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goodwrench9124
goodwrench9124, ASE Certified Technician
Category: Chevy
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How do I set the timing on an 86 blazer with a 305

Resolved Question:

After installing a new timing chain and gears I am having trouble setting the timing. I have tried get6ting #1 at TDC but I think I keep getting it on the exhaust stroke. I have tried several combinations with the crank,cam and rotor and still no luck. Can you explain step by step what I need to do to get er done?
Submitted: 9 years ago.
Category: Chevy
Expert:  goodwrench9124 replied 9 years ago.

Hello, i have included all the info you should need to install dist. and set timing properly. i hope this was helpfull.

UNITS W/INTEGRAL COIL

Removal

  1. Disconnect electrical connectors from distributor cap and disconnect 4 wire EST connector. Carefully bend connector locking tabs away from housing by hand to prevent damage to locking tabs.
  2. Remove distributor cap assembly leaving plug wires connected and position cap aside.
  3. Remove No. 1 spark plug, crank engine until compression pressure can be felt in No. 1 cylinder, then slowly rotate crankshaft until timing marks are aligned at TDC on compression stroke for No. 1 cylinder.
  4. Disconnect battery ground cable, then mark position of distributor body in relation to engine and position of rotor contact in relation to distributor body.
  5. Remove distributor hold-down bolt, raise distributor noting rotor rotation, place second mark on distributor housing to indicate position where rotor stops moving, then remove distributor. Do not rotate crankshaft with distributor removed from engine.

Installation

  1. Ensure No. 1 cylinder is at TDC on compression stroke as outlined in removal procedure.
  2. Align rotor with second mark made in step 5 of removal procedure.
  3. Insert distributor into engine, aligning body with mark made on engine prior to removal, then seat distributor in engine. With distributor fully seated, marks made in step 4 of removal procedure should be aligned. If distributor will not seat against boss on engine, oil pump driveshaft may have to be rotated slightly to allow proper installation.
  4. Install hold-down clamp and hand tighten retaining bolt.
  5. Reverse remaining procedure to complete installation, then adjust ignition timing as outlined.

UNITS W/REMOTE COIL

Removal

  1. Disconnect distributor harness and feed wire connectors from ignition coil and disconnect EST connector.
  2. Remove distributor cap leaving plug wires connected and position cap aside.
  3. Remove No. 1 spark plug crank engine until compression pressure can be felt in No. 1 cylinder, then slowly rotate crankshaft until timing marks are aligned at TDC on compression stroke for No. 1 cylinder.
  4. Disconnect battery ground cable, then mark position of distributor body in relation to engine and position of rotor contact in relation to distributor body.
  5. Remove distributor hold-down bolt, raise distributor noting rotor rotation, place second mark on distributor housing to indicate position where rotor stops moving, then remove distributor. Do not rotate crankshaft with distributor removed from engine.

Installation

  1. Ensure No. 1 cylinder is at TDC on compression stroke as outlined in removal procedure.
  2. Align rotor with second mark made in step 5 of removal procedure.
  3. Insert distributor into engine, aligning body with mark made on engine prior to removal, then seat distributor in engine. With distributor fully seated, marks made in step 4 of removal procedure should be aligned. If distributor will not seat against boss on engine, oil pump driveshaft may have to be rotated slightly to allow proper installation.
  4. Install hold-down clamp and hand tighten retaining bolt.
  5. Reverse remaining procedure to complete installation, then adjust ignition timingas outlined.

 

 

Expert:  goodwrench9124 replied 9 years ago.

IGNITION TIMING PROCEDURE

  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.

 

graphic

Connect tachometer and an inductive timing light to number one spark plug wire.

graphic

Disconnect and plug distributor vacuum advance hose.

graphic

Customer: replied 9 years ago.
I currently have the chain and gears installed. I have previously rotated the cam until the first valve on #1 has opened the closed leaving the mark on the gear at 6 Oclock. I then rotated the crank until I thought it was on compression leaving the crank gear mark in the 12 oclock position. I then installed the chain and put the rotor towards #1 wire on the dist cap. What am I doing wrong?
Expert:  goodwrench9124 replied 9 years ago.

it sounds like you have the timing gears set correctly, here is a picture of gears set right. but with the gears lined up this is not number one compression stroke. here is some info on this.

graphic

Fig. 34. The valve timing marks shown in Fig. 34, do not indicate TDC compression stroke for No. 1 cylinder, which is used during distributor installation. If distributor was removed, install timing chain and sprockets, aligning timing marks, Fig. 34, then rotate engine until No. 1 cylinder is on compression and camshaft timing mark is 180°from valve timing position shown in Fig. 34. Install distributor.

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