.0 1981 Cylinder head temp?
>
> Rebuilt 2.0 air cooled. Having mechanic put a Dokata cylinder head sensor
> under #3 plug, to gauge on dash. What should the temperture be?
>
>
>
> Glen
My 79 'oaf engine was built a la Gene Berg specs wit hreamed out
combustion chambers and spacers under the barrels to get the CR down to
7:1. I think Ray Litz did the port job on them and the bigger valves.
I had a mild cam in it and dual two barrel webers, 44IDF's IIRC. I too
was concerned about head temp and Mr.. Berg said any head temp gauge
costing less than $900 would not give accurate readings. I tried
mounting the VDO ring sensor underthe plug and had trouble with it
shifting around during tightening and moving it under the factory temp
sensor gave really low and un responsive reading. I ended up modifying
things so the ring would fit under one of the copper exhaust flange nuts
on the #3 cylinder(old shcool thinking there, for sure) and with one
venturi per cylinder, I'm pretty sure I was getting as cool a
readingunder load as I was goingto get, especally when the plugs were
reading perfectly. The engine lasted over 100k and I had solid lifters
in it and checked valve adjustments every 3k, but adjust valves maybe 3
or 4 times in that 100k, and once they were loose rather than tight.
Bottom line was that the head temp sensor in that position never read
any higher than 450 degrees, and that was under full load climbing I-24
up to Monteagle/Sewanee TN(8-10 mile climb at about 8% grade) in the
middle of July with 2 full sized canoes on the roof. Whether or not the
number of degrees F was accurate or not, the gauge/sensor reacted MUCH
quicker to loads and head temp changes being mounted there as opposed to
under the plug, and after all, isn't that what we're really after?
Knowing when your gauge gets past point "C" is when you need to slow
down or check for other reasons why it's getting hot. When I'd be off
load going down that hill on I-24, the head temp dropped immediately,
the oil temps lagged far behind, as they should have. I realize carbed
motors don't have ECU issues and that was like 20 years ago, but Berg
made a believer out of me.
YMMV DM&FS
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