Timing - PInging Problem - Team Camaro Tech
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post #1 of 6 (permalink) Old Apr 3rd, 01, 06:05 AM Thread Starter
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I have been fighting a timing problem with my new engine. I am running an MSD distributor with vacuum and centerfuge advance. I also have the MSD 6AL ignition box. I am setting the timing at 8 degree BTDC. I am trying to dial in the distributor. MSD allows you to change the springs and the amount of advance by replacing a small bushing. At low RPM under load I am pinging. Should I solve this by changing the springs or the spacer. Right now I am at 25 degrees total advance with this happening at around 2500 rpm. Has anyone else got an easy solution for dialing this in. Their are infinite settings by changing springs and the bushings.

Thanks Jeff
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post #2 of 6 (permalink) Old Apr 3rd, 01, 02:15 PM
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Try a heavier spring that will slow the rate of advance down and should help the low speed pinging

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post #3 of 6 (permalink) Old Apr 3rd, 01, 06:09 PM
 
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what octane gas are you running? if 87 you might try 92 to see if that helps some
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post #4 of 6 (permalink) Old Apr 4th, 01, 08:53 AM
 
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What amount does the vacum add? I limit the vacum advance to 10 degrees. (If your storebought advance can is something like 17 degrees, then there is your problem.)
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post #5 of 6 (permalink) Old Apr 4th, 01, 09:45 AM
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you might also want to try a adjustable vacuum pot, like crane make's. ping is cause by how much and when the advance comes in.

a part throtle ping is normaly a vacuum advance issue.

IMHO you need between 10* and 15* of vacuum advance. it should start around 5 to 10 in. of vacum and be all in by around 15 in.

i also recomend if you do not run a EGR or other smog stuff to use manifold vacuum.

vacuum advance is what i call a idle timing aid, and a cruse efency aid. ported vacuum is not there till around 30MPH or higher and it is never a full vacuum source. a cruse at say 60 MPH your motor is makeing around 20in of vacuum, but ported only give's you around 8 or 10 in. of vacuum. that is why a vacuum advance pot for a EGR motor is all in by 8in. of vacuum. not as good thing in a performacne motor.

set your mechanical to come in by around 3000 RPM and be in the area of 20* to 25* of advance. set base timing at around 10* to 15* BTDC your traget is around 32* to 38* totale timing at 3000RPM with out vacuum advance conected. you will get anthor 10* to 15* with the vacuum advacne conected at idle and cruse, useing manifold vacuum. for a target totale of 42* to 53* with vacuum advance conected.

manifold vacuum also help's you keep your throtel plate's in what i call the "sweet spot", so you do not have too much transfer port showing and get an off idle stumble or a too rich idle mix. hope this help's ya out.



[This message has been edited by ilbl8 (edited 04-04-2001).]
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post #6 of 6 (permalink) Old Apr 4th, 01, 10:00 AM Thread Starter
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Thanks that is what I think the problem is. I have changed the springs to the lighter springs which is giving me full advance around 2500. At the same time I went from 18 degrees to 28 degrees total advance. I have since dropped from 28 to 25 degrees and it did not help. I am going to try one heavier spring this evening and see if this cures or helps eliminate the problem.
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