602, 604 Start Up & Break In Procedure


The following is our recommendation for all new Circle Track Crate Engines from GM Performance Parts

Disclaimer: This information is merely a small part of your maintenance / engine start up procedures. Auto Clearing All Make & Performance assumes no responsibility for incorrectly following these procedures. Further, this information is by no means an exhaustive list of everything that may need done to YOUR engine.

New Engine Start-Up Procedure

 1) (Do A. on 604 only)  A.) Remove all the rocker arms, check that the rocker studs are tight in the head and reinstall the rockers properly. B.) Adjust valve lash and properly securing the posi lock. (See valve lash procedure).

2) Prime the oiling system with a pressure tank or a drill operated primer that installs in place of the distributor. It is highly recommended that one of the above mentioned are used for the initial prime. Spinning the engine over with the starter is NOT recommended and may cause early engine failure.

3) We recommend priming the engine with a 10w30 non synthetic engine oil for the initial start.

4) After the prime is complete, starting the engine as soon as possible is recommended.

5) Start the engine, check for oil pressure immediately and check for any leaks immediately.

6) Check that timing is near 32 degrees, final timing adjustments should be made after the engine has reached operating temperature (see 604/602 TIMING).

7) Run the engine at varying RPM’s between 1200 and 2200 RPM until water temp is over 180 degrees. (cover the front of the radiator to speed the warming time) TURN ENGINE OFF then proceed to #8.

8) Drain the oil and change the filter, this quick oil change removes the assembly lubes and also helps to remove any small debris that may have been hidden during the final cleaning before assembly.

9) We now recommend you fill the crank case with Joe Gibbs BR Break In Oil and use a Wix Oil Filter. The break in oil is to be run for one race only. Past that we recommended to use a semi synthetic oil for an additional race or two this will complete the break in process and insure the best possible ring seal known to us. We recommend Joe Gibbs XP7 for this.

10) Now a full synthetic oil should be installed. We recommend Joe Gibbs XP3 or XP6.
Note: Proper oil level is always critical. Call with any questions

604 and 602 Valve Adjustment
Roll the pushrod between your finger and thumb as if it were a cigar, at the same time begin tightening the adjuster nut.

The INSTANT that you feel an increase in resistance to roll the pushrod -STOP- that is zero lash.

NOTE this does require a certain amount of “feel” by the time you finish your first set you will be a pro.

Next: Tighten the adjuster nut 1/4 turn more.

Next: Tighten the set screw (Allen).

Next: With your hex key (Allen Wrench) and your 5/8 wrench turn both into the stud another 1/16 to 1/8 turn, this secures the set screw from backing out.

**Positioning of the valve for adjustment**

When the intake valve is closing - ADJUST THE EXHAUST.

When the exhaust valve just begins to open - ADJUST THE INTAKE

There are other methods but we have found this to work on all engines and leaves less room for mistakes.  **NOTE** If you follow the firing order you will only have to turn the crank a 1/4 turn between valves once you get #1 in position.

604 and 602 Timing
1) We recommend that both these engines be set at a TOTAL timing of 32 degrees. NOTE different amounts of timing may be beneficial due to different fuels, exhaust designs and carburetor choices. However, unless dyno testing is available or controlled race track testing we STRONGLY advise 32 degrees to be the number.

2) The balancer is marked out in degrees and we highly recommend using the marks on the balancer and NOT a high tech timing light with dial up advance. ( keep it simple ). **NOTE** the small white paint mark that is near the “0″ groove in the balancer means NOTHING. The groove is 0 (TDC) and actual degrees are marked on the balancer.

3) Total timing is set with the engine hot and at an elevated rpm (even with a locked distributor). The timing actually will retard and this is due to timing chain stretch, be sure to increase rpm until the timing marks become steady.

After the timing is set, align the timing marks with the engine shut off, then remove the dist. cap and validate rotor phasing. The rotor should be pointing directly at either #1 or #6, if the rotor is pointing between terminals, then the pick up coil wires are reversed and must be corrected and the timing reset.