Slant exhaust black carbon at tail pipe?

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TF360

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Just put new exhaust on the 1974 225. She has a lot of black build up at the tail pipe. Engine runs really good, and I set my timing at 2 degrees advanced- It calls for it at 0 degrees. It is also running really cool (195 thermostat barley gets there). Recent tune up done and Carb adjusted. The cool running and extra black at the pipe indicate timing no? Thanks
 
I disconnected the Choke because I installed headers. I wonder if that will affect the Carb. It runs good. Just takes a little longer to start
 
It sounds like your mixture is too rich, not rich enough to keep it running when cold. Try To put a electric or manual choke on it and lean the carb out a bit
 
Headers= no intake manifold heat, =puddling and rich running
 
Just because the spec. calls for zero degrees initial timing does not mean that's optimal. When i had a slant six it was set at 7 at least and ran well.
 
volaredon said:
Headers= no intake manifold heat, =puddling and rich running
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Yup, running a water supply from the engines cooling system is a big help! Running no choke as mentioned well also be dumping raw fuel until she warms up. I run 12 degrees initial timing. More timing before she doesn’t want it the better start ups and efficient motor you will have. Verify timing marks on balancer with a tdc stop tool, 2 degrees is not enough to get it to run its best try giving it more timing before she pings. Once she does that take some timing out of the dizzy, change the heavy spring with a lighter one. And trail and error or you can use the FBO limiter plate.
 
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Intake needs heat. a cold intake will puddle fuel and ask the carb for more A/F. You turn it up and eventually you are running rich again. See if you can heat that intake with a block off plate and a water feed. I think youll find carb will need to be leaned out and will run better. Get the heat riser block off plate on Ebay and drill a hole in it for a barb fitting and put another fitting on the EGR block off plate over the heat port, now you got a water loop you can plumb into your bypass hose.
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The only problem I have with that is that it was running rich before the headers; however, I expected the headers to lean it out. That didn't happen though. I live in south Florida too.
 
headers will give you more scavenging but a cold intake will hamper this more. Give it a try, it costs $15. Is the intake cold to the touch after a drive? I know humid conditions can ice up an intake, yours is probably not icing but getting cool. VW guys running single carbs have aftermarket parts that add heat to their long intake tracts and they can really lean out the carbs after this as all the fuel is now making it to the carb, not suspending on the cold intake walls.
377px-Carburetor_icing_conditions.png
 
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No it's not cold to the touch. It warms up, but I will check to see just how hot it gets. Good thought
 
The primary byproducts of proper combustion are Energy and water vapor. On humid days, moisture in the atmosphere passes right thru the engine, sucking up heat to become steam, and then most of it will condense in the exhaust system and puddle in your muffler. If you don't provide drainage, acids will form in there and it will soon have holes in it. But after awhile, the exhaust moving thru, will pick it up and eject it out the tailpipe as black sooty droplets. The steam will condense in every low spot in the exhaust system.
The steam will also clean out your combustion chambers, moving the soot out the back.
I run my engine at 205
I hope you have a working vacuum advance. This will allow you to lean out the PartThrottle and cruise circuits. On the hiway, on long trips, the engine should stop producing soot, and either clean the tailpipe right out, or it will begin accumulating a hard brown deposit; either is good. But a powdery white deposit is not good.
 
Thankyou AJ- The vacuum advance is hooked up. You know, before I put the headers on, I would start the car and black sooty liquid would shoot out the tail pipe for a couple minutes. It stained my driveway. Seemed like it always stunk too much-fumes. Have a 195 thermostat in it. But she doesn't seem to get up to the 195 temp.
 
pishta said:
headers will give you more scavenging but a cold intake will hamper this more. Give it a try, it costs $15. Is the intake cold to the touch after a drive? I know humid conditions can ice up an intake, yours is probably not icing but getting cool. VW guys running single carbs have aftermarket parts that add heat to their long intake tracts and they can really lean out the carbs after this as all the fuel is now making it to the carb, not suspending on the cold intake walls.
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Been a while since I've seen a graph like that. I have hundreds of hours in GA aircraft. It could be a humid 70 deg day in the Pacific NW, doing a pre-takeoff system check, pull out the 'carb heat' and watch the RPM momentarily drop and then go higher than originally set to. Read of airplanes having engine failure because of it too. Carb ice is real !!
 
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