A Technical Question/Pinging-Yes Me the Pic Guy!
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From: Ontario
A Technical Question/Pinging-Yes Me the Pic Guy!
Last weekend I had a nice 60-mile drive with the Wife to a local heritage village to have brunch. On the way back on the highway I thought I should blow out a little carbon to get the car ready for...well more city driving. So I opened up the four-barrel; nice sound! Saw some 170kph (106mph) for a brief period before a PT Cruiser got in the way. These old L-82s do have spunk! And the brakes also. Putting aside the criticism about my irresponsibility on a public highway (which I do not deny), the car pinged badly on acceleration. I am set at 12 degrees BTDC as per specs. Gas was 93 octane. Any thoughts on this? And I will not do it again!
*Edit*-I also have that idle high at stop problem: the idle in hot conditions at a red light will not come down immediately. The suggestion has been to lubricate the distrib weights. That I will do. Is that part of the pinging problem?
[Modified by paul79, 10:16 PM 8/26/2002]
*Edit*-I also have that idle high at stop problem: the idle in hot conditions at a red light will not come down immediately. The suggestion has been to lubricate the distrib weights. That I will do. Is that part of the pinging problem?
[Modified by paul79, 10:16 PM 8/26/2002]
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From: Toronto
Re: A Technical Question/Pinging-Yes Me the Pic Guy! (paul79)
Paul are you sure stock timing is 12? I thought the L48s were 6 BTDC and the L82s were 10 BTDC. Maybe you are a bit to advanced?
Maybe you have some carbon buildup in there? When (if ever) have the heads been off or the engine rebuilt?
Maybe you have some carbon buildup in there? When (if ever) have the heads been off or the engine rebuilt?
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Re: A Technical Question/Pinging-Yes Me the Pic Guy! (paul79)
Sounds like timing is too far advanced to me. Try backing off about 2 degrees and see what happens. You may also want to check both the vacuum advance and the centrifugal advance to see that they are working properly. :)
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From: The Only Corvette in Gila Bend, Az.
St. Jude Donor '09
Re: A Technical Question/Pinging-Yes Me the Pic Guy! (Big Fish)
Do you have the MTBE in you gas up there?
If you do then that is your problem. It sure kills our performance here in Arizona :mad :mad :mad
I have to run my big block pickup on premium to get it to not knock :cry
If you do then that is your problem. It sure kills our performance here in Arizona :mad :mad :mad
I have to run my big block pickup on premium to get it to not knock :cry
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From: Ontario
Re: A Technical Question/Pinging-Yes Me the Pic Guy! (Desertdawg)
MTBE has caused many problems here in Canada. Shell has settled quietly out-of-court with many new car owners who have had emissions problems. I do not recall the details. I tend to use Sunoco 94 octane with 10 ethanol. But the last two fill-ups I used another brand. I will switch back to Sunoco and see what happens.
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From: Canada
Re: A Technical Question/Pinging-Yes Me the Pic Guy! (paul79)
I find that the engine runs best with Sunoco, either 92 or 94, using Esso it just doesn't sound right, and Shell is in between the other 2. I made the mistake of buying Pioneer last weekend and the engine sounded like I needed to tighten valves. It seems that there are fewer and fewer Sunoco's around now.
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St. Jude Donor '11, '16-'17
Re: A Technical Question/Pinging-Yes Me the Pic Guy! (paul79)
If your mechanical advance isn't returning freely, you're going to have to remove your distributer, disassemble it, and lube the shaft. Make sure you put your distributer gear back on in the same orientation, or your timing will be off. Don't ask me how I know :rolleyes:
:cheers:
:cheers:
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From: The Only Corvette in Gila Bend, Az.
St. Jude Donor '09
Re: A Technical Question/Pinging-Yes Me the Pic Guy! (paul79)
I hate the MTBE crap.
It stinks, and it kills the MPG, and power of anything you put it in... :mad
I wish Arizona would get rid of it...
It stinks, and it kills the MPG, and power of anything you put it in... :mad
I wish Arizona would get rid of it...
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From: Ontario
Re: A Technical Question/Pinging-Yes Me the Pic Guy! (The_Dude)
Or I can put Plan B into action. This re-built distrib with Moroso weights and springs has been sitting in the basement for three years. I may give it a try.
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St. Jude Donor '11, '16-'17
Re: A Technical Question/Pinging-Yes Me the Pic Guy! (paul79)
I'm having exactly the same problem with my '76 Cadillac. I did the distributer removal and lubing over the weekend. The problem with this is I think it made things worse because now that the mechanical advance is working properly, I'm getting more advance. The Cadillac doesn't seem to be using ported vacuum for the vacuum advance, so I'm pretty sure that's my problem (when I connect the vacuum advance I get about 10 degrees more advance at an idle, you might check this). I'm trying to dig up a vacuum diagram for the car to make sure things are hooked up properly. Are you using the ported vacuum port on your Quadrajet for your vacuum advance?
I am very interested in how this turns out for you. If I'm able to fix my Cadillac, I'll let you what I ended up doing. For now, I'm just going to retard the timing a couple of degrees at a time until the pinging stops. :cheers:
I am very interested in how this turns out for you. If I'm able to fix my Cadillac, I'll let you what I ended up doing. For now, I'm just going to retard the timing a couple of degrees at a time until the pinging stops. :cheers:
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From: Ontario
Re: A Technical Question/Pinging-Yes Me the Pic Guy! (The_Dude)
Dennis, I will admit my ignorance. I do not know if it is ported or not. I do know it is in the stock place on the Q-Jet!
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St. Jude Donor '11, '16-'17
Re: A Technical Question/Pinging-Yes Me the Pic Guy! (paul79)
That looks like the same place my '80 is hooked too. I think I'm just knowledgable enough to be dangerous. I could take my car to a mechanic, but that would take all the fun out of it. Do you have a mityvac or something similiar, to check your vacuum advance? If it advances with too little vacuum, it could cause this problem. Using your rebuilt distributer would eliminate this possibility.
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From: St. Charles IL
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Re: A Technical Question/Pinging-Yes Me the Pic Guy! (paul79)
Paul, everyone here has had some great suggestions, particularly the one about poor quality gas. The bottom line is if that is the only gas you can get in your area, you will need to tune the timing advance curve so the engine will run as best it can with it. Lars has written a couple of great articles on this subject, including matching the vacuum advance to the operating characteristics of your engine. Check out his articles in the Corvette FAQ site, should give you all the info you need. :seeya