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Make sure the carbs are properly balanced and synchronized. This is
generally done at an engine speed of 2000-3000rpm, not at idle! You may
want to adjust your valves again to make sure they are at the proper gap.
>From what you are describing about her shaking in the morning for a bit
until she's warm suggests may have an ignition problem. I had a similar
problem until I upgraded my ignition system. Here's the scoop:
When you start the car in the morning the power in the electrical system is
low. Starting the car means the ignition is getting its power from the
battery, which is also supplying the starter. Ok, if you add to this any
fouling on the spark plugs, no matter how little build up there may be,
this fouling robs the spark energy from the spark plug and the spark plug
doesn't fire or the spark it creates is very weak. A weak spark may or may
not ignite the fuel mixture and if it even does the burn will not be much
in producing power like a normal burning would do. Once you get driving
and the generator/alternator gets juice pumping in the system the ignition
has more power to use. Also, the faster the engine turns (rpm) the *less*
energy is required to fire off the fuel mixture. Unfortunately, every
ignition system found in every stock car on the road is built upon
compromise. This means a bunch of give and very little take, so the
ignition system is designed to get you by and nothing more.
What can you do to help your ignition system? Upgrade your ignition system
to a computerized ignition system like I did using Jacob's Electronics! We
know how fuel injection is better than carburation, well, the same is true
for a computerized ignition. But if $310 is too much and you'd rather
stick to the stock components here's what to do:
Make sure your ignition wires are in very good condition (no cracks) and
that they are not excessively rubbing on anything (use those wire
separators!). How to check spark plug wires? Go to a place where there is
no light (if you use a garage make sure you have a hose directing the
exhaust outside!!!). Bring the engine around 3000rpm and look at the spark
plug wires (okay, their general location in the dark :p ). If you see a
blue corona (glow) then they are bad, replace them. If there is no glow
then LIGHTLY brush your fingers on or *very* close to the spark plug wires.
If you see any glow around your fingers/wires then the spark plug wires
will need to be replaced soon, but can wait for a short time. No glow
whatsoever means the wires are good.
Clean the distributor cap, inside and out. Crap on the surface of the cap can
create a path for the electricity to leak away from the spark plug wires. I
witnessed this on my stock system. A spark went from the #1 terminal across the
outside of the cap, jumped to the stock fuel line, then ended on the mechanical
fuel pump body. Yeah, it spooked me too!
All my experiences with a bad coil are as follows: It's bad, it won't work.
This means if your coil is working then don't mess with it. And by all means
use only a Bosch coil, never some other replacement coil. I speak with
crystal-clear experience! Use Muir's (The Idiot Book) suggestions for testing
the coil if you think the coil could be going bad.
Use Bosch spark plugs, preferably the Platinum type. These require less energy
to create a spark so your chances of a misfire are lower. You will get some
gains in gas mileage and power (torque). Something I suggest every one should
do if they can is to index their spark plugs. This allows the spark to face the
fuel mixture during the compression cycle and allow a better chance of igniting
it. Gains from doing so would be improved gas mileage and power since the
mixture is burning more completely. Using indexed Platinum plugs may allow you
to open the spark plug gap a little. Try .005" increments until you notice the
performance drop, then close the gap back one step (.005") and you'll be at the
right gap. A larger spark plug gap is good since it allows more of the fuel
mixture to contact the spark and it increases the burn radius. However, a
larger gap requires more energy for the spark to cross so make your gap
increases small because the stock system doesn't put out a lot of power.
Remember, though, that you should change the spark plugs when the engine is cold
(or very cool) to avoid striping the spark plug hole threads in the engine
block. Be careful!
Toby Erkson
air_cooled_nut@pobox.com
modified '72 VW Squareback 2.0L
stock '75 Porsche 914 1.8L
______________________________ Reply Separator _________________________________
Subject: Rebuild 1600 engine troubles...
Author: type-3-errors@umich.edu at SMTPGATE
Date: 12/23/96 2:24 PM
Hi everybody,
LAst Saturday was THE day. We finished tuning my rebuild 1600 and I drove
for about 20 miles for the first time (with this engine). It ran great, no
problems, just a little shocky in the beginning.
First I want to tell you that the engine is tuned in neutral gear ( of
course ), and it runs fine that way, no shocking, stuthering or anything, it
runs smooth.
But here is the problem. In the morning ( cold ) the engine starts
immediatly, but I have to push the accelarator a few times to prevent it
from stalling ( pretty normal, no ? ). When I start driving then, the car
won't accelarate properly. It drives all shocky and shakes. I get the
feeling that the engine wants to accelarate, but can't do so. This
disappears after driving a few miles. Then the engine runs smoother ( in
gear ), but not perfectly. Also when I brake with the engine, it gives this
"puffy" sounds, is that called "backfire" ( sorry if this might seems as a
silly question )? If it is backfire, what can I do about it ? I don't want
to drive around to long with an engine not runnin,g smoothly, because I
spent nearly 2000 $ on it. And I'm just a student, so my financial
sitiuation isn't too bright at the moment.
...