New Motor break In ASAP HELP

[Raul_C4]

Trying to start my new Motor for the first time just have headers on not exhaust yet.
When I turn the key a loud pop or bang almost like a M80 or gun shot , which I consider back fire maybe . Is it okay to keep turning the key and see if she starts up or is something critically wrong please help ASAP ..

 

[hcbph]

IMO how much damage do you want to do? Anything totally out of the norm is grounds to stop and find out what's wrong IMO. Personally I'd start with the distributor and timing.

 

[DonB]

DEFINITELY, check timing and be SURE firing order and distributor rotation(clockwise) is correct.

Firing order is 1-8-4-3-6-5-7-2. #1 cylinder is the front left on the engine and should correspond to the plug wire on the cap pointing toward #1 cylinder. The rotor also must be pointing to #1. If you have that right, I'd guess you may have a few wires in the wrong sequence. It's easy to do, especially the way the plug wires wind around the engine.

If you need more instruction or help let me know and I'll be glad to help you out.

But do NOT proceed without addressing the problem. Loud "Bangs" are NOT just a little out of time. They are ENGINE DAMAGE(bent valve, broken piston) type of out of time.

Raul, are you still working with that aftermarket distributor and coil? Even so....It doesn't matter much, because the firing order and distributor rotation does NOT change.

 

[Raul_C4]

Thank you for the help , I checked the wires they were good so I found out by a buddy of mine that my TDC wasn'the correct , I'm about 180° off. I had installed a summit balancer and ithe doesn't have any marks unless I missed them .

 

[DonB]

Thank you for the help , I checked the wires they were good so I found out by a buddy of mine that my TDC wasn'the correct , I'm about 180° off. I had installed a summit balancer and ithe doesn't have any marks unless I missed them .

If you have no timing marks to go by, How are you determining TDC on the compression stroke.? You can't guess at this. The engine makes 2 complete revolutions for 1 combustion cycle. Each piston goes up and down 4 times. Thus a 4 cycle engine. The 4 cycles(or sequences) are intake, compression, ignition and exhaust. That's 360* per crankshaft revolution, times 2. That totals 720* and you need to be correct within 10* of that for it to run correctly. That is the spark firing when the piston is at Top Dead Center on the Compression stroke. PERIOD!

Sorry to say this, but , you are going to great lengths to circumvent GM's years of design expertise. FOR WHAT? Are you racing a Pro-Stock? If your set-up can't reliably determine and set basic engine timing, it isn't worth the effort. At least use a stock balancer to determine TDC.

There is a way to determine TDC without timing marks, but it is difficult with the engine assembled. If NEED BE PM me and I'll explain it to you.

 

[Hot Rod Roy]

Step #1 for starting a newly assembled engine: Be sure ignition timing is correct! Dist. rotor on cyl #1 position, and vibration damper timing marks at TDC (or 6 deg. BTDC) on compression stroke!