305 timing at 40+ degrees - El Camino Central Forum : Chevrolet El Camino Forums
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Old 10-26-2019, 11:46 AM
Rlbeaver Rlbeaver is offline
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Default 305 timing at 40+ degrees

I have an 80 Elco with the 305, entire ignition system is new except plug wires. recently had it retimed as I originally had a broken timing light and had to do it by ear. when initially checking it the timing light showed just over 40 deg when dropped back down to 12 the idle had to be increased. when driving after it warmed up the vehicle was a total dog, would not pick up very well at all, and even when easing into the throttle once you went wide open it would run really rought and die. also when letting off the gas to coast it would backfire severely, and even dieseled for about a min after shutting it down and had 2 big bacfires out of the back and some popping out of the carb too. also I have shorty headers on the vheicle and both collectors where glowing after driving for a few min on the highway. When driving on the streets I had to ease into the throttle to keep it from poping and backfiring. When I got it back home I moved the timing back to roughly where it was set previously around that 35-40 deg mark and it runs like a champ again.
I am wondering if maybe someone has put a cam in this car and not degreed it properly or is there another explanation for this that anyone else has run into. normally I would say the car should barely run at 40 deg timing...
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  #2  
Old 10-26-2019, 12:12 PM
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Did you check initial timing with vacuum advance disconnected?

Joe
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Old 10-26-2019, 12:47 PM
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initial timing with vacuum disconnected before we reset it was 41 deg, we backed it off to 12 and that is when it started running terrible. after getting it home I eye balled it and put distributor back to where we started and now it seems to run great again. I am assuming timing at this point is between 35-45 somewhere but not sure as I didnt have a timing light at home to check it.
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Old 10-26-2019, 01:06 PM
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I'm glad it's running great again. Only thing I can think of is maybe the balancer has shifted? I've seen it happen once. I come from the school of if it works be happy. Maybe someone else has a better idea, but I'm out. Good luck!

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Old 10-26-2019, 01:13 PM
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need to double double check the timing tab 0* mark with the piston at TDC..
.
glowing exhaust is retarded timing normally,, or way over rich..
.
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Old 10-26-2019, 01:22 PM
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Yeah I didnt think to check the balancer to make sure it had not shifted. I think I will worry about it when we put a new cam in it or new engine I will just plan to replace the balance just in case and see what happens.
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Old 10-26-2019, 01:31 PM
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a quick ruff check
stand a clean welding rod up in the #1 sparkplug hole [easy if you have someone hold it]
and manually roll the piston up to TDC..
then remark the 0* ..
.
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Old 10-26-2019, 01:47 PM
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good idea JJ Ill give it a shot and see what I come up with.
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Old 10-27-2019, 06:05 AM
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I would do what JJ and others suggested. Sounds like the timing mark is off..

When you have the light on, rev the motor and see if the timing goes up. Maybe somebody locked the timing and was running full timing all the time..
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Old 10-28-2019, 10:52 AM
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i know the mechanic at the 60th reunion said to run them up to 35-40 degree. Setting to what GM suggested would do as you decribe (make it a real dog).
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Old 11-02-2019, 04:05 PM
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got a update?? find anything??
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Old 11-03-2019, 06:53 AM
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Quote:
Originally Posted by Robert Jordan View Post
i know the mechanic at the 60th reunion said to run them up to 35-40 degree. Setting to what GM suggested would do as you decribe (make it a real dog).

One of the first things I do after buying a car is power time the motor. My 69 with a 78 454 likes 22 initial, 14 mechanical slowly in at 2600, no vacuum advance.
People who don't understand timing curves some times get upset when you change something other then factory. The factory setting was designed to work on cars all over the planet. Some have daily weather of -10 to 90 day in and day out.. When tuning timing, I usually start with 87 octane if the motor is 9:1 or under..
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Old 11-05-2019, 07:08 AM
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I havnt really come up with anything solid other than just run it at 40 degrees. I am planning on putting a cam in it sometime this winter if all goes well at that point we will probably replace balancer in case it has spun and then follow instructions from cam manufacturer on timing. as long as it runs as good as it does I am fine with running 40 deg timing.
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Old 11-05-2019, 08:28 AM
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SBC had 3 different damper marks/timing pointers. Maybe yours are mismatched.


http://www.crankshaftcoalition.com/w..._TDC_lines_SBC
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Old 11-05-2019, 09:15 AM
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X2 allways check the 0* first,
then the timing readings will be accurate, and make more sense..
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