won't idle - black smoke

[yttkuar]

71 Bus Problem Timeline 1776 no idle – lots of black smoke

May - spring tune up and once over – oil change, adjust valves, check plugs, change fuel lines, drive around neighborhood – it was running fine till this

first camping trip in mid-June to Gulpha Gorge campsite 6 miles from home....noticed slight sluggishness on first hill, thought it wasn't fully warmed up....was noticeably sluggish and didn't want to pick up speed after left turn on Gorge road....100 yards from campsite on the final small hill climb, it stalled and would not start again....felt like no fuel....a person helped push us over the crest and we rolled into the campsite......engine compartment smelled oil/gassy and noticed oil film on most of engine parts.....AAA towed us home (again).....parked it and next morning I prepared to push it into the garage....it started and seemed OK.... July through August, I researched on TheSamba noting the above problems.... one response mentioned the heat risers possibly plugged with carbon could stall it out...I started it and saw condensation on the riser just below the carb....felt the right riser tube, it was very hot, so was the left indicating that the riser tube was plugged. I disassembled the muffler so I could try to ream out the riser if it was plugged....it took me 5 hours the first day and 6 the second before I could work the cable on the drill to break through. I thought it never would clear. I blew a lot of air and reamed more and more soot and carbon out....put it back together and started the engine, now the right side heat riser is hot but the left side is much cooler, indicating there is circulation of air....ran it a few times more after that, not driving anywhere just running it....thought I had it fixed....

on one such day, it would not idle down, just rapid (1400+) ...I could start it but then, no idle and I noticed black smoke and heavy oil smell...figured I was way to rich so tried to adjust both mixture and idle screws....I have not been able to get it to idle,.. I can start ok but no idle, as soon as I stop revving it dies,....I took the carb off and cleaned it thoroughly (it is only a year old) thinking maybe the new fuel line had a particle in the jet stuck somewhere....put it back and no change....used a spare carb to see if it was the carb....no change.....I put a fuel pressure gauge on the line and it is at 2.5 and holds after shutoff for several minutes....thought it might be the pump, but it appears ok...still starts but will only run while revving, no idle and still carbon smoke.....

Side Note:
About 2 years ago I installed a Empi overhead oil breather kit behind the fan on the wall. I routed the hoses from the valve covers to the breather and then to the oil return on the filler cap tube. I thought that might be the source of the oil film. Not so. I decided after looking inside, what should have been a sludge filled breather, only to see that it was as dry as the day I installed it. So I returned to the factory oil bath breather. (Even the hoses from the valve covers were empty.)

I have repeated the idle and mixture screw set up of 2 ½ fuel turns and 3 on the air, several times and still cant get idle. The Throttle screw is just at the bottom step too.

I only run premium ethanol free gas.....somewhere I am missing something??? I have a new fuel pump, but since I have good pressure, it seems the pump is OK, except, could that be why I have to keep pumping the throttle? Maybe it is bad! After all I have done, I didn't want to throw parts at it, but it could be the pump. Any ideas?

[mikedjames]

This is probably too much fuel. Coming up hill, your carburettor demanded fuel to deliver power. Then when you got to the top, the fuel metering valve in the float chamber stuck open, and it started filling the engine with fuel. So it stalled out with too rich a mixture.

No amount of playing with mixture screws will fix this, a quick disassembly of the top of the carburettor and making sure the valve is clean should fix it.

And then make sure there is a fuel filter to stop the dirt getting into the carburettor ..


The general film of oil over everything is probably just general wear and tear on the engine, and blow by from worn piston rings, or the baffle plate in the alternator/generator stand is backwards or missing.

Your heat riser issue is a separate thing, and you have helped that, but you may also need to make sure you have the stock air cleaner setup with hot air available at idle, which automatically switches to cold air at WOT for power..
_________________
Ancient vehicles and vessels

1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.

1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy

[yttkuar]

Update fixed! How I got it done.
I had a good friend from our local club come by to give it a listen. He noticed #2 was missing, so removed the plug and it affirmed that it was not firing. I replaced all the plug wires and that took care of the miss. He also noticed the brake booster hose might be leaking at the connection. I took it off and temporarily plugged the vacuum port. I re-timed it, exchanged the problematic EMPI (fairly new) carb for my older carb that I thoroughly, thoroughly cleaned. I set fuel and bypass air to 2-1/2 and 3 turns out. After I first got it to idle, sort of, the next day it didn't want to idle again. I spent most of the next day trying to get back to that point, but couldn't. Then, I went back to zero and re-timed to 5 ATDC and it was no good at all so timed to 7.5 btdc and 2.5 on fuel 3 on the bypass. I also re-cleaned the right side idle jet and put it back just snugged. It started and I held it on the throttle till it was fully warmed, then I re-adjusted the throttle to barely touching the step down. I had lunch and then tried again and it held idle, although very rough and stumbling. After adjusting the fuel and bypass trying to increase idle, it made no difference. I forgot...earlier when it was holding idle I sprayed starter fluid in all the right spots and it made no difference. So, I decided that maybe I really did not set the throttle screw in enough. Every time I have turned it in to where I could just slide a piece of paper between the screw and the step down it didn't seem to help. Rather than trust the piece of paper trick, I screwed it in till I felt a back pressure on the screw driver...and then a little more. With that I was able to get it to idle at about 1000 rpm. and the rpm seem OK too. It still is not a smooth smooth idle and sounds a little slappy to me.
Next day - More good news. I re-adjusted the valves first off this morning thinking that might help the slapping sound. #3 was a little tight. It started right up and idled at 1010 rpm went as low as 900. I let it run quite a while and checked the valve cover temp when I shut it off. 1 & 2 were at 154 degrees, 3 & 4 were at 145 degrees. Yesterday, I had loosened the distributor and moved it ahead a little and that helped. I had set the static at TDC after trying 5 ATDC which didn't help. So after that first try this morning, I got TDC and set timing at 7.5 BTDC and locked the distributor at that setting. After lunch, I started it up and it did not have the same slap sound at all; more normal. I took my stethoscope and only heard a little more noise on #3. Overall, it held RPM pretty good and the temp was the same that second time. THEN I hooked the brake boost cable back up, after cutting that frayed part off. (It had a frayed and old connection, so I took it off till I could get the idle) NO leak, so I am comfortable with no leaks. Finally! Success! Thanks to advice and experience of a good club member, I think I am back on the road. Yesterday, I pulled it out and drove around the drive several times just to make sure it all stayed together. It was fine. Sarah wasn't home, so I didn't want to take it out too far in case I stalled and had to call AAA again. So, this morning I took the bus for a 11 mile shakedown going up and down grades as well as level upper speed areas. Our drive is pretty steep and that was my main concern. It handled the grade just fine. The idle was steady and may be a little high, but that is fine with me. Now...on to the yard work!

[Pruneman99]

What distributor are you running? You are setting it at random settings designed for different distributor/carb combos. You must time according to your distributor, not year of car.

Your breather box is hooked up wrong, that's why it's completely dry. You have all three sides hooked up to case pressure. You need one to atmosphere, or vacuum (intake).