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Old 08-18-2002, 09:13 AM
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Red face 66 Chevelle pinging question...help?

I am hoping someone can help me figure out what is causing a noise in the top end of my motor.

I have a 66 Chevelle with a 427 .030 over with 12/1 forged pistons, plasma rings, manley rods, steel crank, Reher Morrison BB2 heads, Lunati Roller cam (685/692 lift 269/276 duration at 050 tappet lift) roller lifters, roller rockers, stud girdle, electric water pump, barry grant fuel system, victor intake, Carb Shops 1150 with 95/97 jets, MSD 7AL2/ 8981 programmable timing computer and pro coil with 8.5 mm wires. The plugs are Autolite racing plugs that are new gapped at .040.

The problem or "noise" I am hearing is a sort of "ping" through the carb not in the combustion chamber. It also has a hesitation and runs rough while making this noise. It only occurs between 2500 and 3500 rpm. The car has a 5500 stall. The car is timed at 28 degrees initial (or idle timing) and 36/38 degrees full advance coming on at around 3500. I run 114 76 Gas. A few people have told me it is cross fire. I have inspected all the plug wires, isolated them, added new boots and new connectors where needed. I have also made sure the pickup harness that runs from the distributor and timing box is away from any other wires. I am at a loss. Does anyone have any ideas?

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Old 08-18-2002, 09:46 AM
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Have you checked the rocker to studgirdle clearance?This may be a MSD problem?This box has the electronic advance? right? try turning the advance down to base timing to test.
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Old 08-18-2002, 09:53 AM
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Roy,

Thanks. Rocker to stud girdle is fine. I had the valve professionally set recently to Lunait spec. My thought is MSD, however I am not aware of a test procedure to find this problem other than sending the box(s) back to MSD.

I am not sure what you refer to "base" timing. The car will not run well below 28 degrees at idle. I have had several people tell me the car shouldn't run below this setting the way the motor was built. I am willing to try anything but I have played with retarding the timing (to run it on pump gas) it just runs like a dog below 28 at idle.
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Old 08-18-2002, 10:50 AM
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Try running it at 28 disconect the timing box or set it down to 28, Have you tryed it with out the Timing computer? Set timing to 36-42 at 3000 rpm just to see if the pinging goes away,This may give u a hot start problem ,You can pump the gas when cranking to get it started, if you have a real starter!
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Old 08-18-2002, 10:55 AM
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Thanks Roy,

Good idea. I haven't tried it without the timing computer yet. I was hoping not to do that....but oh well.

I don't have a "real" starter thats why the 20 degree retard for starting is enabled. I will give it a try.
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