set timing before engine start - Pontiac GTO Forum
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post #1 of 5 (permalink) Old 07-10-2018, 05:47 PM Thread Starter
 
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set timing before engine start

Hi, I have a 69 GTO with a 65 421 engine, trying to start the engine for the first time this summer and it will not turn over. It just cranks and it sounds like it wants to start but I just get a back fire every 10 seconds or so. My question is based around the idea that the timing may be entirely not correct because of turning the engine over by hand a while replacing parts over the winter, so it could be anywhere. I don't know how to set it without the engine running, like lining up the piston or something, I am amateur mech but many years wrenching in the driveway. The MSD ignition is "on" but after cranking it once it shuts off and I have to reset the ignition or the LED does not come back on. I have both positive MSD ignition going to the battery positive because I thought it was getting a voltage drop, its not now. Last month i did the rear main seal, pushrods and lifters, changed from 8 bolt water pump to 11 so i added a new Romac harmonic balancer, it was the old two piece, this all meant I had turned the engine over by hand many times. I've been using an MSD Digital 6 Plus with an MSD Pro Billet distributor and everything worked fine last time it ran last year. All the wiring looks good. What info may I provide to help troubleshoot? Am I on track thinking there is no sync between the new balancer, distributor and setting timing? Thank you, I am right here online for the duration if anyone can jump in. I am waaay behind driving this beast and need to cruise soon or Ill freak. Thanks, Shane
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post #2 of 5 (permalink) Old 07-10-2018, 06:30 PM Thread Starter
 
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Hi GTOForum, so I had also made sure the #1 piston was at TDC and the pointer under the distributor cap was pointing pretty close to the #1 spark plug wire, it was about 1" off, meaning looking at the timing mark for 0 on balancer was about 1" to the right. Not sure if I am explaining things properly for you experts but I am moving forward as best I can. Thanks, Shane
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post #3 of 5 (permalink) Old 07-10-2018, 07:46 PM
 
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OK, here is the stupid question, and not to insult.....you have the distributor wires running in a counter-clockwise rotation?

Wild guess, but how did you line up your timing marks on the timing gears? Early engines, like the 421, aligned timing marks with cam gear at 6 o'clock and crank gear at 12 o'clock -so they face each other. The later engines(not sure when they changed over- probably with the 1967 400) had the timing marks with cam gear at 12 o'clock and crank gear at 12 o'clock. Did this once myself and used the early alignment diagram and the best I could get was the popping through the carb and once in a while sounded like it would catch, but never would no matter how I swung the distributor. I did not pull the distributor nor know enough to check #1 cylinder for firing. It was an old beat up/rusty '68 GTO I paid $250 for and I did not know any better back in my youth, so it got parted out and scrapped - I made money on it.

When you pulled your distributor did you re-install it/aligned to its original/earlier position? If you did, you may have lined up your old distributor timing to the later engine timing gear alignment and the 12 o'clock cam gear/12 o'clock crank gear is 180 out and you may find that the engine will fire up if you put the #1 plug wire in the #6 cap position and follow around CCW in the usual firing order.

Second option, and the better, is to pull the distributor and set your #1 cylinder on its compression stroke at TDC. Then reinstall your distributor so the rotor now matches the cap wire for #1 cylinder and follow around CCW in the usual firing order.

Another train of thought is that the distributor is simply off. It does not take much to have the rotor "miss" the mark and not fire. It may seem like the rotor is lined up to fire #1 and your balancer is positioned at 9 degrees BTDC (?), but it may be more off then you might think. So double check this.

Finally, you changed lifters along with the cam. Are you using the non-adjustable torque down method on the rocker arm studs or did you go with polyloks to make the valvetrain adjustable? If you went with polyloks, it is possible that one or more valves are adjusted too tight and not fully closing, thus popping back through the carb.

Lastly, it may indeed be an electrical/MSD problem. You might want to talk to their tech department to see if they have any suggestions. I would do this if you think this to be your problem. Not sure if the LED is supposed to remain on at all times or simply come on initially to let the user know it is operating correctly. If it is supposed to be on at all times, then you could have a problem here and I would get that solved first.
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post #4 of 5 (permalink) Old 07-17-2018, 09:57 AM Thread Starter
 
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[solved]

Hi, thank you to PontiacJim for providing one of two clues needed to solve this for me. The MSD Digital 6 Plus ignition was getting 9.6v during crank so I am getting some voltage drop but still within their specs to fire a spark. After calling MSD a knowledgeable tech said try wiring 12v switched direct to battery, this solved the no spark issue. Second, PontiacJim provided the second clue, I double checked where I thought my rotor was lining up with the #1 spark plug wire at TDC, I was one distributor post off and moved them all one post clockwise, BOOM, the beast started right up, loud and nasty as ever pushing nearly 600HP on engine build alone. Thank you everyone, I learned everything there is about ignition systems, setting magnetic pickup with feeler gauge, verifying reluctor sending low voltage, and the usual purple wire on S terminal. Thanks, Shane [Cape Cod]
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post #5 of 5 (permalink) Old 07-17-2018, 06:55 PM
 
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Good job. Sounds like you have the skills to tackle the job. This is why I like doing my own work and solving for problems - great learning experience, you know the car/engine better, and if you have a problem in the future you have a baseline foundation as to where to begin your diagnosing and checks.

Should be a mover.
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