Jim S Posted April 28, 2021 Report Share Posted April 28, 2021 On the 87 Avanti, what should the timing mark be set at? On most of the GM forums people say between 6-8 degrees BTDC. What is recommended for the Avanti 305? Link to comment Share on other sites More sharing options...
IndyJimW Posted April 28, 2021 Report Share Posted April 28, 2021 Get engine to operating temperature. Disconnect single wire connector in engine harness between distributor and ECM. Setting should be on Emission sticker, or set to 6*. Reconnect wire connector. Good luck, Jim Wood Link to comment Share on other sites More sharing options...
Jim S Posted April 28, 2021 Author Report Share Posted April 28, 2021 Most of the smog stuff has been disconnected. Still proceed as you said? Link to comment Share on other sites More sharing options...
IndyJimW Posted April 29, 2021 Report Share Posted April 29, 2021 Yes. The ECM will not hold base time unless you disconnect the distributor to ECM wire. I'll check tomorrow on the wire colors, but it will be a single wire with a connector. Good luck, Jim Wood Link to comment Share on other sites More sharing options...
Jim S Posted April 29, 2021 Author Report Share Posted April 29, 2021 There are two connectors on the distributer. One has two wires and the other has several. Link to comment Share on other sites More sharing options...
IndyJimW Posted April 29, 2021 Report Share Posted April 29, 2021 This is a single wire NEAR the distributor, should be tan on one side of the connector and tan\black on other side. You can also go to www.montecarloSS.com and search their site for info. Their site is full of good info for your Avanti. Good luck, Jim Wood Link to comment Share on other sites More sharing options...
Jim S Posted April 29, 2021 Author Report Share Posted April 29, 2021 Thank-you Jim Link to comment Share on other sites More sharing options...
Jim S Posted April 29, 2021 Author Report Share Posted April 29, 2021 11 hours ago, IndyJimW said: This is a single wire NEAR the distributor, should be tan on one side of the connector and tan\black on other side. You can also go to www.montecarloSS.com and search their site for info. Their site is full of good info for your Avanti. Good luck, Jim Wood I looked everywhere, and cannot find any wires as you described on my car. Link to comment Share on other sites More sharing options...
IndyJimW Posted April 30, 2021 Report Share Posted April 30, 2021 May be located under the passenger dash near the ECM. Not sure where Avanti hid it, but its there. Should be 1 of the wires coming off of the distributor, follow the tan wire. Good luck, Jim Wood Link to comment Share on other sites More sharing options...
Jim S Posted April 30, 2021 Author Report Share Posted April 30, 2021 (edited) What's going on with my engine is hard starts sometimes. And when you shut it down, sometimes it will diesel and knock for a few seconds before it stops running. I was told that the timing was off and setting it properly should correct it. Edited April 30, 2021 by Jim S Link to comment Share on other sites More sharing options...
64studeavanti Posted May 1, 2021 Report Share Posted May 1, 2021 (edited) Sometimes dieseling can be caused by the throttle plates not closing all the way. Could be cause of hard starting as well. Edited May 1, 2021 by 64studeavanti Link to comment Share on other sites More sharing options...
Jim S Posted May 1, 2021 Author Report Share Posted May 1, 2021 1 hour ago, 64studeavanti said: Sometimes dieseling can be caused by the throttle plates not closing all the way. Could be cause of hard starting as well. There was a new carburetor installed by the previous owner just before I got the car. I'll look at that. Thanks. Link to comment Share on other sites More sharing options...
IndyJimW Posted May 1, 2021 Report Share Posted May 1, 2021 15 hours ago, Jim S said: What's going on with my engine is hard starts sometimes. And when you shut it down, sometimes it will diesel and knock for a few seconds before it stops running. I was told that the timing was off and setting it properly should correct it. 13 hours ago, Jim S said: There was a new carburetor installed by the previous owner just before I got the car. I'll look at that. Thanks. Set the timing. Is the carburetor a Quadrajet E4M or an aftermarket. There should be a solenoid that controls plate closing during shutdown. This helps prevent dieseling. Dieseling and knock can also be caused in the Chevy small block by heated deposits. Go to a GM dealers part counter and get a bottle of ACDelco 10-3015 Top Engine Cleaner and follow the directions. You SLOWLY pour it into the carburetor with the engine running, before this came out we would use water at the dealers I worked. Good luck, Jim Wood Link to comment Share on other sites More sharing options...
Jim S Posted May 1, 2021 Author Report Share Posted May 1, 2021 (edited) Yes it is a Quadrajet. Thanks for the info. I looked at the carb and besides the choke coil heater there is only a fast idle solenoid on the opposite side. I took the connector off because it was idling very high when in gear and I could barely stop the car when driving! This car is a real mess! Edited May 1, 2021 by Jim S Link to comment Share on other sites More sharing options...
Jim S Posted May 4, 2021 Author Report Share Posted May 4, 2021 On 4/29/2021 at 8:36 PM, IndyJimW said: May be located under the passenger dash near the ECM. Not sure where Avanti hid it, but its there. Should be 1 of the wires coming off of the distributor, follow the tan wire. Good luck, Jim Wood I can not find any single wires with a connector in this car. (At least that's accessible) Here are photos of the distributer connector and the ECM connectors. The ECM connectors each have a tan wire with a black tracer. I don't know which one to disconnect. I'll have to cut the right one and reconnect. Link to comment Share on other sites More sharing options...
IndyJimW Posted May 4, 2021 Report Share Posted May 4, 2021 I would unplug the distributor connector and remove the wiring from the harness back about two feet, the OEM connector should be there. Or cut the tan wire a couple inches from the distributor, set the timing and reconnect the wire. From what I have been told you can also hook up a scanner and with the engine running it will make the ECM go into base mode. I have never done this and don't know if it works. Good luck, Jim Wood Link to comment Share on other sites More sharing options...
Jim S Posted May 4, 2021 Author Report Share Posted May 4, 2021 Copy. Thank-you Link to comment Share on other sites More sharing options...
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