another switch box question

[baycrabber1]

1987 black max 150 miss from idle to 2000rpm. been all thru the carbs there great. compression is 115 across the board.timing is dead on , zero pointer dead on. did all the test with a dva all voltages were good and the book says if the readings were good to replace the switch boxes,is it possible to have bad boxes that only fire GOOD on 5 and 6, cyls 1thru 4 dont change it much when you pull the wires off with it running. and is there a test to check the boxes

[gmacrae]

if you reckon your stator voltages look good, have you checked the switchbox grounds? and all other grounds for that matter. What about trigger coils? Mine had a dodgy trigger causing one or two pots to fire bad at low rpms (replaced it with a new CDI part) - not sure if it would cause 1-4 to miss though... Are you able to borrow some switchboxes from someone? New CDI switchboxes are pretty well priced, and better than merc ones according to most people, but if you can borrow some that'd be great. Maybe post up your location and a forum member might be able to help you out with some loan switches.

[baycrabber1]

im in harford couty md just outside of baltimore. all my readings are within spec stator,trigger, switch box bias. can the switch boxes be tested?

[gmacrae]

the only way i've heard of people spotting switchbox problems is by spotting random out of time firing (way advanced or way retarded) or double firing, just by using a timing light. I'm no engine tech tho so don't take my word for it, hopefully one of the pro's will chime in...

[baycrabber1]

ty maybe a tech will respond