A friend of mine just picked up a car with a mild 350 Chevy in it. It has headers, electronic ignition, and a Carter AFB carb. It runs pretty well under load both at speed and idling. The problem is that it has a slight miss when sitting at a stoplight while in "Drive" and while accelerating off of idle. If she puts the car in "Neutral" while at the light, it smoothes out a bit. The car doesn't seem to do it right after it has been started, but the problem will start to occur after the car has been run 20 or 30 minutes. I'm thinking it's an ignition problem, but I have never had a car with a SBC as I've always run straight sixes. Anyone got any ideas? I'm hoping this is a common SBC problem. Thanks!
how about vacume leaks?...check the head/intake area where the gasket goes..also check intake bolts may be loose?...Miller
Good start. I'd check for vacuum leaks. loose carb bases were common on q-jet carbs too. Then again so were worn throttle shafts. Use some carb cleaner and carefully squirt it around those areas. If the idle goes up, you found a leak. Just be careful with that stuff around ignition wires and exhaust parts.
Have you guy's done anything yet like check the condition of the plugs, cap rotor, timing etc? Might be a good place to start if you havn't yet. Then at least you will know that the ignition parts are new, and the timing is where it needs to be. I have seen caps create idle issues similar to that as crazy as it may sound.
I haven't really checked anything yet, as she just picked the car up like an hour or two ago. I'm already getting the semi-panicked phone calls as she's never had an older car before. All I really know right now is that the alternator and PS belt are loose. I'm going to pull the cap, rotor, and plugs and have a look. It's got aftermarket stuff on it, so it's possible it doesn't fit quite right. I've seen fancy wires and caps that look cool, but don't snap together too well. I'll check the EGR out too. Thanks for the replies.
Anyone else got any ideas on what I should look for? I'm kinda surprised I didn't get more responses as this is only the most common Hot Rod engine in the Universe.
Your question doesn't require SBC knowledge, it requires tuning knowledge and the fact it's the most common engine in the universe doesn't mean much. If you know how to tune a straight six, you know how to tune a V8. Realistically until you check the condition of the ignition system and look for vacuum leaks as mentioned by previous posts, you're running in circles. Cover the basics first. Good luck
Exactly. Seriously, you need to get a hands on look at what's what. The condition of the ignition system can tell you a lot. Once that area has been tended to if need be, and the problem still persists then you can dig deeper.
lxturbo2000 beat me to it. Check the wires. ___________________________________________________________________________ Like I told the kid,"Your music's not too loud, it's just like OKC, it sucks!"
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