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timing question help

789 Views 2 Replies 3 Participants Last post by  Jerry70
I have been fine tuning my motor forever. I put a moroso kit in my msd upgraded hei. I used the middle springs that don't start providing mechanical till like close to 2000 rpms. I had to do this because my idle was 1000 or so and regular springs would flutter the mechanical in and out making timing and idle very off. My issue now is I shot in 36 total at 3000 rpms with the vacuum advance removed and plugged off. My base is like 25 or so now? I have read and seen 18 base is on the high side but I have had nothing but issues getting my ride into those ranges. The car seems to run ok but I suspect it has to much advance at idle. It loves advance with the 292 530 lift cam but it appears I am not doing something right. Any ideas or kits to grab a better timming curve. I do have to much vacuum advance right now which is around 15 and will trim it down soon.
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Are you sure that the timing is all in by 3,000 rpm? If the springs are heavy enough that centrifugal isn't starting until 2k, I wouldn't expect total to arrive until around 4-5k. Keep in mind that changing springs (unless they're REALLY heavy) won't change the amount of centrifugal, only where it starts and ends. Big cams definitely like lots of initial and one way to get it without the usual ill effects is to use manifold vacuum for the vacuum advance with a B28 canister. The B28 fully deploys at only 8" vacuum so you shouldn't get the timing variation (and the resulting idle variation) the other cans would cause. In most cases, the increased idle timing permits a lower idle rpm, which in turn can reduce the chances of run-on that's common with high idle speeds.
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