I have a 383 with 9 1/2 compression, alum heads, moderate cam. Nothing special. 440 HP. It ran great for 2 years. Engine is 5 years old. 3 years ago, the transmission was replaced and after that the pinging started. It was HORRIBLE at anything over 3000 RPM!! I replaced the plugs with the same (Autolite AR3933). It got much better. It started pinging at 4 grand after that. I tried hotter plugs, colder plugs, different brands, different gaps, different wires, etc. It has not been right since. I have changed the plugs, wires, distributor cap, rotor, coil, etc. The AF ratio is great according to a dyno tune. Even the shop couldn't figure out why is was pinging. The timing is only at 11 degrees initial. When new, it was at 14. The timing curve seems correct. All in is only 32 degress or so. I use 93 octane from different stations to be sure it isn't bad gas. It lately has started to "break up" and run like crap at less than 4000 RPM. Is it possible that the MSD distributor is bad or damaged from the tranny swap? It has a Holley 770 Avenger. Is the carb notorious for issues? Was there a wire pinched when the tranny was replaced? I have tried everything I can think of. I am likely going to ship it to an expert soemwhere. I will NOT go back to the builder of the engine because I had a HORRIBLE experience here in VA. I have a video of its terrible performance. I will post a YouTube link soon. Any ideas???
Pinging *** help!!!!
Deangelo66
I have a 383 with 9 1/2 compression, alum heads, moderate cam. Nothing special. 440 HP. It ran great for 2 years. Engine is 5 years old. 3 years ago, the transmission was replaced and after that the pinging started. It was HORRIBLE at anything over 3000 RPM!! I replaced the plugs with the same (Autolite AR3933). It got much better. It started pinging at 4 grand after that. I tried hotter plugs, colder plugs, different brands, different gaps, different wires, etc. It has not been right since. I have changed the plugs, wires, distributor cap, rotor, coil, etc. The AF ratio is great according to a dyno tune. Even the shop couldn't figure out why is was pinging. The timing is only at 11 degrees initial. When new, it was at 14. The timing curve seems correct. All in is only 32 degress or so. I use 93 octane from different stations to be sure it isn't bad gas. It lately has started to "break up" and run like crap at less than 4000 RPM. Is it possible that the MSD distributor is bad or damaged from the tranny swap? It has a Holley 770 Avenger. Is the carb notorious for issues? Was there a wire pinched when the tranny was replaced? I have tried everything I can think of. I am likely going to ship it to an expert soemwhere. I will NOT go back to the builder of the engine because I had a HORRIBLE experience here in VA. I have a video of its terrible performance. I will post a YouTube link soon. Any ideas???21 - 40 of 117 Posts
Joined
·
6,338 Posts
I can't tell from your video so this may sound crazy...Are you sure it's "pinging"(detonation) and not a header leak or arcing plug wire. If there is any doubt you could induce pinging(it won't kill it!) for comparison.
Joined
·
531 Posts
Nope. Not a crazy question. I think that if it were a header leak, I would hear it at all RPM's. it would just get louder. A few other folks, including a mechanic, felt it was a "pinging". In the attached video, it is pinging AND "breaking up". It actually got worse with new plugs. Before I changed the plugs, it was just pinging. I replaced the plugs with the exact same brand and part number (Autloite AR3933). Immediatley afterwards, it got worse for some reason. I looked at the car in teh dark. No arcing was evident from the wires nor plugs. I actually bought some Chamion plugs just to try one more plug change for comparsion as I threw the old Autolites away without thinking. I should have put those back in. What is the likelihood of having a bad bacth of Autolites?? Probably remote. Thanks for all the suggestions and help. I am at my wit's end. I mayhave to send the car off to an expert as crazy as that sounds for a naturally aspirated Gen 1 block. It should be a simple fix on such a simple motor.
BTW Beth is correct - you should be running both vacuum and mechanical advance on most street motors. Not sure if this will help this particular problem but your motor will perform better. The link in the second post of this thread is a great article that explains why: http://www.camaros.net/forums/showthread.php?t=191842&highlight=vacuum+advance
I've been reading DeAnglo's thread on the side for anything I may have missed when I looked at it last year. Let me add the symptoms I had found,
Not a symptom, but, a beautiful burgundy '67 with a black deluxe interior, chrome appearance pkg, console with gauges.
The harmonic balancer is labeled correctly, ie, zero is zero degrees.
Measured 14° BTDC initial timing, reset the mixture and gained 1.5 inches of vacuum, read then, 15 inches.
Engine has a 160°F thermostat and a young alum radiator.
Cylinder compression is about 175 PSI., checked two, I believe, memory eludes at the moment, maybe DeAnglo remembers.
Went for a ride, I listened, yes pinging, just like in an '80's vehicle.
Traveling at any rpm, 2000tro 4000 rpm and nail it, pings.
If slowly depress the pedal, no ping.
Returned to the driveway, took out both vacuum adv by plugging the hose, and installed heavy centrifugal springs.
The above step took the total timing from 36° at 3000 to 20° at 4000.
Rode again, still pinged.
Put everything back the way it was and the same results, one ride is a carbon copy of the other ride.
I suspect either the wrong head gaskets used as in too much quench, camshaft advanced too much, or maybe a bad batch of Autolites.
Not a symptom, but, a beautiful burgundy '67 with a black deluxe interior, chrome appearance pkg, console with gauges.
The harmonic balancer is labeled correctly, ie, zero is zero degrees.
Measured 14° BTDC initial timing, reset the mixture and gained 1.5 inches of vacuum, read then, 15 inches.
Engine has a 160°F thermostat and a young alum radiator.
Cylinder compression is about 175 PSI., checked two, I believe, memory eludes at the moment, maybe DeAnglo remembers.
Went for a ride, I listened, yes pinging, just like in an '80's vehicle.
Traveling at any rpm, 2000tro 4000 rpm and nail it, pings.
If slowly depress the pedal, no ping.
Returned to the driveway, took out both vacuum adv by plugging the hose, and installed heavy centrifugal springs.
The above step took the total timing from 36° at 3000 to 20° at 4000.
Rode again, still pinged.
Put everything back the way it was and the same results, one ride is a carbon copy of the other ride.
I suspect either the wrong head gaskets used as in too much quench, camshaft advanced too much, or maybe a bad batch of Autolites.
Joined
·
531 Posts
Thanks, Everette!!! You nailed it!!! Weird that this happened after 2 years of PERFECT running. Now it has been 3 years of aggravation.
And yes, I think the pressure was 175 psi.
I am going to install a set of Champion plugs this weekend for the heck of it. ya never know. The wires are Taylor, 8 mm. They were replaced 2 years ago and only have a 1000 miles on them max. I only put 100 miles at most on the car per month during great weather. I wonder if my MSD distributor has a bad internal part. Thanks again!
And yes, I think the pressure was 175 psi.
I am going to install a set of Champion plugs this weekend for the heck of it. ya never know. The wires are Taylor, 8 mm. They were replaced 2 years ago and only have a 1000 miles on them max. I only put 100 miles at most on the car per month during great weather. I wonder if my MSD distributor has a bad internal part. Thanks again!
I know some may question this, but have you run any really good carb/injector cleaner? I like you don't drive my camaro more than 1000-1200 miles in a season and carbon buildup on the edges of the piston/combustion chambers can cause detonation due hot spots created by the carbon buildup. I had an issue like what you are discribing years ago on a different car, ran some strong fuel cleaner in a couple of tanks of fuel back to back to clear the carbon and the problem was solved. I now run cleaner in all my vehicles from time to time to keep things clean. If you haven't tried this, what's the harm in trying something you haven't tried yet. Good luck and I hope you can find the problem without having to send the car out for diagnostics.
Joined
·
3,193 Posts
Here's a good way to check for a vacuum leak:
Get a small propane bottle and install a heating tip. With the engine idling, crack open the propane bottle (don't light it !) and move it around the base of the carb and where the intake meets the cylinder heads.
If the idle speeds up, you've found a leak.
Get a small propane bottle and install a heating tip. With the engine idling, crack open the propane bottle (don't light it !) and move it around the base of the carb and where the intake meets the cylinder heads.
If the idle speeds up, you've found a leak.
Had not thought of carb cleaner to the gas tank since I have not seen Wynn's Carburetor Cleaner on the shelves since early '90's, and yes, it did work. Certainly could be carbon buildup or a protuding piece in the combustion chamber glowing red hot during the compression stroke starting as compression heats up anything.
Reduced timing lowers the combustion pressure by delaying the point of ignition creating less heat reducing pinging, the collision of two flame fronts in the combustion chamber. One front started by the spark plug, the other front started by a super-heated protrusion, or heated carbon deposits, in the chamber.
Remember, at cruise, engine is creating a vacuum, less air pressure in the combustion chamber than at WOT, atmospheric pressure (no vacuum), more air pressure. More air pressure, higher combustion pressure.
Reduced timing lowers the combustion pressure by delaying the point of ignition creating less heat reducing pinging, the collision of two flame fronts in the combustion chamber. One front started by the spark plug, the other front started by a super-heated protrusion, or heated carbon deposits, in the chamber.
Remember, at cruise, engine is creating a vacuum, less air pressure in the combustion chamber than at WOT, atmospheric pressure (no vacuum), more air pressure. More air pressure, higher combustion pressure.
I would be very suspect of the distributor, I am on my third 8360 from MSD, I had one that acted like a rev limiter at 3000 rpm when driving, rev it up in the garage with a timing light on it and it sounded fine but as soon as you put a load on the engine it would fall apart.
Dan E.
69 SS396 4spd. 4.10 posi. x66 coupe
Dan E.
69 SS396 4spd. 4.10 posi. x66 coupe
Crap. I was planning on getting one of those soon.
Joined
·
531 Posts
Like Everette said.
Less timing should cause less pinging. The AFR averaged 12.8. And it only pings at WOT.
Chet, I actually used a can of Seafoam to make sure that it wasn't carbon buildup. That's supposed to work on that. I will still try a can of carb cleaner. You never know! Thanks!
That is a great idea. Is is possible to have a leak occur when those parts have never been off?
Thanks, Everette.
Thought I would give my two cent worth, I have been mechanicing many years and helt ASE masters certificate. I have 69 Camaro with 400 SB .030 over that I thought had a pinging, high timing, exhaust leak, and check many things, still had good power but had spark knock sound under acceration . Turns out had blowed head gasket between 3 & 5 cylinders, so check compression or cylinder leakage test.
I tried a points dizzy. in my car and that solved my problem, so I emailed MSD explaining my problem, they had me send the dist. back and they seny me a new one. I set up the curve on that one and it has been fine, but I still carry the points dist. with me in the trunk. I modified the wiring a little in order to run either dist. . I think the points dist. was $63.00 at napa.
Dan E.
69 SS396 4spd. 4.10 posi. x66 coupe
Dan E.
69 SS396 4spd. 4.10 posi. x66 coupe
Joined
·
531 Posts
I will def keep that in mind! the last mechanic said that I had great compression. he even said it may be a little high. The engine is 9 1/2 to 1. I even tried 100 octane and it still did it.
Ave Thats not a good 'reading' its important to work with the range
How lean does it get?
And having a spare dizzy...complete wit HT leads is a good idea....I still have my orginal points BUT be careful, over the yrs those pionts detriate....I now have a spare HEI...bushes a little worn now, but I know it has the right curve and it works....great for a spare if I think something is wrong in the dizzy...or If need a new dizzy get to use in the mean time.
That is a very likely issue...It could be so small a compression will never pick up....check the spark plug is not signigicantlu cleaner than the rest....even better quicker than a leakdown/compression is a HC test on the radiator.
Joined
·
531 Posts
I don't know the exact AFR at a given RPM. I was just told by the shop that it was great.
My next step is to swap the distributor with a friend. He has an HEI.
An HC test checks for oil in the coolant, correct? I really hope it's not a head gasket.
I just finished changing the plugs to Champion equivalents. No change. The old plugs looked fine to me. They only had 10 miles on them though. I wanted to try a different plug in case they were defective. Doing the exact same thing. Sputtering, pinging and acting weird. This sucks...
I even removed the boot protectors just in case they were causing it to arc. I was thinking about getting new wires, but these Taylor wires are only 2 years old and have less than a few hundred miles on them. Maybe they broke down. I did have a bad coil wire. The electrode was broken in half and the car was backfiring and cutting off. Maybe that whole process put a load on those wires. I am grasping at straws. I am open to any and all suggestions.
My next step is to swap the distributor with a friend. He has an HEI.
An HC test checks for oil in the coolant, correct? I really hope it's not a head gasket.
I just finished changing the plugs to Champion equivalents. No change. The old plugs looked fine to me. They only had 10 miles on them though. I wanted to try a different plug in case they were defective. Doing the exact same thing. Sputtering, pinging and acting weird. This sucks...
I even removed the boot protectors just in case they were causing it to arc. I was thinking about getting new wires, but these Taylor wires are only 2 years old and have less than a few hundred miles on them. Maybe they broke down. I did have a bad coil wire. The electrode was broken in half and the car was backfiring and cutting off. Maybe that whole process put a load on those wires. I am grasping at straws. I am open to any and all suggestions.
21 - 40 of 117 Posts
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
