Ignition timing for 454 /w 177 B&M supercharger
06-11-2009, 08:50 PM
#1
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Ignition timing for 454 /w 177 B&M supercharger
What should the timing be set for, basically 525sc motor with Mallory distributor with pertronix conversion with MSD 6A box. What rmp do i set base timing and what rpm for total advance?? THANKS
06-11-2009, 09:21 PM
#2
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As per the Merc manual, the 525 SC is 35 deg BTDC at 4500 rpm.
So simply subtract your advance from there to get base setting.
PS: timing at idle is (19deg BTDC w/ firepower)
(13deg BTDC w/ t-bolt)
Darrell.
So simply subtract your advance from there to get base setting.
PS: timing at idle is (19deg BTDC w/ firepower)
(13deg BTDC w/ t-bolt)
Darrell.
06-11-2009, 09:32 PM
#3
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Looking at a spark advance table in the Manual it also shows this:
T-bolt IV:
Initial: 13 deg
Module adv: 22 deg
Total adv: 35 deg
Firepower:
Initial: 18 deg
Module adv: 16 deg
Total adv: 34 deg
Hope this helps out.
Darrell.
T-bolt IV:
Initial: 13 deg
Module adv: 22 deg
Total adv: 35 deg
Firepower:
Initial: 18 deg
Module adv: 16 deg
Total adv: 34 deg
Hope this helps out.
Darrell.
06-11-2009, 11:54 PM
#4
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Stock 525SC's only have 7.5 to 1 pistons and can run more timing because of lower CR. Based on 35* total, I would retard timing 1* for every .25 point of compression more than 7.5 that you have. That is asssuming you are running about the same 5.5# of boost as a stock 525SC.
06-12-2009, 06:26 AM
#5
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according to weiand you want no more than 26 deg total, need to set the dist with little to no advance, with low compression starting not a issue, a locked dist will help clean the idle up if running a decent cam...Rob
