Looking for help with MSD system
Thread Starter
Heel & Toe
Joined: Jul 2006
Posts: 21
Likes: 0
Looking for help with MSD system
Installed MSD in 72 vette 454. Car runs great as long as I have the vacuum advance plugged. but once I connect the vacuum and increase the rpms ever so slightly the engine starts poping and backfiring. Car is set at 8 degrees BTDC as specs call for. I have all advance coming in around 3000 - 3200 rpm. and have tried all different set ups from heavy springs to light springs from larger bushing to smaller bushing with the same results. I have even tried different vac cans but keep getting the same thing with no luck once vac is connected. Has anyone had this problem and if so what can be done to solve it. I contacted MSD but they were of little help. With the vac disconnected the plugs foul up very quickly. Any help would be much appreciated.
Mark
Mark
Safety Car
Joined: Jun 2005
Posts: 3,841
Likes: 0
From: Inver Grove Minnesota
Installed MSD in 72 vette 454. Car runs great as long as I have the vacuum advance plugged. but once I connect the vacuum and increase the rpms ever so slightly the engine starts poping and backfiring. Car is set at 8 degrees BTDC as specs call for. I have all advance coming in around 3000 - 3200 rpm. and have tried all different set ups from heavy springs to light springs from larger bushing to smaller bushing with the same results. I have even tried different vac cans but keep getting the same thing with no luck once vac is connected. Has anyone had this problem and if so what can be done to solve it. I contacted MSD but they were of little help. With the vac disconnected the plugs foul up very quickly. Any help would be much appreciated.
Mark
Mark
Thread Starter
Heel & Toe
Joined: Jul 2006
Posts: 21
Likes: 0
yes,the timing was set at 8 degrees and running fine. Did put in new balancer. when I did this over haul thing. I had just dropped in another HEI (not MSD) dist that a friend had and it works fine w/ vac connected.
2nd Gear
Joined: Apr 2008
Posts: 2
Likes: 0
try setting your timing back to about 4btdc, then attach vacume to a ported vacume on carb. and readjust carb accordingly. I did this on a 350-350 and it worked out fine. for some reason when full vacume is attached, you get the popping through the carb and exhaust. I think the factory dist advances to quick and with the msd box, a lot more voltage is traveling through the system
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