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So last few months my 226 has been hard to start hot, small amount of black smoke when labored, and black soot on ground on first start of the day. So I think I am running rich. Seems to be more fumes than normal also.
First I changed the Holley 847 power valve and gasket and put the accelerator pump in summer driving position, no help. Then I installed a freshly rebuilt carb this weekend, nos accelerator pump, no help. Tried to adjust idle mix with vacuum gauge. I turned it in until sagged, then back out to highest reading of about 20. Slight tremble of needle. And no matter how far out I back it out, no change, which doesn't seem right, shouldn't it sag on the other end also?
Plan on changing the coil this weekend along with the distributor vacuum advance and new vacuum line. Checked timing and I am pretty close, maybe 1/2" off timing mark?
Turning it out beyond ideal should set it into "rich roll", a cyclic speed variation.
If your vacuum advance unit is dead, that's probably the reason for the soot. You aren't getting advance that you normally would. Did you do much to the distributor? On the V8's there is a tendency for crankcase sludge to build up in the bushings of the distributor, to the point the points plate can't move even with a good vac advance unit. Worth spending some time on it.
No work on distributor at all, and if the rubber advance diaphram is like the other rubber on the truck it is rock hard and maybe torn. I did a tongue test when I first got the truck but I was a real novice then.
Would it make sense also that the lack of good advance would be causing me to run hotter than ideal and maybe putting me over the edge in summer and causing vapor lock, especially with the 180 stat? And that extra heat and old coil making for weak spark to boot? I have noticed I am running a little hotter all of a sudden.
Yes to all the above. Timing is the #1 problem with flatties running hot. The diaphragm in the vac advance is metal, but they still fail pretty frequently. But check for free movement of the points plate first. It should move with finger pressure and return quickly when released.
I have a new vacuum advance and nors coil coming. Last night in preperation I took the carb apart to put new gaskets in. Upon inspection I discovered that my accelerator pump piston rubber had come off and was lodged over the check ball. I put a new piston in and it runs like a champ again. Not sure how or when that happened but on the test run I had no smoke.
First of all, Dixie did well at the local benefit show today. Scored a top 25 trophy. Wished we could have come to truckstock but my work travel schedule didn't allow it. Next year......
Secondly, carb is still running rich. Pops a little coasting downhill and a black puff when starting on a hill. To get more lean, I should be turning the mix screw counter clock wise? I turned it clockwise until it sagged, then counter clockwise till it sagged, then set it in between. Idle rpm is about 490 and engine runs nice, just trying to cure those minor problems.
