This isn’t a fuel issue I know it’s ignition.
I keep thinking it’s the crane box but what’s throwing me off is how this missfiring clears up once I take away the vacuum advance.
the vac can does three things, adds timing/shifts RF/increases reluctor gap. Are you saying the problem completely dissappears when the can is capped? something might be loose inside the dist that is being moved when the can shifts. I would cap the can & bump the timing up to where it is when the can is operational & see if it straightens out (grab your dialback). You're sure the RF is close enough when the can is deployed? iirc you said the reluctor gap does not change when the can is pumped up (it changes-gets wider on a regular dist) not sure how this dist is getting around that but it is a good thing). if you duplicate the timing & that ain't it then it has to be something in the dist functioning. (& this is a steady 2500+ miss correct?) EDIT & the can has no vac leak?
Can does not have a vac leak, I have checked the air-gap with and without vacuum advance while holding the distributor in my hand and applying vacuum to the vacuum advance with a mighty vac.
But when it’s in the engine and spinning at 2500 rpm it’s possible it looks a little different then how it looks in my hand.
Someone had mentioned that maybe the oil pump drive bushing could be wiped out causing the inconsistency in timing at 2500.
And it is a steady miss at 2500 that’s affecting every cylinder.
I will cap the vacuum and bring the distributor timing up to 43-44 degrees where it is when vacuum advance is hooked up at 2500 rpm and I’ll bring the rpm up and check every cylinder with the light and report back.
Since it’s chiristmas weekend I’m not sure when I’ll get to it but I’m gonna try ether today or tomorrow or Monday.
