Tried to set timing, can't seem to get it to work

Tiny
COPPERAZ73
  • MEMBER
  • 1985 CHEVROLET TRUCK
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 100,000 MILES
I have a 1985 chevy c10 truck, which had a 305 engine and I put a new 350 engine in it. I am still using the harmonic balancer from the 305. Since I've been told that the timing mark on the 305 will not work, I used a piston stop to turn the engine on the compression stroke until it stopped, made a mark, turned it the other way until it stopped and made another mark, then split the difference and put a new mark on the harmonic balancer, which was about an inch off from the original mark on the balancer. On the 305, the timing plate was welded to the middle of the timing chain cover, but on the 350 the timing mark is on the side, held in place by two bolts on the timing chain cover next to the power steering pump. I had the valve cover off when using the piston stop so that I could see the intake valve open, to be sure that I was on the power stroke. Then, when the new mark was lined up with the zero mark on the plate, I dropped the distributor in with the rotor pointing at cylinder number one (I am sure it was #1, it was marked on the intake manifold). I managed to get the engine running and put the timing light on spark plug wire #1 and pointed the light at the balancer and the timing mark was nowhere to be seen. This has happened to me before on other chevy small blocks. It doesn't make any sense to me, if the timing mark is at zero, when the #1 wire fires, then the light should flash at the right time and I should see the mark, but I don't. I also blocked off the vacuum advance to the distributor, so the vacuum is not throwing it off. The truck runs, but not as well as it should and I can hear the engine missing sporadically. I put in a new dist, coil, wires, and plugs so it should not be any of those causing the problem. I think the problem is the timing, possibly it is something else, however if I can't get the engine to flash on cylinder number 1 like it is supposed to then at the very least I cannot eliminate timing as the problem. Later on, I took the distributor out and put it back in. The rotor was not pointing at cylinder #1, but it was pointing at the wire for spark plug number one. Anyway, it can't be too far off because it runs pretty well that way. After all, as long as the #1 spark plug fires at TDC for cylinder #1, as far as I know it does not matter if the rotor is pointing at cylinder #1 and it didn't work any better when it was pointing at cylinder #1. Just out of curiosity, I moved the timing light from wire #1 to all the other ones, just to see if the mark lined up at one of them but it did not.
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Wednesday, April 15th, 2015 AT 4:26 PM

6 Replies

Tiny
COPPERAZ73
  • MEMBER
One more thing, don't say the problem is with the computer because this truck does not have a computer.
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Wednesday, April 15th, 2015 AT 5:10 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
I can see why you're confused. It doesn't make a lot of sense. If it is running, you must be right or at least extremely close. I do, however, have a couple questions. Most of your post refers to pointing the rotor toward the number 1 cylinder. Then you mention you pointed it toward the number one plug. Later, you mentioned that "The rotor was not pointing at cylinder #1, but it was pointing at the wire for spark plug number one." That is the way it should be done. Is that what you're doing? Also, do you know what year the 350 is?

I have to be honest, if it is starting up and running okay, other than an occasional misfire, you have to have the timing right. The way I have always done it was to simply remove cylinder 1 plug and carefully place a screwdriver in the cylinder and turn the engine by hand. When the screwdriver peaks and starts to drop, I know that is TDC. Next, I install the distributor with the rotor facing the #1 plug wire on the cap and confirm that the firing order is correct. Once that is done, I can then time the engine.

Sorry, but like you, I find it confusing. Not being there with you makes it more difficult, too. Let me know if what I explained makes sense and if it what you have already done.
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Wednesday, April 15th, 2015 AT 5:52 PM
Tiny
COPPERAZ73
  • MEMBER
Ok, the engine is the right 350 engine for my truck, which is a 1985 truck. The old engine was a 305. I bought it online for that vehicle and that is what they sent to me. In regard to your question, at first I put the dist in pointing the rotor to the number one cylinder and at the same time it was pointing toward the number one cylinder spark plug wire, when the cap was on. Later, I had to remove the dist and put it back in, and in order to avoid messing with the oil pump, I put it in not pointing to the number one cylinder because that Is where the dist dropped in all the way so I did not have to try to turn the oil pump so it would drop in all the way. However, I made sure that when the cap was on, it was pointing to the number one cylinder spark plug wire, because I knew that it should work that way. The dist does not really need to point at cylinder number one, the important thing is for it to point at the #1 wire when the #1 cylinder is at TDC. I know that cylinder 1 was at TDC. However, when I use the timing light the timing mark is nowhere to be seen. However it is not even close to #1. I am working on a way to find out how far off it is, and will let you now when I do that. The truck is running, but the timing is off because it is clearly not running well. It may be close but it is not right on where it needs to be to run the way a brand new engine should be running.
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Thursday, April 16th, 2015 AT 3:37 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Years ago, if I was having issues with a timing light, using a tach, I would turn the distributor to where the rpms peaked and started to drop. At that point, I would back the distributor off maybe 1/4 inch. That would always put me within 2 degrees of the suggested timing. The interesting thing is, if it is running okay, and it sounds like it is, the #1 plug wire should fire near TDC and that isn't happening. I am going to speak with a friend and see what he suggests. The ONLY thing I can think of at this time is the marks you made are not correct, but I know you said they are.
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Friday, April 17th, 2015 AT 5:35 AM
Tiny
COPPERAZ73
  • MEMBER
Well, I don't have a tach so I can't use that idea. I could use a vacuum gauge or just time it by ear, but my question is about why the timing mark is not in the right place. I did some measuring and it appears that the mark that I made, which I am sure is in the right place, is about 3 1/2 inches (not degrees) advanced on the balancer compared to the timing plate. Clearly if it was really that advanced, the truck would not run. It is running ok right now, but not anywhere near the pep a new engine should have. I think it needs to be retarded a bit since I think it is pinging under load, so I'll try that, but that still does not explain why the timing mark is off so much. It looks like you don't have the answer any more than I do and I'm going to just have to set the timing as best I can.
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Friday, April 17th, 2015 AT 4:03 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
I have to be honest, I don't. Nothing makes sense. Based on what you said (3 1/2" off from TDC), it shouldn't run. However, you and I both know if you are getting spark on that cylinder, the piston can't be that far from TDC. The only thing I can say is the mark is wrong, but you are confident it isn't.
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Saturday, April 18th, 2015 AT 8:09 PM

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