FIRST TIMER- using a performance distributor
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Junior User
Joined: Apr 2009
Posts: 71
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From: South Texas
FIRST TIMER- using a performance distributor
I finally install the mallory unilite distributor that does not need an ignition control box on my 72 with the 390. I set it up at 12 deg as specs required for OEM and it backed fired lightly through tail pipe and vacuuum was at 5 steady. I advanced the timing to 26 deg and vacuum shot up to 12 steady and it no longer backfires and it runs great. Spark plug is set at .35 and the inside of distributor allows for adjustment of the advance curve from 14-28 degrees. I left mine at 26 deg as it came out of the box. Is this normal for a performance distributor (the 26 deg at the crankshaft)? 
Tuned
Joined: Dec 2004
Posts: 340
Likes: 8
From: Rock Hill, SC
Mine was for a small block, but it still ran 6-10 degrees at idle. Are you checking it with the vacuum line unhooked? It will read higher with the line connected.
I would also look into a voltage protector that Mallory makes for that system that protects the module from high voltage spikes. I went through three of them before anyone mentioned there was such a thing. It's about $60.00 and should be recommended by the people that advertise the system. I don't think most of the speed shop guys even know it exists. Bob Walker from Hemi Hot Heads told me about it at a Good Guys rod show and my speed shop here in town said they had never heard of it. He looked in the catalog and said well son of a gun there it is.
I would also look into a voltage protector that Mallory makes for that system that protects the module from high voltage spikes. I went through three of them before anyone mentioned there was such a thing. It's about $60.00 and should be recommended by the people that advertise the system. I don't think most of the speed shop guys even know it exists. Bob Walker from Hemi Hot Heads told me about it at a Good Guys rod show and my speed shop here in town said they had never heard of it. He looked in the catalog and said well son of a gun there it is.
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Junior User
Joined: Apr 2009
Posts: 71
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From: South Texas
I did get one surge protector, but only after I received the distributor and read the instructions, I found out that the type of distributor I got needed one. The sales person never suggested I needed one, so another week of delay. I also had to get a mallory coil as suggested by the instructions, next month it will be larger spark plug wires. Its getting expensive, but the outcome is priceless
. I drove it all day today and no backfire and temp stayed at 180. I connected the vacuum gage to an extra intake vac line and it is a steady 12. At 8 deg it runs rough so I kept on advancing to get the highest vacuum and it ended at 26 deg. I am completely puzzled.
. I drove it all day today and no backfire and temp stayed at 180. I connected the vacuum gage to an extra intake vac line and it is a steady 12. At 8 deg it runs rough so I kept on advancing to get the highest vacuum and it ended at 26 deg. I am completely puzzled.
Tuned
Joined: Dec 2004
Posts: 340
Likes: 8
From: Rock Hill, SC
Is your distributor vacuum advance? Do you have an aftermarket cam? On your engine I am not sure what the total advance should be, but idling at 26 degrees sounds extreme. On a smallblock 32-34 degrees is plenty. I know the FE engines require a little more.
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Junior User
Joined: Apr 2009
Posts: 71
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From: South Texas
Yes I do have a Crane cam, mild, I currently don't remember the grind on it though, I replaced the cam when I rebuilt the engine in 2000 At the moment it still has the stock intake toped of with a Holley 4 barrel 600cfm carb. The Mallory I am using does have a vacuum advance. I know that as I started to advance the dist by rotating it slowely, I got 15 on the vac gauge, but the degrees was way past the scale on the balancer, so I backed it up to 26. I did not take it out for a test drive though, so I don't know what it would of done. I also wonder if it has something to do with the gap in the spark plug. Currently they are gapped to OEM specs of .035
