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I have a low mileage STOCK 428 Pontiac in a 69 Bonneville,, It is rated at 10.75 / 1 compression,, so I have lots of trouble with pinging,, even with the highest octane gas I can find and with octane boost additive, I have tried adjusting the timing, but that doesn't seem to help much,, anyone have any ideas ?? would a hotter ignition help, like maybe a MSD,?? I don't really want to rebuild the motor , but if I don't do something to cure the problem,, I won't have any other choice,, Any ideas would be appreciated,,, thanks Bill
 

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Grumpy Old Goat Herder
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There are several things for you to try that may help. First, the MSD ignition is a good way to go. You can slow the advance curve down and even bumping up the initial a very little could help if the curve is slowed down. My son suggested that, if your engine has the usual carbon build up, you can break it up and blow it out by running the engine at 2000 to 2500 and "dribbling" water into the carb. He also suggested richening the primaries of the carb. Hope this helps!

Another Bill
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Another idea to consider is some form of water or water/alcohol injection.Jegs sells a kit made by Snow performance,looks like a well thought out kit.This would allow you to keep your high compression and keep the timing advanced for good performance.
 

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I spent a while experimenting with high compression (over 12:1) and propane about 15 years ago and one thing I learned is that for any given heat range an ngk plug will be more prone to pre ignition than a Bosch or Champion.
A 69 Bonne with 10.75:1 will also be more likely to ping than a RA 111 T/A or GTO purely by virtue of the cam profile. Run more overlap and it 'bleeds' off a litle cylinder pressure down low, hell you can retard the stock cam a few degrees to achieve the same end but it will cost you low end torque.
 

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... & Insanity Ensues .....
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water is a very good way to break up the carbon deposits. hold the engine at about a 1/3 throttle and slowly pour it in, pour it only about as fast as you drink a glass of milk

a heavily carboned 4 cylinder motor can take 6 litres or water before its cleaned out, i know because ive done it before on a fiero. - i would drive it till it would hardly even run, and then take 15 minures to clear it out w/ the water treatment :)

youll notice that the thin water vapor out the exhaust quickly turns to a massive smoke screen. this is exactly what you want to see. continue slowly pouring water until the massive smoke screen clears. the exhaust will turn back to being just a thin fog when the engine is fully cleaned out

the exhaust "fog" at teh begining and end of the procedure will look like the fog you get on a cold morning when you start the car. the fog in the middle will make you think your pouring OIL into your engine, lol

after its all cleared out, take the above advise

redo your distributor

if the problem returns, pick up a water injection kit and install it, its much cheaper then having the engine rebuilt w/ lower compression, and isnt harmfull at all
 

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Discussion Starter #8
Thanks guys,,, I have done the water treatment on other engines before, but not sure I jhave done this one,, I didn't drive the car much in the past couple of years, but plan on driving it alot now if I can get it to run with out pinging Thanks again ,, Bill
 
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