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1979 454 PINGING under load


toiletjockey's Avatar
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05-30-02, 06:24 PM   #1  
toiletjockey
1979 454 PINGING under load

I have a 1979 Chevy 3/4 ton P/U with a 454. I recently installed a new distributer,cap,plugs and wires. I also rebuilt the carb. I have a fifth wheel camper (loaded) weighs about 8,000#. It doesn't matter if I'm going up or down hill the motor pings. Only loaded. I had timing right on factory specs with new distributer but stopped and retarded timing about 2-3 degrees. This helped and power seemed to pick up but the ping didn't go away. Is it still timing or low octane gas? I have have thought of putting on an open element air cleaner.

 
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05-30-02, 10:06 PM   #2  
rwv77
pinging

id try a higher octane fuel first it my take a couple of tank fulls to work

 
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05-30-02, 10:30 PM   #3  
knuckles
1. Check your EGR system. A malfunctioning EGR system will cause a ping condition.

2. Check your heated air cleaner. Make sure it diverts to fresh air once the engine has warmed up.

3. Check for a lean a/f mixture.

Also, a couple of questions to help us narrow things down:

1. Does it ping at wide open throttle? If so, you can rule out the EGR.

2. Have you checked fuel pump pressure & volume? Checked for a stuck power piston in the carb?(unlikely, but it does happen)

3. How many miles on this engine & what kind of driving do you normally subject it to?

4. Does the engine burn any oil between changes?

 
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05-31-02, 02:34 PM   #4  
toiletjockey
Knuckles..
I have believe it or not only 125,000 on the motor.
It uses 1 quart @ 2,500 miles of a 3,000 mile oil change interval.
(The plugs are always clean though&they never oil foul)
It pings only loaded with the camper and its all the time. Part throttle full throttle up or down hill. I just recently bought the camper and I have used the truck to pull and carry heavy loads before just not this much and it never pinged before. When bringing the camper home the first time I had brought my timing light and stopped and retimed because of the ping. It quieted the ping down some and it seemed to pick up alittle power too.
This is not a daily driver. Not @ $1.45 a gallon HA HA! This truck just gets used as a horse. I honestly shouldn't pick on the gas mileage. I get about 8mpg loaded 10-11mpg empty.
I do not know what the fuel press. is but I did put on a new metal fuel line when I rebuilt the carb. The last owner had it all twisted by the fuel filter. I put alot less bends in it than the factory did. Do you think maybe the fuel pump is getting tired? Do they get changed out like a small block? Thanks for any help!!

 
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06-01-02, 06:23 AM   #5  
Joe_F
Always start with the basics or it will soak you fast for money in a jiffy. Knuckles has you on the right track.

Assume everything's wrong when you buy a used vehicle. You have no idea what to expect, so test things first in order so you can rule them out as the cause of your problems.

 
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06-02-02, 06:33 AM   #6  
Iwould check to see if its running hot while towing.If it has an auto trans add a cooler,drop the thermostat from 180 to 160 and check your thermostatic fan clutch.If the fan clutch is tired at 125k miles you may want too install a centrifugal fan clutch,they improve cooling.Also make sure you have good coolant flow in the radiator.

 
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