Tuning on the off-week

Suspicious of missing out on some straightaway speed, I sought the advice of one of the experienced club members.  We discussed several ideas to explore but settled on doing a leakdown check on the engine.

The process is pretty simple.  You take the cam out of the operation by removing the rocker arms.  This ensures that the valves stay seated (closed) during the test.  Compressed air is introduced through the spark plug hole and we check to see where it tries to get out.

It is normal for the rings on the piston to leak some as they do not form an airtight seal but you should not hear air coming out of the exhaust pipe or the carburetor throat.  During the test on our engine, we could hear a small amount of leakage through the exhaust.  Although it is was detectable, my friend assured me that it was insignificant on the track.  What else could I try?

Spark plugs? I have been running a conventional plug like the one pictured here.

This has the standard ground and I was diligently keeping the gap set properly.  No surprises here.  What about this stuff I read in the forums about a great racing plug for the Animal?  I decided to give it a try.  It has a cut back ground to increase the exposure to the spark.  This is the plug I had in when I visited my friend for the leakdown test.

My friend pulled out yet another upgrade to the plug.  It is radically different and offers even more exposure.  This is similar to what is used in some aircraft engines.  Apparently, it is legal to run so, we will give it a try.

Another upgrade he recommended was a larger air cleaner assembly.  This picture is a side-by-side of the new verses the old.  Obviously, the new has more surface area and will have less restriction.  With the larger restrictor plate, he claimed that this could make a difference for us.  The elongated base also acts as a semi-velocity stack to leverage the inertia if the intake air to "pack" molecules in the engine.

Finally I replaced the drive chain as I understand an old chain can increase drag.  With the stretch between rollers, the rollers don't fit nicely between the teeth and take slightly more power to engage.

With the new air cleaner installed I found it interferes with the right rear tire.  I may have to get creative but for now, I'll have to run the old air cleaner.

I'm again on-shift for the next race but may still be able to get a friend to swap.  I'm looking forward to see if any of this makes a difference.