Clone Timing Mark/ Trigger Point

rodv46

New member
Just throwing this up as a general reference, these pics were available separately on the old Bob's in various posts.
Of course, the use of a timing light to determine your actual trigger point is preferable as they do vary from wheel to wheel but if you don't have a light these pics should get you in the ballpark. The flywheels are ARC 6619, King steel, and stock clone.


 
Last edited:

PiMotive

New member
The top right is where my ARC wheel hits while turning with an electric drill.
However, when I started the motor and revved to (I guess) 4,000 rpm, the timing retarded about 2 degrees.
Makes me wonder where the timing recommendations from cam cards come from.

Anyone from the cam industry like to weigh in?
 

Racer14sl

New member
So this is approximately where the spark happens with the ARC 6619 flywheel? Looks like the coil is centered over the magnet?
 

Bruce Fowler

New member
All Clone and Honda ignitions retard at higher RPM's. The newer the ignition the less it retards, it's built into the coil. The problem is that if you over advance the ignition at idle it puts a huge stress on the rod and after 30 years of testing using too much ignition timing is the biggest reason for rod failures.

I have built engines with 34* to 38* timing with a stock rod in the engine but they were basically built around the oil that was used. You do not over rev the engine 5300 to 5500 RPM and Redline 40 weight, but it would run all day long and it had huge midrange torque and ran 4 to 6 teeth lower than anybody else.

Bruce
 

JPR57

Member
So this is approximately where the spark happens with the ARC 6619 flywheel? Looks like the coil is centered over the magnet?
You will probably need to spin the engine a little faster than an electric drill will spin, we use an electric motor on a run-in stand that is geared to spin at appox. 2000 RPMs. If the flywheel has a date code of 2013 or later it should fire as the leading edge of the magnet is in line with the right hand edge of the coil, just like the old tech procedure. However, we have also found that some coils will fire a little different than others, new and old.
 
Top