I have a buick V6 in a 85 toyota 4x4 that I just rebuilt. I am having problems with cold startups. It also has a miss after warm up but it is not severe. Today when I started it, I put the choke on and when it started up, the whole engine shook until I brought it up to approximately 1800 RPM. It does not like throttle at all when it is cold, you have to get into it real slow or it will bog. No problems after it is warmed up, except for a slight miss.
What does this sound like to you? I am running an edlelbrock 500 CFM carb, and it is only timed "by ear" because I can't find specs anywhere on the reccommended timing for this motor. I was told that I could adjust the timing for the highest vaccuum and back off one in/hg per 10 in/hg that it pulls, but when I did this, the initial timing was way over 16 BTDC, which didn't seem correct. If someone can help me out with this, I would greatly appreciate it.
03-18-2004 09:20 PM
With a noticable warm miss, i'd start with a compression test, providing you know that the ign system is in good shape. If you can find a shop with an old style scope, you can spot problems in a flash. Usually, given the time spent and un-necessary parts that are replaced, $30 on a scope is money well spent.
03-19-2004 12:24 AM
I believe somewhere around 6-8 degrees BTDC is in the general ballpark for those. To be entirely accurate give us the year and size of that V6. Is it auto or standard tranny?
03-19-2004 04:59 AM
It is an 85 (even fire) 231 bored .060". It is backed by a buick TH-350 tranny with a B&M converter (2500 stall if I remember correctly). I could have an ignition problem, but if it was that don't you think I would have a severe miss all the time and not just on cold startup? I will check the compression, but I think if anything I have a problem with the fuel or ignition systems and not the compression.
03-19-2004 04:58 PM
You could be dealing with the choke being set too rich. You didn't say if you had an automatic choke or manual. If auto, With the air cleaner off have someone start the car. when it starts and is running rough open the choke approximately half way and observe if the engine smooths out. If it runs better you need to lean your choke setting up. Also if auto choke, does it have a two spade type electrical connections? If so this should be hooked up to allow the choke to go to full open quicker. An overly rich choke will start to fowl the plugs also causing a rough running motor that will go away as the choke opens and the engine clears out.
If this helps check your plugs, you may have fowled one bad enough that it won't clear out and is trash. In this replace the plugs after you get the choke working right.:thumbup:
03-19-2004 07:42 PM
Here's the deal. This is the second time I have rebuilt this engine. The first time I had alot of fuel problems right up until it spun a rod bearing due to machine work that was off. I actually spotted the machine work being off after plastigauging it and I brought it back to the machine shop to have them check it and they said it was ok. The next mistake was my fault, because instead of bringing it somewhere else for a second opinion, I just put it back together. $500 mistake.
Since the second rebuild (last week) I replaced the original computer controlled distributor (no computer on the vehicle) with a vaccuum advance one. Before spinning the rod, I was constantly fouling plugs with the new carb, and I went 3 stages lean on the mixture and it was still fouling them. Since I have put it back together, the old plugs have all turned white (like they are supposed to be) from the black that they were before. I know I should have probably used new plugs, but the old ones only had about 6 runs on them before the bearing spun.
I had a similar problem before the bearing spun if I remember correctly (it was about a year ago now) with a rough idle on startup. To answer your question it is manual choke that is turned completely off when giving it gas to keep it running and it sounds like it has a mean cam in it until it warms up. I really suspect it to be a carb problem, but the carb is brand new out of the box. I am running the recommended 5psi fuel pressure regulated from a holley regulator and supplied by a holley blue pump. By the way the carb jets are still 3 stages lean which I could probably increase some although I am not getting any detonation under a load (it does seem to lack power though). I think this is my whole story, but if I left something out - Just Ask!
03-19-2004 08:01 PM
White is going to be lean. You want a tan color so your right in going one stage richer. Have you checked it with a vacuum gage for vacuum leaks? They will drive the engine nuts along with the tuner. Keep the faith you'll find the problem.:thumbup:
03-19-2004 08:18 PM
depending on the timing (not sure the best timing light setting) I can get it anywhere from about 10 - 20+ in/hg, so I don't think it is a vaccuum leak. I was just really thrilled to see that the plugs were all white because of all the problems I had in the past.
I'm really running out of things to blame for this other than my edelbrock carb. I've heard a lot of good things about them, but I've never had as many problems with a holley carb, and very seldom have I had to adjust anything other than the idle mixture screws on them for the engine to run good.
03-20-2004 06:43 AM
You are running lean. A rough idle and white plugs tells it for sure. An engine needs a much richer mixture to run properly when it is cold. You need to start choking the engine when it is cold. It will cause the engine to draw more fuel and result in a richer mixture. If that does not do the trick, you will probably have to richen the idle mixture. You should adjust the idle mixture anyway, but it should be done when the engine is hot.