[Vwdiesel] So many variables, so little time

slatersfb at aol.com slatersfb at aol.com
Wed Dec 14 13:05:42 EST 2005

 Well, there are lots of things to play with. You are correct about cam timing: retard the cam & you will get more power up top; advance & get more bottom end grunt. Be careful to rotate engine by hand before start up to make sure valves clear the piston. One full tooth may be too much. 
Pump timing is matter of feel & sound to me. Some factors I look for when setting up pump are: throttle response off idle should be crisp. On a cool morning - roughly 20 degrees F, engine should require advance knob pulled out to start cold & run smoothly. Accelerator pedal position - should not require that you keep pedal half depressed in order to maintain highway speed. I set my car up for mostly highway driving. Throttle response between 60 & 80 mph should be surprisingly snappy. Pump timing setting as checked with dial indicator ended up at 1.1 mm advance. 
The full load screw I set up to smoke a little at full tilt. I can see it in daylight, but not like a crop duster. Mainly, whatever conditions you drive your car under, it should feel right. It is only a 1.6 liter engine, but when tuned to your taste, it can make you smile. Gina, my 1.6 N/A Jetta consistantly gets 47 mpg US. 49 is the best I ever got on a long trip at about 70 mph. 
Her fuel pump is not original - there is no LDA.
Fuel quality affects mileage and power & changes with the season. Winter fuel starts, but has no balls on the long hills of my commute. Good mileage & power from home heating oil, but not so fluid in winter. 50% WVO in summer got the same mileage & better power up long grades. I buy from fuel retailers who sell large volume & have had good luck that way. SHELL ROTELLA diesel additive helps cold starting a lot. Val says he is getting over 50 mpg with a car like mine. Damn impressive.
Bob in the Entire State
-----Original Message-----
From: hwy9fergs at comcast.net
To: vwdiesel at vwfans.com
Sent: Tue, 13 Dec 2005 19:53:46 +0000
Subject: [Vwdiesel] So many variables, so little time

Bob said
Set it up by the book, and it will probably run, 
but it will run a lot better if you take the time to adjust each aspect to 
standards attained over a lifetime. Granted, this takes more time.

Svend said, 
TIME her and then take her here and I will TUNE 
it   free
of charge----then marvel at the difference,.------If that does not  convince you
  ---    have a nice day.

Guys, I'm all ears.  Bob, I still have your post about your timing numbers, but 
you mention "each aspect" of tuning. Can you be more specific? Svend, I'm glad 
you mentioned in your recent post about still needing to get back to me on your 
actual specs (what the specs ended up after you "tuned" bunny bondo). Because, I 
am still curious.  I hear people talking about getting 50 mpg or better with 
these 1.6 IDI vw's, but my real world experience, driving my 91 ECO turbo Jetta, 
(AC, power steering) has me getting around 42 on my work commute (mixed driving, 
some mountain road, some freeway).  I get about 37 MPG on a long trip at 75 MPH. 
I think that's pretty damn good. Can it be better?  Well------you tell me.  
People throw out mpg numbers alot of times, but don't get very specific about 
the conditions. Sure, I don't doubt my car could get 50 mpg or better just the 
way it's set up (tuned by the book). All I need to do is drive at 48 mph with a 
25 mph tailwind, and I wouldn't be surprised. Hell on a long downhill, I'd 
probably get 70 mpg.   Unfortunately, in my world I have to be realistic.  How 
many things can you effectively "tune".  OK, pump timing you can play with. If 
your pump is a little weak, you can bump the working pressure up a bit from what 
I recall in an earlier post (Hagar's) Any one ever play with their cam timing?  
I've heard that if you retard the cam timing, you will pick up some horsepower 
(at the expense of low end grunt) and if you advance the cam timing you improve 
the low end torque (and lose a little HP). I don't have any information on how 
many degrees of timing you would play with on that, or how it might affect 
mileage. My cam is set at stock spec.  Over all, what I have concluded is that, 
once you get one of these engines properly bolted together, there aren't really 
that many things you can play with other than---injection pump working 
pressure/timing, cam timing, and maybe valve clearance on the mechanical 
engines. I know you can adjust turbo pop off and waste gate stuff, but I'm not 
talking about full throttle stuff right now. So at this point, what I would like 
to know is, assuming you have a starting point at factory specs, what do you 
consider adjusting and which direction to you go in your adjustments to improve 
mileage?  Maybe go from 1.00mm to 1.05mm on the timing?  My engine sounds 
awfully marbley when cold as it is.  Wouldn't advancing the timing make that 
worse?  If you retard the timing, doesn't that quiet the marbles down at the 
expense of mileage?  I haven't ever checked my working pressure in my pump, but 
I'm considering trying to put the bits together to be able to accomplish that.  
OK guys, the ball is in your court.  How many of these variables have you 
acually played with in your "tuning"?  How about "real world" mileage specifics.  
I'm keeping an open mind.  Flyboy Doug.   
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