OK, IT STARTED ABOUT A MONTH AGO, IT WAS ACTUALLY A COUPLE OF ISSUES, THE FIRST WAS PINGING UNDER LOAD, THE SECOND WAS A BOG WHEN YOU NAILED THE GAS AND FORCED THE DOWNSHIFT(AUTOMATIC BY THE WAY). ANYHOW REBUILDING THE CARB FIXED THE WOT BOG, BUT I STILL HAVE PINGING WHEN THE CAR IS UNDER LOAD, JUST SHY OF FORCING A DOWNSHIFT IN DRIVE. TIMING IS SET AT 4 DEGREES,(I USED TO BE ABLE TO RUN IT AT 6, ITS THE 300HP ENGINE AND I HAVE NEVER BEEN ABLE TO RUN ANY HIGHER THAN 6 INITIAL). I HAVE EVEN SWAPPED DISTRIBUTORS AND THE PROBLEM PERSISTS(BOTH ARE DUAL POINT MECHANICAL ADVANCE ONLY). I HAVE ALREADY CHASED VACCUUM LEAKS, AND CANT FIND ANY, THAT WOULD CAUSE A LEAN CONDITION. I'VE ALSO TRIED ADDING OCTANE BOOST, IDLES BETTER BUT STILL PINGS. THE MOTOR IS HIGH MILEAGE(ORIGINAL), SOMWHERE AROUND 180k, I'M TRYING TO BUY SOME TIME BEFORE I SWAP DRIVETRAINS IN THE SPRING. ANY HELP WOULD BE APPRECIATED, I'M RUNNING OUT OF IDEAS.

 

You might have carbon build up which may be causing the ping. Have you tried the GM upper eng cleaner, NAPA sea foam or the 'water' cleaning method? It might do the trick.

 

I was having this problem with my '76 Cadillac, but only after the car fully warmed up. How's your thermostat?

 

160 hi flow stat, new griffin aluminum radiator, temp seems good, right at 160

 

i'll call napa and see if they have sea foam. works well does it.

 

Try this link:

http://65.113.119.28:7001/zerothread?id=362439 .

It is loading very SLOW so not sure if the link is working. Try doing a search on 'water' in the c3 section and there is a few threads cleaning carbon deposits with various products and water.

****THAT LINK IS NOT WORKING EVEN FROM THE SEARCH PAGE******


[Modified by Fevre, 1:21 PM 12/11/2002]

 

THANKS, I GUESS I'LL TRY WATER FIRST, ALREADY HAVE LOTS OF THAT. I DONT HAVE A NAPA LOCAL TO ME HERE. I'LL POST TOMORROW ON THE OUTCOME...

 

Other guys here sweat by dribbling auto tranny fluid into the carb (smokehouse69 is an advocate of this method). Personally, I feel more comfortable putting a burnable petroleum product down the carb than H20, though I understand it does make a helluva cloud of smoke. You've probably already tried higher octane, but if all else fails, get some blue av gas from your local communter airport and mix that in at 30-50% & see if that does de-ping her. Also, have you checked your total timing? There's a little plastic restrictor on the distributor that limits the total advance, and if that's gone missing you could be getting too much advance.

JB

 

I have same pinging under load condition with distributor perfectly curved and new vac advance. A possible diagnosis for mine was a rich condition created by small primary rods since my WOT is Ok. Just my .02

 

maybe i'll try the ATF, now that you mention it way back when, I remember reading that in "how to keep your volkswagen alive for the complete idiot" already running octane boost, whatever it is its something new. she always ran good on 91, and ran a little better with octane boost. my total advance is low, i think it was around 26. with the stock cam(300hp) I've never been able to run alot of advance without pinging and dieseling. that's why the motor on the stand is getting the 350-350hp cam instead, but i wont have the finances till spring for the heart transplant. i'm hoping that one of these tricks will work, cause with my luck i will get this motor running right again just in time to pull it!

 

Other than carbon which is probably only part of it. Try a colder plug if your plugs look near white carbon deposits on the tip. Your big thing in a high mileage stock motor is cam chain and gear failure. To test how bad your chain/gear are (This causes late cam timing and detonation) Pull the dist cap and grab the rotor. on a tight motor you should only be able to turn it back and forth a little bit. that's the slop in the dist gear and cam gear messing.

If you can move the thing 20-30+ degrees your cam chain is so stretched that your cam timing is causing cylinder pressure issues. The sorry nylon gear can even break so the cam has skipped timing and your all out of whack.

Another possibility is and it happened to my L-82 is the damper broke from the inner to the outer ring so your not really reading the true timing because my mark had changed. I thought that I had major motor problems and all it was was a new Damper.

 

i'm still searching for the answer...tried water in the carb last night, didnt see much smoke so tried ATF after(lots of smoke), ended up running a half quart of each through the carb. i'll drive her tonight to see if that did anything. I hadnt thought of the balancer slipping, I will have to check that, i guess i'll just retard the distributor till it quits pinging and see if she will still get out of her own way, if she does i'll know that it has slipped, if she doesnt i'll have to assume it didnt. i know that when i swapped distributors that i brought the timing mark to 0 and the rotor was pretty close to #1 though. i learned about the nylon gear when i got the car a little over 2 years ago. teeth were missing(laying in the oil pan). i swapped to a Cloyes double roller, so the chain should be tight. I had already swapped to one heat range colder, running a R43 instead of the R44. i guess if i cant get it figured out this weekend I will just park her and start collecting parts to put the replacment motor together with. i hate to sink any more money in to the current one, since i have a replacment sitting on an engine stand. thanks for the input, i'm at the point of frustration, last night when i drove home from work, i couldnt step on the gas at all without pinging:mad . Almost makes me wish i had a louder stereo so i wouldnt hear the popcorn machine under the hood!!

 

Sorry about your pinging issues. When I bought my 1972, the previous owner had a 406 SB with 64cc heads and flat-top pistons. He wired the mechanical advance mechanism closed to prevent pining, but with the help of forum members, I replaced the heads to proper 400SB and my pinging issues went away.