Topic: Engine popping thru carb

[Denib1986]

I got a 18hp vanguard with big valves ported heads ec big bore carb wen I bring the engine to a high idle some were around 3500 rpms the engine spits and pops back thru the carb it almost acts like a rev limiter but I no it's not I got new coils arc fly wheel new plugs new cam and tappets timing is at 30 valveless lash at .004 I can't seam to figure it out any idea thanks in advance

[Kokamo]

Check for:

~Intake manifold/carb leaks
~Spark plug gap (around .030")
~Ignition coils to have an air gap of no less than .040"
~Double check timing with a timing light
~Use timing light to see if ignition is cutting out or being erratic
~Perform a leak down test to be certain your valves are sealing

You did not specify type of cam, but if it's adjustable, are you sure it's timed correct?

This could also be a lean condition in the carb. Be sure it's clean...all jets and air bleeds to be free and clear.

Also, while it's at idle, spray a flammable liquid (carb cleaner) around all gasketted joints all along the manifold.

I'm not %100 sure of the VG motors, but they may have a diode between the coils. disconnect the kill wire completely off the coils and see if it still does it.

Hope this helps,

~Joe

[Drifter]

Quit buying popcorn gas