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RIP, Lead Technician
Category: Chevy
Satisfied Customers: 5591
Experience:  A.S.E Certified Master Technician, AC Delco service training, Ca State Smog License, L1 level
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How to set timing on a Chevy 305?

Customer Question

How to set timing on my Chevy 305 car?

Submitted: 9 years ago.
Category: Chevy
Expert:  RIP replied 9 years ago.

-What year is your Chevy?
-What model is your Chevy?
-How many miles are on your Chevy?
-What type of engine is in your Chevy?
-What have you already tried?

Customer: replied 9 years ago.

1985 but after market motor

g3 van in a motor home



I have already tried to set timing by standred means

Recently had a tune up dne to our 85 chevy 305 had great compression and power prior to tune up, and some hole repaired between manifold and pipe, now no power or compression acts like bad timing, but when you turn the distributor gets worse instead of better. we are fund raaisers and the motor is in our motor home which is our full time home need to try to fix this and get back on the road if you can please help

Expert:  RIP replied 9 years ago.


  • I can get you the timming procedures, but let me ask you a few questions here.

When you say there's no compression, have you checked with an actual compression guage?

Did this happen immedialty after the tune up? If so what parts were replaced in the tune?

Customer: replied 9 years ago.

Cap rotor wires plugs and then it turned out that he said and has set the timing, but turns out that the cap was not tight when he did this and now the motor runs like its junk and yes it happened RIGHT after he was done

when the motor is running it back fires and sputters when you idle it runs good but when you put in gear it starts the sputters and back fires

again no power when you try to go. You can get it up in speed with a good run but takes a while and wont climb hills for anything

No I am guessing I am not a expert here but dont have the money to go to the shop and have to get form NC to FL or PA

Expert:  RIP replied 9 years ago.

Alright, sounds to me like it's possible the plug wires were not put back onto the distributor cap correctly, this not only makes the engine run really bad, if at all...but greatly affects the timming. See the firing order's very important that the wires are on the cap in the right order, and going in the correct direction. The black dot represents cylinder number 1, and the firing order follows in the clockwise fashion.


Double, and tripple check the firing order until you know 100% that it's correct, this is the #1 reason for this problem after the cap and rotor are replaced. If that looks good than i've also posted the timming procedures below - you need a timming light.


  1. Warm engine to normal operating temperature (upper radiator hose hot).
  2. Place transmission in Neutral or Park. Apply parking brake and block wheels.
  3. Choke must be open.
  4. Connect tachometer and an inductive timing light to number one spark plug wire.


  • Turn off engine, disconnect 4 wire Electronic Spark Timing connector at distributor, restart engine.
  • graphic

    1. Check ignition timing and compare to specification. See: Ignition Timing
    2. If timing is not to specification, adjust as follows:

    - Loosen distributor hold-down bolt and rotate distributor until timing mark on pulley or damper is aligned with specified degree on timing scale.
    - Retighten the hold-down bolt and recheck timing.

    1. Remove test equipment and reconnect wire Electronic Spark Timing connector at distributor.


    Timing specification 6°at 550 rpm

    NOTE: Timed at number 1 cylinder with 4 wire Electronic Spark Timing connector, at distributor, disconnected.

    CAUTION: Always check the underhood emissions label (if available). Specifications and procedures on the underhood emissions label supercede all others.