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?

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Robert S.
1986 Dodge D150

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?

Interesting. Very big no-no both Federally and (especially) in California. How are you planning on passing your next smog check...?
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.
…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.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

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.

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Robert S.
1986 Dodge D150

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.
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.

I'll try switching out the distributor and see if that helps

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Robert S.
1986 Dodge D150