Need help working out bugs before I decide to rebuild (?)

Jeremy,
Do you have a dial back light? Or a standard timing light? The lightest springs are for checking the total advance.

 

OK, see if this article I wrote for my club newsletter helps.

About 6 years ago, I wrote a Power Timing thread on www.V8Buick.com. I did this because I kept seeing lots of questions on proper ignition timing for stock and modified Buick engines. The thread turned out to be one of the most popular threads on V8, with over 500 posts, and 21 pages. It is also one of the few threads with a 5 star (excellent) rating, so I guess that lots of members have found it useful. Over the years, I have answered a lot of questions online, on the telephone, and even in person, when I could. Ive linked the thread, while answering timing questions I continue to see on V8. Some of the questions, along the way, have dealt with using an advance (dial back) timing light. With that in mind, I thought I would write something dealing with how to use this type of timing light to analyze and optimize your engine timing.


There are 2 types of timing lights, standard timing lights, and advance, or dial back lights. Both can be used to set timing, but the advance lights include a knob and degree scale on the side of the light facing the user. The degree scale typically goes from 0 to 60*. Turning the knob, while viewing the timing mark, allows the user to visually retard the balancer mark in relation to the timing tab. This comes in handy when the balancer mark is above the timing tab, and you have no degree reference. Turning the advance knob, will retard the viewing position of the mark. If you turn the knob until the balancer mark is aligned with the 0 on the timing tab, you can then read the timing right off the dial. You can use this feature to map your timing curve at various RPM. All you need is an assistant, and an accurate engine tachometer. Record your timing at idle, and at 1000, 2000, and 3000 RPM, and use the dial back feature of the light to read the timing. Remember that spring tension will determine at what RPM, the timing stops advancing, and your mechanical advance is at a maximum. Its not really a good idea to free rev your engine to more than 3500 RPM in neutral. Your neighbors wont like that either.

Setting up your total timing is easy with an advance timing light. Use the lowest tension springs available. This will make the job quicker and easier. Remember to disconnect and plug the vacuum advance. Clean the timing tab of any oil and or grease, and highlight the balancer mark with white paint to make it more visible. Also loosen the distributor hold down bolt just enough, so that you can rotate the distributor by hand. To begin, turn the knob to the degree setting that corresponds to the amount of total timing you want. When you point the light at the balancer, realize that the balancer mark will appear below the 0 on the timing tab. Slowly open the throttle. As you rev the engine, the balancer mark will move upwards. Increase the engine RPM until the mark stops moving up. That RPM will depend on spring tension. The total timing will equal what you have the timing light advance knob set to, when the balancer mark is aligned with the 0 of the timing tab. If the mark stops moving upwards, and it is above the 0 on the tab, it means you have more advance than you want. Turn the distributor clockwise to retard the timing, and try again. If the mark stops moving, and is below the 0 on the tab, it means you have less advance than you want. In this case, turn the distributor counter clockwise, and try again. Again, you want the mark to stop moving up when it is aligned with the 0. It may take several tries to get it correct. Move the distributor in small increments. Remember, the distributor is driven at one half crank speed, so one degree of distributor rotation, will equal two degrees at the crank. When you are finished, tighten the distributor hold down carefully, and recheck your timing. Change the weight springs to ones that bring your total timing in, at the RPM you want. For street cars, 2500-3000 RPM is best.

 

If that isn't clear, or you are confused about anything discussed in the above. Ask. I'll try to help. Gonna be leaving for the club Holiday Party soon, so might have to answer tomorrow.

 

It is such a simple thing to measure your total timing, yet so many guys have a problem with it. Really important to know also. Tell me where you are getting stuck, and I will try to help.

 

X2, and that is why I wrote the power timing thread. I've helped lots of guys over the years. If they are local, I just have them bring me the car, and I show them, in person. Their reaction is always the same. They say, "How could I not get that, it is so simple". Literally takes me 5 or 10 minutes to show them.:laugh: Definitely worth the effort to get it right, and know the number for sure.

 

What you need to do first is decide what total timing you want to run. If you look at most Buick timing specs, they are usually between 30 and 34* total timing. So, I would start with 32*. Turn the dial on the light to 32* Install the lightest springs you have. Remove and plug the vacuum advance hose. Loosen the distributor hold down bolt just enough so that you can turn the distributor by hand. Start the engine. Point the light at the balancer. You will probably see the mark somewhere below the tab. Slowly rev the engine and watch the mark. You should see it move up. What you are seeing is the weight moving out and advancing the timing. At some point while you are revving the engine, the mark will stop moving up, and it won't move any further no matter how high you rev it. That is the point you are looking for. The lighter the springs, the lower the RPM where this will occur. The lower the RPM, the better, because we don't want to free rev the motor any more than is necessary. It helps to have another person at this point, to hold the engine at that RPM. Then all you need to do is turn the distributor until the balancer mark is even with the zero on the timing tab. Once you do that, tighten the distributor hold down, and let the engine idle. Check your work. Point the light, rev the engine until the mark stops, and the mark should stop right at the zero, and move no further. At that point, the timing is 32*, or whatever you set the dial on the light to in step one. Shut the engine, and put a combination of springs in that get the timing in at 2500-3000 RPM, and that is near optimal for a nice street car. Leaving the light springs in will frequently result in part of the mechanical advance being in at idle speeds. You really don't want that, as it will make the RPM drop more when you put it in gear. Ideally, the mechanical advance starts a bit above normal curb idle speeds.

None of this will work if the engine has other problems like a vacuum leak, or misfire, or if the cam is in wrong. That's the problem sometimes. You end up chasing your tail because you aren't starting with a healthy engine to begin with.

---------- Post added at 02:06 PM ---------- Previous post was at 01:57 PM ----------

Not necessarily. Depends on the springs. You need even lighter springs, or, you have to rev it higher. You must find the point where it STOPS advancing. Once you find that point, you can set the total, at that point, to what you want. In the PT thread, I recommend the Crane Adjustable vacuum advance kit. It comes with three sets of springs, yellow, silver, and blue. The yellow are the lightest, and they work the best for setting the total. Then, I usually use one yellow, and one blue. That usually works pretty good, but you can mix and match the springs until you get what you want.

 

That is fine. If you are sure it stops advancing at 2500 RPM, then set the total there. 2500 isn't too high to rev the engine.

 

Very good. Remember though, that the vacuum advance will likely have too many degrees in it now. Your mechanical advance is in earlier than stock. What you should do is limit the canister to 8-10* If you like, you can hook it to a manifold vacuum source and get that extra advance at idle. The engine should like that. That way, you will cruise at 41-43* for gas mileage, but when you nail it, the vacuum advance will go away leaving you with 33* at WOT. The extra advance at idle will make it idle better, and the engine will run cooler in the summer. You can try it on ported vacuum also. See what you like better, but limit it to 8 or 10* maximum.