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Hello! Sam here with JBugs.com. In our last video, we started up our 1800cc stroker engine for its break-in run. It went smoothly and we ran the engine for 15 minutes to get the cam and the lifters are worn in together.
Now that the engine had
cooled off a bit, we pull off the valve covers so we can make sure everything
is as it should be. The first thing we see is that the end bolt on one of our
rocker assemblies has come off. Fortunately, no harm was done so it's
reinstalled and tightened. We double check that the three other end bolts are
tight then the valve covers are reinstalled. We aren't concerned with the valve
covers leaking a bit as we will pull them off again in another 15 minutes of
run time. The oil return adapter bolt is tightened a bit more and we start the
engine up again. We want to run the engine for another 15 minutes for a total
of 30 minutes before we change the oil for the first time.
While the engine is
running, we can dial in the carburetor. With our timing light, it's very easy
to see the adjustments at the carburetor effect the RPM of the engine. The
tuning can be done, and some people prefer, tuning by ear while listening for
the RPM change. We first set the idle mixture screws to the best lean idle by
turning the mixture screws in until the engine starts to stumble. We turn the screw
out, a quarter turns at a time. The RPM should increase and the engine will run
smoother. We continue turning the screw out until the RPM drops or the engine
begins to stumble again.
Next, we turn the screw
back into the point where the engine ran its best. This is usually the highest
RPM point or where the engine sounded the smoothest. Both of the idle mixture
screws, the one at the face of the carb and the one against the fan shroud, are
adjusted the same way. Both are adjusted before the idle screw is adjusted. Once
the mixture screws are set, we can set the idle screw at the carb linkage and
adjust it until the engine idles at about 850 to 900 RPM.
With the carburetor
tuned, we'll go back and double check the timing. [The] distributor clamp is
loosened and we hook up a timing light. With our timing light advanced to 30
degrees, we point it at the crank pulley at the split in the case. The engine
is revved up to about 3000 RPM and we look for top dead center to show up while
slowly moving the distributor. When it does, the timing is set and the
distributor clamp is tightened down.
Now we can run the
engine for another 10 minutes or so to complete our initial break-in run. During
this run, we don't like to let the engine sit and idle continuously so we run
through periods of revving and idling. This will ensure that the piston rings
don't wear the cylinders at any one position. While we are running the engine
we noticed that if we accelerate the engine slowly, the RPM increases without
hesitation. However, if we accelerate the throttle quickly, the engine will
backfire a bit before the RPM increases. This indicates a lean running engine
so we need to richen up the carburetor by installing larger main jets and
possibly larger idle jets.
After we run the engine
for another 15 minutes, we turn the engine off and roll it back inside. Once
the engine had cooled down a bit, we pull the sump plate off slightly to drain
the oil while looking for any large debris. The oil looks as it should and we
can see very small particles that should be expected from running a new engine.
With all of the oil drained, the sump plate is removed completely along with
the gasket. We pull the oil pick-up off remove and clean the screen which has
some gunk and debris on it. The oil passages inside the engine most likely had
some old gunk that didn't get flushed out completely. The screen did its job
though and once it’s cleaned it's reinstalled on the pick-up tube and pushed
into place.
A new sump plate gasket
is installed and followed by the new sump plate. The engine is refilled with
oil. We pull off the valve covers and turn the engine over to number one top
dead center .We check and adjust the valves. The other three cylinders are
checked and adjusted as needed. New valve cover gaskets are coated with copper
RTV silicone and set into place on the valve covers and the valve covers are
reinstalled.
All the oil that leaked
earlier is cleaned up and we'll take a break here until next time where we'll
pull the carburetor off, rejet, reinstall and retune it. While you're waiting
for that video though, check out some of our other videos or stop by JBugs.com
for all the parts you'll need for your vintage Volkswagen.
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