Sbc 350, running fine then doesn't want to idle while at a light. I bumped the idle up to about 950 and headed back home, car acted like maybe it was going from idle circuit to mid circuit right away( pair of 600 carters). It would squeel the tires while trying to leave the stops without much gas being given. About three times of that and I pulled over to lower the idle speed down a bit and noticed it smoking out the left pipe, grayish color kinda cleared up at a higher rpm holding throttle steady at 2000. Pulled back out towards home and got a pop that I figured was ignition, had to go up three hills and it didn't pop or run bad under load going up them. A couple blocks left to go before my street I yanked it back down into second which sent it to 3500 and it was steady, I blurped the throttle to about 4500 twice and both times the car just rocketed no bad effects. I put it in the garage for the night, tonight I was back messing with it and it's still smoking out the left pipe but while being held at a steady 2000 rpms it was nice and smooth. I jumped in to test drive and it started poping out the left side. So where to start ? I was thinking of pulling the valve cover and checking the rockers and also laying a straight edge across the rocker studs and see if one is trying to pull out. What else could I check ?
My first thought was that but why only smoke out one side. I've broken a couple stock rockers on this engine in the past couple years, one a year. Last ones I put on were the roller tip with comp cams push rods and the valve springs were shimmed to correct hight when motor was first built. I'm gun shy about rocker failure on this engine to say the least.
I had a sticking lifter that finally did in an engine a while back. It would pop every so often. One day my son was driving and the engine just locked up. One of the valves number six went clean thru the side of the cylinder. All cylinders were full of water when I pulled the plugs. Pop was caused by valve being slammed shut. You can search on my user ID to find that post. May not be your problem, but then again.
So why would you just leave us hanging man, give it up ,what was the problem ? Someone else may have the same problem down the road and if we know the cure for yours we maybe able to help someone else later.... I know alot of folks don't like SBC but alot do use them for many reasons, Sooooooooooo THANKS for the heads-up..............
Well I pulled the cover and inspected the rockers, springs, push rods and the roller tips on the rockers. Then thought about what would cause a low rpm missfire and raw fuel vapor out the pipe. Damn thing fries the tires on the higher rpms without problems, then right back to low rpm popping. So I pulled the plugs and sure enough they were fouled. I was running R43TS' in it but had the old R44T's I pulled out to go to the colder deeper reach plug. I put those in and spent a half an hour straight twisting air fuel screws, rear carb then front carb, back the idle speed down and repeat. It's currently idling at 700-725 with a smoother engine, it also has very crisp throttle response off idle too. The car always lacked good off idle jump when I switched to the dual carbs but now is damn close to the single four reactions. The only thing I can think of was the plugs were fouling and I compensated with air/fuel adjustments. I really can't remember when the last time I adjusted the mix but did it on a vaccume guage not by rpms. I orderd a set of the Ac Delco rapid fire plugs from Summit after chasing down false leads that the local parts stores had them. They are suposed to be a cleaner/hotter firing plug at low rpms. So to sum it up I just changed to fresh plugs and the damn thing runs. I think having the carbs tuned for power at the top end leaves them fat at the bottom and the plugs will only last for so long before fouling. Most of my time is spent below 3500 rpms but the thing does run great at 6000, sure don't want to be lean up there.
The Jalopy Journal
