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I have 2 problems. One is about black soot coming out of the exhaust pipe expecially when starting. It runs pretty good but if you hold up cardboard it gets black soot all over it. I have a 1961 235 in my 1952 truck. I have a new fuel pump, new GM Rochester carb from Chevy Duty, new intake and exhaust gaskets,new points and condiser. I have adjusted the only screw on the carb every which way but loose. I have set the timing I think, I can't tell for sure. I can't find the ball that is supposed to be on the flywheel but I found a hole that may be threaded where the ball may have been. Like I said it runs pretty good but not quick good enough. Maybe I need to adjust the valves? What would cause the black soot in the exhaust and the plugs? Also I have an exhaust leak that sure appears to be around the heat riser. It is turning it black also. I listened for it with a piece of hose and that is the only place I can hear a leak, it sure sounds like that is where it is coming from and with the soot there I suspect I am right. What do I do for this? I also put a new heat riser spring on it but it acts strange, is it supposed to bounce around when it idles? I had the manifold off when I put it on and test it with my torch and it appeard to work fine. Sorry this is so long but I am so close to cruising and want it to run great. Like I said it runs pretty good but am worried about the black soot and the exhaust leaks sounds like crap. :mad: Any help would be greatly appreciated.
Thanks

Sounds like you need to rebuild or replace the carb. The valves don't have much to do with soot.

I would make sure the dwell and timing are spot on, first, in that order. I have a four cylinder motorcycle that has points and 2 coils (one point set and one coil for every bank of 2 cylinders), and you can tell if the points are out of adjustment because cylinders 1 and 4 run too rich (retarded) and 2 and 3 run too lean or even detonate (points are on a plate opposite each other so the timing slips as the points wear). A dwell that isn't long enough (point gap too big) or timing that is too retarded will cause the engine to run rich and the plugs will foul, compounding the situation. Expect a little soot when the engine is cold but you shouldn't get much once it warms up. You did read another thread on the board about the right sight hole being above the starter, right? I thought so. The ball can fall out, so it may be that your hole is the right marker. Best of luck.

Thanks Josiah
Yes I did use the hole above the starter, probably one of the only things I have done right. I set the new points to 19 according to another thread I read here. It said to set new ones to 19 used ones to 16 I think. Is that correct? As far as timing goes I don't see any marker indicating advanced,would that be to the right of the pointer. I set is a little to the right of the pointer, I hope that is correct. I don't get the black soot after it is running for a short time. However I do notice that the top gasket on the carb is wet, I would think that maybe I need to set the float. What do you think?
Thanks again

Well, the rotpot carbs always seep a bit around that gasket. I would check the mixture by reading the plugs. If they are black and sooty then you are too rich. I don't remember if right or left on the flywheel is advanced, but the distributor advances by rotating counterclockwise. The points should be 0.019" new, and 0.016 used. (I actually like 0.013 better for more dwell)
The rich condition may be caused by a sticky or faulty power valve in the carb, sometimes they are not rebuilt overly well or they have weak springs. You need to be somewhat familiar with how they work to test them. The little screw on the carb is the idle mixture screw. The best way to set it is with a vacuum gauge connected to the wiper port on the manifold, just adjust it for maximum vacuum at idle. If you don't have a gauge, turn it in (lean) slowly until the engine starts to lope or stumble and then turn it out 1/4 turn. If it's too far out it will idle too rich.