MFPvet
Member
Posts: 19
Loc: Le Roy, NY
Reg: 06-03-05
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09-10-12 10:47 AM - Post#2268372
I've got a 1980 vette with 290HP crate engine and HEI distributor. I installed a Mallory Hyfire 6AL ignition box and a few things are weird. First, the timing showed an additional advance of nearly 50 degrees after installation. So I reset the timing to 14 degrees base. Then, when driving I get an occasional hesitation like misfire. Does not happen at idle. Any body have experience with these boxes. I understand the principle (I think) so the timing change does not make sense.
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55chevy383
Senior Member
Posts: 1278
Age: 44
Loc: Noble, Ok.
Reg: 12-08-05
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09-10-12 06:24 PM - Post#2268518
In response to MFPvet
Double check your grounds and make sure they are good.
Phil
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 50hotrod
"2nd Year" Silver Supporting Member
Posts: 364
Age: 56
Loc: Wisconsin
Reg: 07-25-11
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09-10-12 11:45 PM - Post#2268570
In response to 55chevy383
You posted MSD ignition issue and wrote "installed a Mallory Hyfire 6AL".
If it's a Mallory you installed that's your problem. I just went round and round with Prestolite (Mallory). I will tell you from experience do not send the unit in for repair.
You will only be told "nothing is wrong" Take it back where you bought it and get an MSD!
I'm not in the habit of bashing company's but Mallory cost me more in shipping back and forth and wasted time triple checking everything on my car that I knew was right from the beginning they deserve it. I hate to see someone else go through the same senseless BS.
Well, you know what's wrong with the world today
People done gone and put their Bible's away
They're living by the law of the jungle not the law of the land
"Simple Man" By Charlie Daniels
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GottaSS
Forum Newbie
Posts: 46
Reg: 07-16-12
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09-11-12 07:33 AM - Post#2268623
In response to MFPvet
Are you using a dial back timing light? Some dial back timing lights do not work well with the multi spark MSD 6AL. Check your timing with a non dial back light and see what you have.
You also need to know what stop bushing you have in the distributor. If the stop bushing you have is allowing too much mechanical timing advance yuou need to replace the bushing. You should never exceed 36* total timing with the vacuum advance disconnected and plugged.
A good timing setting for the MSD HEI distributor and control box would be 15* base, 21* stop bushing, a light silver and a light blue spring would give you 36* total timing, all in by 2,500 rpm. Vacuum advance has no role at WOT but a 10* vacuum advance would be helpful at idle.
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MFPvet
Member
Posts: 19
Loc: Le Roy, NY
Reg: 06-03-05
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09-12-12 06:35 AM - Post#2268890
In response to GottaSS
I do have a dial back light, but that's not how I determined the timing was off. I installed the 6AL unit without adjusting the distributor. When I started it and test drove, it was obvious the timing was way off. That's when I set it correctly to almost the same specs you quoted. Since the cap and rotor can only go on in one position, it seems the installation of the Mallory unit caused the timing change. It shouldn't do that from what I know.
I had sent this unit back previously and was told it was fine. I guess that's why we don't see them under anyone's hood.
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50hotrod
"2nd Year" Silver Supporting Member
Posts: 364
Age: 56
Loc: Wisconsin
Reg: 07-25-11
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09-12-12 08:48 AM - Post#2268932
In response to MFPvet
I had sent this unit back previously and was told it was fine. I guess that's why we don't see them under anyone's hood.
Yup, I hear ya. Cut your losses now and get rid of the Mallory.
Well, you know what's wrong with the world today
People done gone and put their Bible's away
They're living by the law of the jungle not the law of the land
"Simple Man" By Charlie Daniels
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MFPvet
Member
Posts: 19
Loc: Le Roy, NY
Reg: 06-03-05
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09-13-12 06:46 AM - Post#2269226
In response to 50hotrod
Couple of quick followup questions:
I'm going to dump the Mallory box. It's too temperamental and I have no confidence in it being able to get me home. Is an aftermarket HEI module a good option instead of a stand-alone ignition box? I see some with rev limiters (I have a manual tranny). What I liked about the multiple spark box is that it gave better fuel mileage (when it worked). A hotter spark module may do the same.
Also, the ignition boxes gave the option of using a grounding wire as a kill or security switch. Nice anti-theft feature. If I go back to a traditional HEI module, where's the best place to cut in a security switch. I imagine it would be to the hot wire going to the coil (B+) but I'd like to confirm it before I screw something up. Thanks.
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