I have good spark out of #'s 1 and 2

but 3 & 4 come and go

what are the possible causes?

coil test good

module test good

Cap or rotor? Wires?

Bad ground...

Are you using anti-seize on your plugs?

no

should I?

NO! Antiseize causes bad spark plug grounds..

You may also have a cracked dizzy cap crossfiring between terminals.

cap looks good, no crack that i can see

tranny ground is on and clean

I know I have read that powder on the fan housing can lead to poor grounding, but i did grind off he powder where it attaches to the engine

what can I do to "add ground" ?

Run a ground straight to the battery.

Is this a used or new dizzy? did you buy it from me?

bought it from you

over a year ago, but first fire up 2 days ago

We'll pay shipping and install it into an engine here to troubleshoot and repair if need be..

This is why we dyno every single one now.. Thjey all run for 20 minutes before leaving the shop... Yours was before that was standard policy.

Do you really think the issue is with the dist. ?

I'll add the battery ground tomorrow and see if that solves it

Rotor seated on dizzy shaft all the way?

I'm curious what would happen if you swapped the plugs wires from cylinders 1 and 2, with 3 and 4. Note a difference? Then swap plugs the same way. I'd just want to rule out it wasn't either the plugs or wires before ruling it is the dizzy.
I just troubleshot a cross-firing issue with an HEI and some brand new 8.5mm silicone plug wires. Who wouda' thunk?
Rerouted the wires, no more problems.

Oh, and best of luck.

so...what does anti-seize good for then jake?

Anything except spark plugs.

why do people feel the need to put it on spark plugs then? where did this start? is it EVER good to use on plugs outside of the aircooled world?

many mechanics suggest using it to keep spark plugs from getting stuck (corroded) in the head. At least on water cooled cars. Problem is that many people put on too much, and it goops on to the arcing bits.

I have always used a little anti-seize on the threads of my plugs, and a little dielectric grease on the insulator to keep it clean under the plug wire boot. I always be sure to make positive that there is no grease or anti-seize on the conductive bits of the plug, and never had a problem.

I won't use it on the 914 since it does not seem to be the reccomended thing to do.
Zach

Milk of Magnesia is the real trick.. Its a great anti-seize that doesn't effect grounding.

i have a big bottle of that stuff in my garage jake. you are correct on it working wonders. and it makes my insides happy after seeing the shit work the P.O. did on my car! it's WIN-WIN!