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Topic Review (Newest First)
11-07-2019 08:02 PM
87ls5.3 JJ, I hear ya, but the original post says 305. Has anyone ever put Hyper-glass pistons in a 305? And you're right about knock sensors being better than our own sensors. I'm thinking this motor has a timing mark issue and the welding rod trick would confirm this but a 305 that runs great with the timing questionable? I say enjoy!

Joe
11-07-2019 02:33 PM
JJLT1 you can put the welding rod in #6 hole if its easy-er to get to,
1 and 6 are up at the same time...
.
timing lights are cheap compared to pistons..
especially with most motors getting Hyper-glass pistons now days..
with a louder than normal exhaust, or stereo you wont hear the noise,,
and a knock sensor can hear it way before we can..
.
11-06-2019 06:06 PM
87ls5.3 Butt in seat test and breaks the tires loose with ease at lower speeds is where I quit worrying about the timing. I bought a timing light in the early 80's and since the mid 80's I'm not sure where it is. I've used the "butt in seat" test since then and just advanced the timing till it made some clatter accelerating then backed it off a couple degrees and called it a day. I'm sure someone might object to my simpleton way, but back to, "breaks the tires loose with ease at lower speeds"?

YMMV.......

Joe
11-06-2019 08:45 AM
Rlbeaver I have not tried welding rod trick, or finding TDC on one yet, I will likely have to pull headers to get to it, or possibly use coat hanger and bend it around header. for now it seems to be running good according to the butt in seat test and breaks the tires loose with ease at lower speeds. I will update once I get a chance to sort this out, currently having to put a clutch in family members hyundai not near as much fun as working on the elco...
11-05-2019 06:29 PM
hotrodelco I have the same thing going on with a GM crate engine that a customer brought me.
When I found out the pointer was off, just tuned it by ear and seat of the pants.
11-05-2019 01:43 PM
JJLT1 have you tried the welding rod trick yet ??
11-05-2019 01:01 PM
Rlbeaver new distributor with cap rotor and ignition coil and hei module all accell. got it for free from a buddy that had it still in box just sitting. as for the advance I have moved it manually and it seems to move freely and spring back just fine, i have not checked advance with vacuum pump yet. I will check to see if idle changes with vacuum hooked up or not and see what I come up with.
11-05-2019 10:25 AM
fauxrs Couple of questions I haven't seen yet.


The emissions sticker for the 80 Camino with the 5 litre (305) call for 6 degrees @ 500 rpm (with the vehicle in drive). You say its at 41 degrees with the vacc advance disconnected.


Oddly enough this is almost exactly the total timing the oem system was designed to provide. In 1980 the LG4 in the El Camino had 6 degrees initial, 20 degrees mechanical (@ 3800 rpm) and 16 degrees vacc (@40 kPa about 12 in. mercury) [6+20+16 = 42] this leads me to believe your system may have a stuck advance system.




You say entire ignition system is new except plug wires: by this you mean out-of-box new, not just new parts installed into old distributor?
  • If so, whose distributor?
  • What rpm is the motor at when you set the timing?
  • Does the rpm climb when you hook up the vacc advance cannister?
  • Have you checked the timing with it connected?
Now a few things to check, most of which assumes an old distributor with new parts:

  • Remove the cap and rotor and examine the weights, are they up against the center pole of the distributor or are they slightly extended, when you pull the weights out do they spring back to the center of the distributor. What we are looking for is sticking advance weights. If the advance weights are going full advance the moment it starts then yes dialing it back to 12 degrees would make a dog. Because 12 degrees would be your full advance.
  • Test the vacc advance with a hand held vacc pump, with the engine idling and a timing light on, pump the hand pump slowly and watch the timing mark, note how much vacc was introduced at the hand pump and note how many degrees of advance at that vacuum. If nothing is added then either the vac advance is broken or the breaker plate in the distributor is stuck.
To best check this you will need the vacc hand pump, and a decent dial back timing light. also a vacc guage to determine you manifold vaccum at idle.
11-05-2019 09:15 AM
JJLT1 X2 allways check the 0* first,
then the timing readings will be accurate, and make more sense..
11-05-2019 08:28 AM
Jima SBC had 3 different damper marks/timing pointers. Maybe yours are mismatched.


http://www.crankshaftcoalition.com/w..._TDC_lines_SBC
11-05-2019 07:08 AM
Rlbeaver 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.
11-03-2019 06:53 AM
pitts64
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..
11-02-2019 04:05 PM
JJLT1 got a update?? find anything??
10-28-2019 10:52 AM
Robert Jordan 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).
10-27-2019 06:05 AM
pitts64 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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