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Ignition timing issue on a SBC
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DRR Trophy
Picture of Jason Haley
posted
I'm losing somewhere around 15-20 degrees of ignition timing once I get above 2000ish RPM on my 383.

The ignition is a MSD 85551 distributor and a MSD 6AL-2 box, part number 6421.

I changed the magnetic pickup in the distributor and it didn't do anything to improve it. After that, I found the vertical play in the distributor shaft to be well over .050", so I shimmed it to be around .015", but I haven't tested that yet.

Also, the camshaft thrust is right. This engine was in my car for over a year without this issue and I didn't change anything internally when I put it in my truck.

If shimming the distributor shaft doesn't fix the issue, where else should I look? Borrow another timing light? Try another ignition box?


Slow S-10
Slower Cutlass
 
Posts: 40 | Location: Smiths Grove, KY | Registered: December 06, 2010Reply With QuoteReport This Post
DRR Sportsman
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Flip the pickup wires.
 
Posts: 935 | Location: my own little world | Registered: July 20, 2005Reply With QuoteReport This Post
DRR Pro
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quote:
Originally posted by Jason Haley: This engine was in my car for over a year without this issue and I didn't change anything internally when I put it in my truck.


Engine timing worked correctly in vehicle A, then swapped engine to vehicle B (recently?) and now timing retards when over 2000 rpm?? Did engine timing ever work properly in vehicle B it is now in?
 
Posts: 2503 | Location: 53056 | Registered: December 30, 2009Reply With QuoteReport This Post
DRR Top Comp
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Melonized, bronze or EverWear distributor gear?? Confused

8620 carbonized Billet Steel cam core??
 
Posts: 9398 | Location: Madeira Beach Fl. | Registered: June 12, 2018Reply With QuoteReport This Post
DRR Sportsman
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quote:
Originally posted by BJs Wild Ride:
Flip the pickup wires.


This
 
Posts: 123 | Location: Over here | Registered: November 28, 2007Reply With QuoteReport This Post
DRR Pro
Picture of rusty
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quote:
quote:
Originally posted by BJs Wild Ride:
Flip the pickup wires.


This

this first , then change the ign.


honesty is the best policy,insanity is a better deffense
1.036, 6.16@ 224

 
Posts: 1421 | Location: texas | Registered: February 17, 2006Reply With QuoteReport This Post
DRR Elite
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Agreed^^^
 
Posts: 13522 | Location: NJ | Registered: August 20, 2000Reply With QuoteReport This Post



DRR Sportsman
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Do you have ANY retard chips in the system anywhere. We had a 2 degree chip that was doing eactly the same thing in our dragster with a 7al3 a few years ago. Might want to swap any you have with a new one.


"I am not ashamed to confess I am ignorant of what I do not know."
Marcus Tullius Cicero
 
Posts: 995 | Location: Las Vegas, NV | Registered: April 14, 2004Reply With QuoteReport This Post
DRR Pro
Picture of Goob
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quote:
Originally posted by BJs Wild Ride:
Flip the pickup wires.


This first!

Some timing lights don't work with an MSD. The switch from multi-spark to single spark happens around 3000 RPM so your light may be reacting to the switch.
New vehicle, same timing light, I'd say the distributor pickup wires need to have the polarity swapped. The wire colors don't always match up.


"Despite the high cost of living, it remains popular."
Dave Cook
N375
 
Posts: 1703 | Location: Indy | Registered: November 21, 2008Reply With QuoteReport This Post
DRR Trophy
Picture of Jason Haley
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First things first, thank you for all of the suggestions. I'll be sure to remember them if I have this issue again in the future.

Second, I flipped the pickup wires to the most retarded position last night (what MSD told me to do) and there was no difference.

Finally, shimming the distributor shaft last night solved the problem. I put the distributor back in today and I now have a solid 36° like I'm supposed to.

Thanks everyone!


Slow S-10
Slower Cutlass
 
Posts: 40 | Location: Smiths Grove, KY | Registered: December 06, 2010Reply With QuoteReport This Post
DRR Pro
Picture of Eman
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Great you fixed it. Check the center terminal inside the cap and the spring on the rotor.
 
Posts: 1480 | Location: E TN | Registered: February 13, 2009Reply With QuoteReport This Post
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