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225 Preignition/Pinging Problem
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Author:  smittyp5 [ Tue Mar 31, 2015 10:26 am ]
Post subject:  225 Preignition/Pinging Problem
I have a 1986 ex-US Navy D150 that was equipped with twin cats and the lean burn system. I removed the cats and replaced the muffler with a glasspack. I then replaced the carb with a 1920 Holley and replaced the distributor with a Mopar electronic ignition kit. The original timing on the lean burn was set for 15 degrees BTDC. With the new ignition I started with 2 degrees and the pinging is terrible. I have tried every degree of timing between 15 degrees and TDC, tried disconnecting the vacuum advance and still the same. It also has less power now than with the lean burn. Could anyone point me in the right direction of what to check or do next?
Author:  Reed [ Tue Mar 31, 2015 11:03 am ]
Post subject: 
Have you confirmed that the distributor was not installed with the rotor 180 degrees out? Checked for vibration damper slip? Are you sure it is preignition and not a different noise? Vacuum leak causing lean detonation?
Author:  SlantSixDan [ Tue Mar 31, 2015 11:06 am ]
Post subject:  Re: 225 Preignition/Pinging Problem
Quote:
I have a 1986 ex-US Navy D150 that was equipped with twin cats and the lean burn system. I removed the cats and replaced the muffler with a glasspack
Interesting. Very big no-no both Federally and (especially) in California. How are you planning on passing your next smog check...?
Quote:
I then replaced the carb with a 1920 Holley
This, too, is an automatic smog check failure (wrong carb for the application). Besides that, the 1920 is not necessarily superior to the 1945; in several ways it's actually inferior.
Quote:
and replaced the distributor with a Mopar electronic ignition kit
…If you mean the Mopar Performance kit, this is the source of your poor performance and persistent ping. The Mopar Performance kit comes with a distributor that has only one, extremely low-tension centrifugal advance flyweight spring. It dumps in all the mechanical advance just off idle. This is arguably fine for drag racing (but arguably not); it's definitely the wrong thing for street use. Also, the orange-box ignition module quality has been poor and dropping for years now.

You'd have a better result with the HEI upgrade, but unless you're crafty and clever (hide the HEI module inside the housing of the original spark control computer, such as) you should still expect to flunk smog.
Author:  smittyp5 [ Tue Mar 31, 2015 3:31 pm ]
Post subject: 
I'm not worried about the smog...I am registered in an area that doesn't require a smog check. I did verify that the distributor is in correctly. I will check to make sure the dampener didn't slip. The kit that I bought from ebay is the one sold by moparpartsus which comes with the black box, distributor, harness and ballast resistor. If in fact this is the Mopar performance unit you were speaking of, what can i do to it to remedy the situation? Also, it is definitely pinging. It mostly goes away at wide open throttle but anything less, it pings. It's especially bad accelerating upgrade on curvy mountain roads. It's also very bad after it has been freeway running and you accelerate after the first stop.
Author:  Reed [ Tue Mar 31, 2015 5:25 pm ]
Post subject: 
Quote:
I'm not worried about the smog...I am registered in an area that doesn't require a smog check.
Actually, technically, you aren't. Under Federal law, it is unlawful to remove or modify ANY part ofANY emissions equipment on your vehicle. State emissions laws will vary, and you may live in an area where the STATE doesn't care what you do, but you are still violating FEDERAL law. Granted, the chances of getting caught are slim, but there.
Quote:
I did verify that the distributor is in correctly. I will check to make sure the dampener didn't slip. The kit that I bought from ebay is the one sold by moparpartsus which comes with the black box, distributor, harness and ballast resistor. If in fact this is the Mopar performance unit you were speaking of, what can i do to it to remedy the situation? Also, it is definitely pinging. It mostly goes away at wide open throttle but anything less, it pings. It's especially bad accelerating upgrade on curvy mountain roads. It's also very bad after it has been freeway running and you accelerate after the first stop.
Sounds like too much vacuum advance and too light of a spring(s) in the distributor. The fast and easier way to solve the problem is to get a distributor out of a mid 70s era Dodge truck with a slant to replace your current distributor. The harder way is to fine tune the distributor advance curve in your current distributor by swapping out advance springs and playing with the vacuum advance.
Author:  smittyp5 [ Tue Mar 31, 2015 6:04 pm ]
Post subject: 
I'll try switching out the distributor and see if that helps
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