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Old 07-28-2004, 03:59 PM
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Originally posted by DoubleVision
I run a road demon Jr. 625, it`s been a good carb, I did have to clean out the idle circuits though. I had spoken to many techies on the phone, and not only at BG, but other places as well, they all recommened high spark timing, I had my timing set as high as 16 degree`s and it was still a dead player slug out of the hole, but none of them asked, or ever mentioned, which vacuum port the vacuum advance is suppose to be connected at, I had it connected to a ported source, or one that pulls vacuum off idle, after a recommendation from BOBCRMAN, I set it at 12 degree`s BTDC with vacuum advance disconnected and plugged, then connected it to the manifold source or full time vacuum, I rechecked the timing with it connected, the timing at idle was right around 24 degree`s BTDC, I drove the car and what a huge difference, it has outstanding low end, and good midrange, something it never had before, vacuum advance at idle is needed since the idle is lean and usually off idle is lean, leaner mixtures burn slower than do richer mixtures so more spark timing is needed. In one case where we were running a 400 with 6 inch rods and a comp solid 260 duration cam, we set the base timing at 20 degree`s, since we used such a big cam vacuum advance can`t be used, so we made up for the lack of it just by advancing base timing more.
I am in the same boat vaccum wise. Seems the logical answer to this (assuming theres nothing wrong with the carb) is to head towards a programmable ignition system.
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