Pinging Engine on Acceleration
Thread Starter
Melting Slicks
Joined: Jan 2003
Posts: 2,713
Likes: 31
From: Shreveport LA
LA Events Coordinator
Pinging Engine on Acceleration
Whenever the car reaches operating temp (and the car has been driven for a while) I notice the engine begins pinging on acceleration 
. I have checked the timing (6*BTDC...per repair manual), I run Premium gas all the time and the engine purrs perfectly in Park (700rpm) and Drive (600rpm). I do have a semi-mild cam....SpeedPro 290. Any help would be appreciate.
. I have checked the timing (6*BTDC...per repair manual), I run Premium gas all the time and the engine purrs perfectly in Park (700rpm) and Drive (600rpm). I do have a semi-mild cam....SpeedPro 290. Any help would be appreciate.
Drifting
Joined: Sep 2004
Posts: 1,959
Likes: 1
From: North Bend Ohio
Possible causes:
Spark plug heat range too high
Engine leaning out on acceleration (could be several reasons for this, accelerator pump, power piston spring too soft, primary metering rods too big)
centrifugal advance malfunction (advancing too fast, broken or missing spring)
Carbon buildup in cylinders
Overheated exhaust valve heads
Oil burning in cylinders (oil lowers the octane rating of gasoline)
If this were my car I would pop the distributer cap off just to make sure the advance weight springs are there. Then go two or three steps cooler on plugs. Also make sure you have the proper style plugs. Some of those long reach plugs can put exposed threads in the combustion chamber where they can glow red hot and cause pre ignition. If problem persists map the timing advance curve. Maybe slow it down a little.
Now, if need be, you can start on the carburetor. Richen up the idle mixture. Maybe one step smaller primary metering rod and/or one step stronger power piston spring. There are several other things you could try but they are rather technical and should be saved for if they are really needed or not.
By the way, are you sure the cam was installed correctly? A severely advanced cam could be causing some overly high dynamic compression ratios.
BigBlockk
Later.....
Spark plug heat range too high
Engine leaning out on acceleration (could be several reasons for this, accelerator pump, power piston spring too soft, primary metering rods too big)
centrifugal advance malfunction (advancing too fast, broken or missing spring)
Carbon buildup in cylinders
Overheated exhaust valve heads
Oil burning in cylinders (oil lowers the octane rating of gasoline)
If this were my car I would pop the distributer cap off just to make sure the advance weight springs are there. Then go two or three steps cooler on plugs. Also make sure you have the proper style plugs. Some of those long reach plugs can put exposed threads in the combustion chamber where they can glow red hot and cause pre ignition. If problem persists map the timing advance curve. Maybe slow it down a little.
Now, if need be, you can start on the carburetor. Richen up the idle mixture. Maybe one step smaller primary metering rod and/or one step stronger power piston spring. There are several other things you could try but they are rather technical and should be saved for if they are really needed or not.
By the way, are you sure the cam was installed correctly? A severely advanced cam could be causing some overly high dynamic compression ratios.
BigBlockk
Later.....
Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
Trying pulling your vac adv line and plugging the port on the carb to see if that gets rid of it. If so it may be the can is not functioning properly as mentioned above or the can is pulling too much adv and you need a can that pulls less or give is back faster. check out Lars tech paper on it:
https://www.corvetteforum.com/techti...=115&TopicID=3
https://www.corvetteforum.com/techti...=115&TopicID=3
Melting Slicks
Joined: Aug 2003
Posts: 2,135
Likes: 2
From: Dayton Oh
Another thing to check is the advance springs. Might be broken or too light. Also do a search on Lars timing tips. If you follow his recommendation for properly timing the engine, I bet you quickly see where your problem is.
Pro
Joined: Jan 2004
Posts: 535
Likes: 1
From: Darwin, Australia NT
All of the above plus
Get intake temperatures down. Cool air induction pickup, block heat riser in intake manifold, carb insulator, oil splash shield under intake, insulate exhaust. I even insulate the bottom of the intake and try to get engine operating temperature down with high flow water pump & thermostat and overdrive pulleys.
Vacume advance canister that is adjustable in amount and rate of advance might just do it alone, but all the others will help and make more power.
Vacume advance canister that is adjustable in amount and rate of advance might just do it alone, but all the others will help and make more power.
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Verdad Gallardo
Racer
Joined: May 2000
Posts: 386
Likes: 0
From: Niedernhausen, Germany
Pinging
Another reason might be a slipping outer ring at the harmonic ballancer. Thus the TDC mark is off and any adjustments are wrong. Check the position with a piston stop (instead of spark plug) on #1 cylinder and then turn the engine clock- and counter-clock wise against the stop. Mark both positions on the ballancer. True TDC is right in between the markings.
Regards,
Thomas
Regards,
Thomas