Hello Buick folks, I'm having issues with my 65 Skylark with 300 V8. I have tuned the car up just last month, with new plugs, wires, cap, rotor. Instead of replacing the points, I went ahead and ordered a Pertronix kit from Jeg's. But before I put the EI kit in, the car ran great with the old points. The EI installation went well, and the car fired right up. I re-set the timing, which was advanced by quite a bit. I brought the timing down to spec, which reduced the idle speed quite a bit, but still it does not seem overly low, since the spec is about 550rpm. Here's my issue: once the car warms up, the idle is jittery. And, at speed, you can feel that the car isn't firing smoothly, especially when you put into it. Now, when the car is cold, it idles as smooth as glass, and, when accelerating, there is no hesitation. But when the engine is warmed up, it will hesitate when you step on the gas. Any help would be appreciated. Maybe the carburetor needs adjusted? Thanks from Sunny Tampa. Rich
Did you replace all of those things at once? Sounds like a timing issue to me if it ran great before the tune up and you didn't touch the carb. Double check the plugs and wires and make sure your choke isn't sticky.
with electronic ignition and the worn engine there is no reason to bump timing up a few degrees.. check your vacuum lines for cracks and if their are connected in proper places.
The tune up timing specs only apply if you have the original distributor installed. Unless you have owned the car since new and know it's history, you should check the distributor to see if it is original to the car. Lots of parts get changed in a 50 year old car. That may explain why the initial timing was advanced. Set the total timing to 32*, and the initial timing will end up where it needs to be. Advancing the timing will speed up the idle, retarding the timing will slow down the idle speed.
Thanks Larry, What do you mean set the "total" timing to 32*? I just used a timing light and have it set to a spec I saw somewhere on the internet, which was 2.5 degrees BTDC. When I initially went to time the thing after installing the Pertronix, the timing mark could not even be seen. As I said before, I didn't think I skipped a tooth on the distributor.... But I will replace the vacuum hoses and check to see that the choke is kicking off when warm. Thanks again, Rich in Tampa
Read this repeatedly, until it makes sense. http://www.v8buick.com/showthread.php?63475-Power-Timing-your-Buick-V8&highlight=power+timing
Total timing is the sum of initial timing + mechanical timing + vacuum advance. Since vacuum advance does not function at all at wide open throttle, when I say set the total timing, I mean set the initial + mechanical timing. Over the years, Buick spec'd different distributors in their engines. Depending on the year and engine, the distributors had DIFFERENT amounts of mechanical advance built into them. Distributors can wear out, and be replaced over the life of a car. An engine meant to be timed at 2.5* initial advance would commonly have a mechanical advance of about 30* or so. Buick engines like about 30-34* of timing at wide open throttle, so 2.5 +30 =32.5*. Now say your distributor has been replaced with a distributor out of a 71 or 72 350, and that distributor only has 16* of mechanical advance. You go ahead and set your initial to 2.5*, and end up at 2.5 + 16 =18.5*, and then you wonder why your engine runs like a pig. There is a way to set the total wide open throttle timing to 30-34*. Then it doesn't matter what distributor you have installed because the initial advance ends up where it needs to be regardless of the amount of mechanical advance built into the distributor you have. What changes is the initial advance. In the above example, your initial advance would end up at about 16*, but the WOT timing would still be 32* or so. I hope you disconnected and plugged your vacuum advance before setting your initial timing. If you simply set the ititial to 2.5* and your vacuum advance was hooked to manifold vacuum (as it should be), your timing is now retarded. Yes, it describes basics and how to set total timing.
Thanks Larry, Wow, this whole total timing thing is news to me, but I never delved into engine performance beyond basic tune-up. I see that my choke looks to be partially disconnected (a threaded nipple coming out of the bottom of the choke isn't connected to anything...would that have gone to a heat riser tube of some sort?). I'll have more time to check things out over the weekend, but it would appear that the choke may be stuck in the on position, and doesn't open up once the car is warmed up. Thanks again to all for your helpful input. I am learning new stuff, and that keeps it interesting. Rich
300 still not running right Hello gents, thanks for all your suggestions on my rough-running 300. It still runs rough despite all the stuff I've done. Here's the list of things.... *New plugs, wires, rotor, cap, coil. (Not expensive to replace all these parts, so it made sense to do it). *New vacuum lines and fuel lines, plus new fuel filter and fuel pump. *New Pertronix EI kit from Jeg's. Install went well, and the car fired right up. I re-timed the car after the EI install, and timing was way advanced as compared to the previous setting with points. I timed it to the spec of 2.5* BTDC. I could not understand the total timing thing, just give me a spec and I'll set it. Again, here are the symptoms: The car will cold start just fine, and will run great for 10 minutes. Once warmed up (170-180*) it idles rough at stop lights, hesitates on take-off, and is jittery when accelerating at speed. I checked the choke, and it pulls off just fine when the engine warms up. If I shut the car off and go into a store for 15 minutes, it re-starts easily and runs nice for a few minutes, then it's back to rough performance. Maybe I should have kept the points, and not gone with the Pertronix? Maybe I flubbed the Pertronix install? The only thing I have not done is adjust the Rochester 2-Jet. Is there a quick-and-easy way to accomplish this in a half-hour? Thanks again for any new advice you may have, I used all the previous suggestions, but not much of a change. Kind regards from Tampa, Rich
Re: 300 still not running right Rich, it's a mistake to start a new thread for the same issue. http://www.v8buick.com/showthread.php?304432-300-runs-worse-when-warmed-up! The original thread has important information that readers of this thread will miss. Are you setting the timing with the vacuum advance disconnected? The reason you do not understand "total timing" is probably because you do not understand distributor operation and ignition advance basics. Without that basic information, it's like we are speaking a foreign language. The factory service manual has a full description of what you need to know. If your engine does not have the original distributor it left the factory with, you cannot use the stock tune up specs for initial timing. They may not produce the correct timing at all RPM.
I'm sorry to have upset the apple cart of posting protocol on the small block section of the V8Buick website. It must be because I don't understand the basics of posting. Or, maybe my intention was to revive the thread to get fresh eyes on the problem, in the hopes of getting more useful suggestions, as opposed to dismissive responses. At least I do understand the basics of gracious internet interaction.
I'm sorry if I offended you, but you are wrong in your belief you will get fresh eyes on the problem. You will get new posters that don't know the history and repeat what has already been suggested. It is really difficult to diagnose a problem over the internet. It is even more difficult when someone decides that they don't understand a concept, and they give up trying. Lots of guys love old cars and want to work on them, but that requires understanding basic auto mechanics. I am willing to answer any questions you have regarding that, and I am here to help. I have been on this site since 2002. I wrote that "Power Timing" thread because I saw lots of repetitive questions regarding ignition timing. Have a look at the thread rating and number of pages. There is more to ignition timing than just setting the initial timing and forgetting it. Once you go above idle speed, ignition timing changes. It is very easy to check all of this with a timing light. Once you do, you can eliminate it as a cause and move on to other factors. It may turn out that timing is not the problem, but you have to check it.
Rich --if the moderators had seen your second post before Larry, we still would have merged the threads. So, do not blame Larry. He is one of the most gracious and helpful people on V8Buick.com.
Rich, I think much of your problem stems from today's gasoline formulation, especially if 10-15% ethanol is added. You may want to make an insulating plate (phenolic or plastic material) to go between carb and intake manifold. Richening up primary jets slightly will also help. Try to use 93 octane non-ethanol gas. Regards, John
I don't mind the merging of the threads, and again I'm sorry for making such an egregious faux pas. What I do mind is the condescending attitude of certain people on this site. OK, I'm not the Albert Einstein of auto repair, but I do have 40 years of owning and working on classic cars, some 50+ in total. Just not too many GMs, and judging from the folks here, I might go back to the foreign stuff. One car I still own is a 1975 BMW 2002. There is a web forum called bmw2002faq.com. These guys were so great in helping me get the car up and running, and I met local friends through the site, and at no time did any of those guys tell me that I didn't understand the basics of anything. One guy sent me free parts to help me out. But on this site, certain people just like to hear themselves talk, and cutting other people down must make them feel good. I encourage those people to ignore my posts and simply not respond, this post included. Finally, through a combination of my own experience, internet searches, books I have here in the garage, and the friendly posts I received on this topic before it had to turn unpleasant, I can report that the car is running very well now.
Glad you got your car running better. I don't think Larry was being condisending to you, he probably just assumed that since you didn't understand what total timing was that you didn't understand how the advance worked. By the way, to help others, what did you do to get your car running better?
Thanks for your reply TexasJohn. If you are having performance issues with your 300, I would advise that you consult other members who have more experience than myself. This is my first 300, and my first GM in more than 30 years. Suffice it to say that as I dialed around all the static, my solution came in quite clear. Cheers from Tampa....Rich
