I had a stream of smoke coming out of this area. Is there a way to replace whatever seal that’s there or is it time for a rebuilt unit?
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That little boot will come in a carb rebuild kit but that will not affect your vacuum.
Where are you pushing the smoke in from?
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It's very unlikely that's actually the source of the leak and where smoke is escaping; it would require a very circuitous route to escape - but if it really is leaking from that area, a rebuild is definitely in order.
Don't get a generic rebuild if you end up going that route. Contact one of the MUD carb gurus
Don't get a generic rebuild if you end up going that route. Contact one of the MUD carb gurus
Mark W
Yep, it's true. I just don't care that much.
Carbs do not have smoke inside them. Nor do they have pressure.
Mark...
Mark...
Could be the carb to intake manifold gasket. Maybe try giving the four nuts holding the carb down a bit of tightening? They don't need much torque under normal circumstances.
I had a conversation with JimC just the other day after noticing the exact same issue on mine (smoke billowing from the same area while looking for a vacuum leak. He strongly recommended a rebuild and recommended this repair kit, which I picked up from Rock Auto: WALKER PRODUCTS part # 15829A. It comes with the leather accelerator pump plunger, although there's a diaphragm that's wrong for these carbs (I checked mine and it was in good shape so I'm fine with that).
Jim confirmed that while it makes sense that the accelerator pump is an unlikely place for a vacuum leak, it is part of an idle circuit that can jam up and be the source of a big leak, so best to just rebuild.
He also strongly encouraged me to rebuild my own carb instead of sending it in, largely because he said it's a fun job for a reasonably inclined person and he's at least 3 months backlogged
Jim confirmed that while it makes sense that the accelerator pump is an unlikely place for a vacuum leak, it is part of an idle circuit that can jam up and be the source of a big leak, so best to just rebuild.
He also strongly encouraged me to rebuild my own carb instead of sending it in, largely because he said it's a fun job for a reasonably inclined person and he's at least 3 months backlogged
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- #12
Thank you, Albert110. I do appreciate your response and all the information. Very helpful.I had a conversation with JimC just the other day after noticing the exact same issue on mine (smoke billowing from the same area while looking for a vacuum leak. He strongly recommended a rebuild and recommended this repair kit, which I picked up from Rock Auto: WALKER PRODUCTS part # 15829A. It comes with the leather accelerator pump plunger, although there's a diaphragm that's wrong for these carbs (I checked mine and it was in good shape so I'm fine with that).
Jim confirmed that while it makes sense that the accelerator pump is an unlikely place for a vacuum leak, it is part of an idle circuit that can jam up and be the source of a big leak, so best to just rebuild.
He also strongly encouraged me to rebuild my own carb instead of sending it in, largely because he said it's a fun job for a reasonably inclined person and he's at least 3 months backlogged
I had some time to tinker more today so I did a smoke test, again, and used a mirror to better see where it was leaking from. Hard to capture clearly with my iPhone, but with my own two eyes I can see that it is coming out of that plunger.
I just bought the truck. Seller did explain that he could no longer get it to drive past 45 mph without bogging and hesitating. And he didn’t wrench, so I knew what I was getting into.
Checked fuel delivery to the carb and all was good. I’ve had experience with a clogged cat, so pulled this one and saw it was toast. Seller refunded me $1200 for that (long story), so got that replaced.
Bought the smoke machine because really it’s one of the surest and easiest ways to check for exhaust and vac leaks.
Exhaust checked out fine. With the new CAT it drove better. I could drive past 45 mph! But there still was an occasional bog when accelerating and it was always right around 45 mph. Start-up and idle were always smooth.
Hooked up the smoke machine to the brake booster vac line, sealed off the air cleaner at the intake tube……
Now I know. No other leaks anywhere else, even with what looks like all original vacuum lines! All those will be replaced nonetheless while this carburetor is pulled.
I know I’ve read somewhere the plunger can be replaced without pulling the Carburator, but I’d rather not go that route. This isn’t a daily driver, and I’d prefer to do it all, and do it right, first go around.
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Nice smoke machine. They really do make it much easier to find these kinds of issues.
fjc-man
SILVER Star
Like too much advance too soon? Probably needs the advance weight stop pin repair.
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To be honest, no I am not sure. I have not gotten that far into her, yet. But it was next. I could smell the CAT burning so I started there. Honeycomb on one end was in pieces. Some looked like it melted, so “timing” was definitely suspect.
The plan was to go through everything anyway. And although it’s been awhile since I’ve tinkered with an carb, I assume that accelerator plunger weeping fuel and not passing my smoke test - is still one of many that should be dealt with nonetheless, correct?? Or is that not considered a potential vacuum leak?
Nonetheless, thank you for the question.
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…..will check this tomorrow. Read up on it here after you mentioned it. THANK YOU. I was not aware. First time 60 owner.
Learning something new about her everyday.
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I am thinking "No". It's up too high on the carb and I think that the plunger has to communicate with atmosphere for the plunger to be able to move up and down freely. I think that in order to check with smoke you would want to remove the carb from manifold, seal up the big hole left over and then pump the smoke in. You're looking mostly for leaks below the carb.
Setting your timing is a lot easier than taking the carb apart. "Bogging down" reminds me of what my engine does when the timing is too retarded. Most 2Fs (like mine) seem to prefer a bit more advance than 7*BTDC that the FSM calls for. Try advancing timing until the BB is just about to disappear from the window and see if the stumble gets better.
The rubber boot on the accelerator pump is installed from the top side. I suppose you can tease it out and install a new boot without removing much more than the accelerator pump lever. To replace the pump itself the air horn (top part of the carb) needs to be removed. It is held on by 8 screws I think. However, it's not that much more trouble to remove the entire carburetor assembly so you can work on the bench.
I just rebuilt two carburetors and neither of the accelerator pumps have a gas tight fit in the bore, at least when new. I suppose the pump seal may swell when wetted with gasoline. Looking at the carburetor schematic (lower picture), I think most of the smoke would enter the carb through the throttle bores. I'm not really sure how the smoke gets over to the plunger anyway, unless the carb is empty (no fuel in the float bowl. Anyway, good luck!
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Thank you, Sir.
You’re absolutely right. The more reading I’m doing the more I’m learning. Waiting on Amazon to deliver my new timing light today. It’s been over a decade since I last had a toy (no pun intended) to tinker with. Now that the kids are a little older and have more ME TIME, I brought this home.
I will definitely double check timing and the infamous dizzy pin. I have everything to do a full tune-up and valve adjustment so I sense I’m closing in on the issue.
Thank you, again. Will update when I’m done.
