Tuneup Messup
Thread Starter
Team Owner
Joined: Jul 1999
Posts: 26,545
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From: Huntersville NC
Tuneup Messup
Short story - Just did a tune up on my 68 L-36 and it runs like crap - rough idle and lots of visible stinky exhaust.
Long story. Car has been running pretty well but been chasing a hesitation under load so thought it might be a good idea to start with a complete tuneup. It's been 6 or 7 years anyway. Changed plugs last night, AC Delco R45XLS wow, made in USA. Old ones were R44XLS. Today changed dist cap, rotor, points and condensor and it wouldn't start. Now maybe it's the dwell on the new points and they aren't really bad, but after screwing around a bit with no luck I just put the old points back in and it started but ran really rough. Put some more old parts back on (old dist cap and rotor) and it runs a bit better - was able to set the dwell back to 30 and it stayed there, but exhaust is still smoky and idle rough, like maybe all cylinders aren't firing. I also switched the wires to an old set of braided wires. Now I will have to change the wires back, and maybe even the spark plugs. Why did I even bother?
Long story. Car has been running pretty well but been chasing a hesitation under load so thought it might be a good idea to start with a complete tuneup. It's been 6 or 7 years anyway. Changed plugs last night, AC Delco R45XLS wow, made in USA. Old ones were R44XLS. Today changed dist cap, rotor, points and condensor and it wouldn't start. Now maybe it's the dwell on the new points and they aren't really bad, but after screwing around a bit with no luck I just put the old points back in and it started but ran really rough. Put some more old parts back on (old dist cap and rotor) and it runs a bit better - was able to set the dwell back to 30 and it stayed there, but exhaust is still smoky and idle rough, like maybe all cylinders aren't firing. I also switched the wires to an old set of braided wires. Now I will have to change the wires back, and maybe even the spark plugs. Why did I even bother?
Thread Starter
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
Pro
Joined: Dec 2006
Posts: 695
Likes: 5
From: tx
By just changing the parts there should have been no improvement at worst. The ignition and fuel system on your car are very simple. I would verify point gap, dwell, timing, firing order, check the coil and fuel supply. Have you done any motor work like timing chain and gears?
Thread Starter
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
unflipping real. I changed the wires back to the black Taylor wires that were on previously and it seems to run ok... no clouds of exhaust. I will proceed with timing tomorrow. Earlier I set the dwell but did not attempt to set the timing because I thought there was something else going on (there was). I guess one bad wire meant one cylinder was not firing which gives you a very rough idle and smelly (not fully burned) exhaust. I can't tell by looking which wire(s) is bad. My fault for using old wires, but I like those braided bigblock wires.
Meanwhile, how do you calibrate a new set of points before installation? I never had to do that before - they always worked right out of the box, at least well enough for the car to start and then I adjust the dwell with allen wrench thru the distributor cap window. I really wonder if these new points are bad. They are the same Echlin points as the old ones. According to Lars, the old ones shouldn't need replacing anyway. So the only new parts that are still in the car are the AC Delco spark plugs. What a pia!!
Meanwhile, how do you calibrate a new set of points before installation? I never had to do that before - they always worked right out of the box, at least well enough for the car to start and then I adjust the dwell with allen wrench thru the distributor cap window. I really wonder if these new points are bad. They are the same Echlin points as the old ones. According to Lars, the old ones shouldn't need replacing anyway. So the only new parts that are still in the car are the AC Delco spark plugs. What a pia!!
Pro
Joined: Dec 2006
Posts: 695
Likes: 5
From: tx
You can't preset or calibrate the points before installation. Typically you'd set the point gap when you install them .... off hand I don't recall the point gap but I think it is 0.018". The gap is set with the high point of the cam on the distributor shaft opening the points. This allows you to start the car and set the dwell (other car makes don't have the luxury of setting the dwell like a GM car with the allen wrench thru the door on the cap so setting the point gap is critical on them). For grins you might want to inspect the points visually to see if they are burned. You an check the wires when it is running by pulling one off at a time to see how the rpm changes and putting it back on (insulate yourself though). Once you get this thing running check the timing to see if it stays set or if it floats around.
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Thread Starter
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
I can't figure out why the car would not start with a brand new out of the box set of points. I put them in/ took them out twice. Both times car started with old points but not new points. The parts are nearly identical (same Echlin part #). I have done stupid stuff in the past like leave out the rotor. Today I forgot to reattach the ignition wire to the coil (so no cranking first try). But I swapped in/out the new points twice and checked everything. Car ran with the old set but would not start with the new set. Not even a hint of running, just cranking.
Melting Slicks
Joined: Mar 2007
Posts: 2,520
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From: Hinckley OH
Points should be gapped when they are installed. The rubbing block on the points should be set on one of the high points of the cam shaft and the contacts on the points should be set .019 apart (if I remember correctly from 35 years ago). The old timers trick if you don't have a set of feeler gauges is to use a matchbook cover. That will get you close enough so the engine will start, then you can use your dwell meter to fine tune it. The other thing I have seen cause a no start with new points is if the condenser wire is grounded to the distributor body.
Drifting
Joined: May 2003
Posts: 1,634
Likes: 2
From: Melbourne, Victoria, Australia, the World
I have had problems with new points not working, there was an oxide or protective coating on the contacts which need to be cleaned off before installation. Check across the points for continuity with a meter.
Thread Starter
Team Owner
Joined: Jul 1999
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From: Huntersville NC
Thanks for the suggestions. At this point it becomes an academic exercise - which part(s) is(are) bad? - and I don't have the stamina to check everything. It is 100 degrees here and the garage is hot! 
I can't remember if I ever tried the new points with old condensor, or new condensor with old points. If I swap the wires again, maybe I will do them 2 at a time. Eight wires, one at a time, eight starts... might kill me or the battery 76ray - I remember that procedure for installing new points, but I never had to do it before; they always worked well enough to start the car right out of the box. Electricity is conducted across the points.
Now that it seems to run ok with the only new part being spark plugs, I am going to first check dwell again and set the timing, and make some minor carb adjustments. Then, if it is running well, and if it cools off a little and I get bored, I might try changing ONE thing at a time to identify what is good and what is not.
I can't remember if I ever tried the new points with old condensor, or new condensor with old points. If I swap the wires again, maybe I will do them 2 at a time. Eight wires, one at a time, eight starts... might kill me or the battery 76ray - I remember that procedure for installing new points, but I never had to do it before; they always worked well enough to start the car right out of the box. Electricity is conducted across the points.Now that it seems to run ok with the only new part being spark plugs, I am going to first check dwell again and set the timing, and make some minor carb adjustments. Then, if it is running well, and if it cools off a little and I get bored, I might try changing ONE thing at a time to identify what is good and what is not.
Last edited by PRNDL; Jul 7, 2010 at 02:34 PM.
Burning Brakes
Joined: Aug 2005
Posts: 1,164
Likes: 1
From: Europe, France
If you changed the dwell, you also changed the ignition timing.
And if you changed the points, I suppose the old points were... old !
So, I don't see why you could start your engine with old points and not with new ones, except if they are faulty.
If I were you, here's what I would do :
I would keep the old spark plug wires for the moment. One thing at a time.
Then I would first try to know why the new points are not working properly : set the points gap, try to start your engine, if it works adjust the dwell, then the timing.
If new points still refuse to work, go back to the shop and pick up a new set. Sometimes new parts are junk...
Then try to replace the spark plug wires with the new ones, one at a time. You can also check for continuity with an ohmmeter.
And if you changed the points, I suppose the old points were... old !
So, I don't see why you could start your engine with old points and not with new ones, except if they are faulty.
If I were you, here's what I would do :
I would keep the old spark plug wires for the moment. One thing at a time.
Then I would first try to know why the new points are not working properly : set the points gap, try to start your engine, if it works adjust the dwell, then the timing.
If new points still refuse to work, go back to the shop and pick up a new set. Sometimes new parts are junk...
Then try to replace the spark plug wires with the new ones, one at a time. You can also check for continuity with an ohmmeter.
Thread Starter
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
HURRAH!!! Finally got it back to the way it was before I started messing with it. I set the dwell to 30, confirmed timing was spot on but was still getting slightly smell exhaust and a backfire even at idle. (Checked a few other things including timing, but this time timing light wouldn't stay on... ah ha! not firing properly?) This is after reinstalling old components except spark plugs. So I figured I better look at the plugs. The new ones were all black and fouled, but I was thinking this is probably a symptom of the problem rather than the problem. So as I was carefully reinstalling the OLD spark plugs (they were in good shape, just some brown, no black, no white) I discovered a bad #3 wire. The metal clip inside the wire that fits on the spark plug was missing. So I replaced that wire with a nonmatching but working old wire and everything seems to run pretty much the way it did before I started this ill fated tuneup. So I have 8 fouled plugs, a new set of points that the car won't start with, a new condensor (the only new part that is on the car), new distributor cap and rotor on the shelf.
Next week maybe I will change the oil!!
(they were in good shape, just some brown, no black, no white) I discovered a bad #3 wire. The metal clip inside the wire that fits on the spark plug was missing. So I replaced that wire with a nonmatching but working old wire and everything seems to run pretty much the way it did before I started this ill fated tuneup. So I have 8 fouled plugs, a new set of points that the car won't start with, a new condensor (the only new part that is on the car), new distributor cap and rotor on the shelf. Next week maybe I will change the oil!!
Last edited by PRNDL; Jul 11, 2010 at 07:08 PM.
