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Discussion Starter #1
been having a problem w/ the longroof for a few weeks now, done a bunch of stuff.... still not running the way it should

at speed, mostly at 60+ mph, get a miss for a split second, sometimes sounds like a carb backfire. Like I'm loosing spark for a split second and then back to normal....

run it at least 50 miles per day. sometimes it will only happen once, other times it will do it 3 times in one mile... If I stay on it, probably would do it more, been driving slowly lately....runs pretty good at lower speeds...

so far... pulled the cap, it was thrashed, so I put a new cap and rotor on it. when I pulled the rotor off, saw that the mechanical weights were are thrashed and out of whack (one of the studs that holds them on was broken off and they were all worn bad). So swapped that distributor out for another one I had. (the one I pulled out had about 30k on it, 2yr old rebuilt unit) so I swapped the other one in, put a new set of weights/springs on it, still seemed off, so I pulled it out and reinstalled it to make sure I had it in the right spot.
Seemed to run good, ran it on the freeway, same thing, way better around town, but still a backfire at speed. Fixing the advance weights for sure fixed it low end....

put new spark plugs in also.... and a K&N filter.....

next changed the timing.... had it set at 5-6 degrees advanced, bumped it to 10 degrees.... manual says 6 degrees for 74, 10 for 75, then 6 for 76?

seemed to help again low end, but still get the miss as 60+ mph....???

(67 194 ci six, 75-76 HEI external coil, 2 spd glide, 4 bbl holley....)
 

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Check your total timing and make sure you set it with the vacum advance unhooked.

if that checks out ok, It could be a lean condition at freeway speeds. usually you feel a surging if it is too lean.

Dan
 

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Discussion Starter #3
my light only does initial timing.....what should my total timing be?

I usually pinch the vaccum line w/ a set of vise grips....

Today it did feel like it wanted to take off, but if I put my foot into it that's when it backfires....

I've been running this same set up for a few years now, with no major problems....

always runs rich on the street and real good on the freeway....
maybe upping the timing it's getting a better spark and wants more fuel? already got a 390 holley 4 bbl on it.... I would have down sized the jets if I wasn't so busy/lazy...
 

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Might want to check on the Ign module just to make sure its not starting to go out.


Just a thought

JamesY.
 

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Discussion Starter #5
Might want to check on the Ign module just to make sure its not starting to go out.
only 2yrs old, 30k... took the newer one out of the rebuilt dist. and put it in the old one.... think it would go bad in 30K?
 
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