Engine pinging
Thread Starter
Melting Slicks
Joined: Jun 2007
Posts: 2,623
Likes: 22
From: Boise Idaho
St. Jude Donor '09-'10, '15, '17
Engine not pinging, then later on the same tank of gas, engine is pinging screams vacuum leak to me. Vacuum systems are tight just before they develop a leak, then you don't get the advance that you need. Yes, it COULD be a number of other things, but a sudden propensity to ping is most likely caused by something in the vacuum system losing its seal.
Testing vacuum now will be helpful, but especially for a non-stock engine, having a baseline would be even more helpful. Failing that, I would go all Eagle Eyes on the vacuum advance hoses to see if something looks dry rotted, loose, or had worked itself off of its connection, and go from there.
Testing vacuum now will be helpful, but especially for a non-stock engine, having a baseline would be even more helpful. Failing that, I would go all Eagle Eyes on the vacuum advance hoses to see if something looks dry rotted, loose, or had worked itself off of its connection, and go from there.
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
It doesn't have a vacuum advance? Please give us a picture of it so we can see what you're dealing with. Pinging would indicate timing too far advanced for the octane of gasoline you're using.
Thread Starter
Melting Slicks
Joined: Jun 2007
Posts: 2,623
Likes: 22
From: Boise Idaho
St. Jude Donor '09-'10, '15, '17
Its an accel tach drive dist.
Blocked off the manifold vacuum port for the lights/wiper door and test drove, but no effect-still pinging.
Last edited by TMU; Aug 29, 2015 at 09:10 PM.
Team Owner
Joined: Jul 2008
Posts: 23,419
Likes: 22
From: In limbo
St. Jude Donor '13-'15, '17 thru '22
I'm not sure what you mean by "electronic dist without vacuum advance". A previous owner replaced my points ignition with electronic ignition, but I still need vacuum advance to run properly. I see you posted a too-close, badly overexposed picture of your distributor. We need better pictures to get an idea of what is going on here.
Instructor
Joined: Jul 2007
Posts: 245
Likes: 2
From: Hope Indiana
Back to the original post. Your distributor could have slipped. Make sure the hold down clamp is tight. Either way, best to start with checking timing like others on the thread have mentioned. Your base timing is probably going to be more advanced than the factory settings, but you can find them here for reference:
http://www.tpocr.com/corvette1.html
Why not just retard your timing by 4 degrees and go out and drive and see if it clears it up?
You should check all of your plugs too. May have a cylinder with oil in it from a leaking valve seal. Is it smoking at idle?
Thread Starter
Melting Slicks
Joined: Jun 2007
Posts: 2,623
Likes: 22
From: Boise Idaho
St. Jude Donor '09-'10, '15, '17
Not all distributors have vac advance. It looks clear from the photo that he doesn't have vac advance. It's not "needed".
Back to the original post. Your distributor could have slipped. Make sure the hold down clamp is tight. Either way, best to start with checking timing like others on the thread have mentioned. Your base timing is probably going to be more advanced than the factory settings, but you can find them here for reference:
http://www.tpocr.com/corvette1.html
Why not just retard your timing by 4 degrees and go out and drive and see if it clears it up?
You should check all of your plugs too. May have a cylinder with oil in it from a leaking valve seal. Is it smoking at idle?
Back to the original post. Your distributor could have slipped. Make sure the hold down clamp is tight. Either way, best to start with checking timing like others on the thread have mentioned. Your base timing is probably going to be more advanced than the factory settings, but you can find them here for reference:
http://www.tpocr.com/corvette1.html
Why not just retard your timing by 4 degrees and go out and drive and see if it clears it up?
You should check all of your plugs too. May have a cylinder with oil in it from a leaking valve seal. Is it smoking at idle?
edit:
Plugs checked and looked good, light Gray and no fouling. Replaced with one step colder plugs, no test drive yet. No smoking at idle.
Last edited by TMU; Aug 31, 2015 at 02:00 AM. Reason: spark plug change
Safety Car
Joined: Jan 2009
Posts: 3,736
Likes: 56
From: anchorage ak
Chexk it to see if it's all good, if so try adding more fuel and check the timing. If it's all good and still pings it might be carbon build up which can be cleaned by running water through the cylinders while running.
Thread Starter
Melting Slicks
Joined: Jun 2007
Posts: 2,623
Likes: 22
From: Boise Idaho
St. Jude Donor '09-'10, '15, '17
So the distributor has no vacuum advance, but it's probably has a mechanical advance, you need to Google the distributor and figure out how to get to the mechanical advance
Chexk it to see if it's all good, if so try adding more fuel and check the timing. If it's all good and still pings it might be carbon build up which can be cleaned by running water through the cylinders while running.
Chexk it to see if it's all good, if so try adding more fuel and check the timing. If it's all good and still pings it might be carbon build up which can be cleaned by running water through the cylinders while running.
In the afternoon I'll see if I can find a number on the distributor, google and see if it has a hidden advance somewhere.
I did add more fuel before last test drive and it continued pinging.
Maybe I'll try the water thing next, not sure just WTH is causing this issue
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Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,399
From: SW Florida.
i have a feeling evereything is computerized with his dist. we have no vac on boat distributors cuz there is no such thing as light load except at idle. dist has about 22 degrees of advance built in and comes in total by 3500 rpm and doesn't care about throttle load. he needs to get a good light and check his total advance curve. he probably doesn't have enough total advance so is running too much initial. vacuum advance is for gas mileage, not performance. OP you need to remove that boat distributor from your car...i could use it on my pantera...
Thread Starter
Melting Slicks
Joined: Jun 2007
Posts: 2,623
Likes: 22
From: Boise Idaho
St. Jude Donor '09-'10, '15, '17
Test drove after new plugs and half a can of carb cleaner down the throat, but there was still pinging. What's strange is that I redlined it once in second and no pinging, but pings in 3rd or 4th starting around 2,500 rpm. Could be from lugging a little then flooring it I suppose.
Found one spark plug wire that had been on the header and a half inch of silicone gone on one side, but no damage to the inner shielding. Rerouted the wire and did not observe any arcing.
Looked at the dist and there is dime size hole that looked like it might have been for a vacuum advance at one time.
Did not have a lot of time to work on the car today.
Found one spark plug wire that had been on the header and a half inch of silicone gone on one side, but no damage to the inner shielding. Rerouted the wire and did not observe any arcing.
Looked at the dist and there is dime size hole that looked like it might have been for a vacuum advance at one time.
Did not have a lot of time to work on the car today.