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Subject:Dyno testing and timing changes was Re: 85 1.9L timing mark - once and for all
From:Robert Donalds
Date:Thu, 17 Jan 2002 10:06:00 -0500

Rio and fellow vanagon types 
As you know I have been testing engines on the Chassis dyno. I finally got my 84 2.1 big valve engine running correctly and tested it this past Tuesday. I four pulls (tests) and made one change after the first two pulls to see if more timing made more power and it did. let me recap I have installed a 2.1 big valve engine in my 84 camper 
I kept the digijet fuel injection system and left the stock dist and pulley. when I changed the timing from the stock setting of 5 ATDC to about 4 or 5 BTDC I found two things first the dist tended to kick in more advance due to the increase in RPM if I went past this point. by this I mean the timing moved more than I was turning the dist. I did not check but I think the centrifugal advance was engaging. the second thing I found was that the engine made about 10 % more power throughout the power range Keep in mind this is a 2.1 engine in a 84 with digijet. 
I need to be clear that all the old time tuners say not to believe any flash reading on a dyno with changes in timing!!!!!! I have found that changing the timing makes the engine run hotter this can take time and might only happen under constant loads (highway driving) hotter engines CAN loose power and melted pistons can be a result  
    At this point I am still going threw the #s for all the tests and will offer my finding when I am confident that I have the correction factors for the different days of testing correct and the HP #s plotted on a spread sheet with the torque included.
Bob Donalds
http://www.bostonengine.com 
As always 
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