Chuffing problem

I've been struggling with a slight chuffing problem and am at the end of my rope. It sounds like the #1 cylinder and happens particularly at idle when the car is thoroughly warmed up.

I've checked the idle jets and they are all clear and clean. The idle was low, but I've increased it to about 900 rpm. That seemed to help a bit. I've also checked and re-checked the balance, and it appears to be spot on, but I'm going to give that another go this weekend.

I can't find any leaks at the carburetors or the exhaust manifolds, but I'm also going to try to find any leaks again this weekend.

Could timing be an issue? I have it at 30 degrees BTDC at 3000 rpm. Could a leak at the head cause chuffing? Maybe the head studs need to be tightened?

Any ideas on what I might be missing? What else could cause chuffing?

Had a head stud break causing problems, have a leakdown test done, it's a good place to start.

I don't want to upset you But I Had one do it with a cracked head. Its very uncommon And Im hoping Im wrong It would only do it when it was nice and hot,

A lose head will do it to and even a stripped case stud.

Before you go nuts pulling your engine out, try installing a new set of plug wires, disti cap and rotor. Might have a carbon trace in the cap near one lead, or a plug wire going bad.

Lots cheaper than pulling the engine.

If you have the room....Pull the valve cover on the suspect head...
Inspect the head studs visualy, then if you can get an open end wrench on them, try turning them...Any gap , or movement of the wrench will locate a loose or broken stud.(normaly)....

The studs under the tin ware are another problem.....

Hope this helps....

Leon C.

$0.02 worth: I recently had some running trouble develop in new system (~2K mi) traced to an overzealous fuel pump delivering too high pressure. Although I did not know about the high pressure and did not suspect that, as the parts are all new. But the pump was also leaking, so when I replaced it to stop the leak, the engine running trouble went away. Does "chuffing" = small backfires out the exhaust? If so, this is precisely what I was getting. FWIW.

I had black smoke and a hissing sound; traced it back to a leaking intake manifold gasket. Before you do anything else; change those, this time using a small amount of grease to seal them up. It might solve the problem and on the cheap.

My "chuffing" turned out to be a loose intake manifold. It had very litle "play, but replacing the gasket and tightening it up eliminated my "chuff". And it did wonders for my idle too. All thanks to my newly discovered VW guru.

Chuff is a great word - I had this instant recognition. Hope your chuf is as easy to solve as my chuff. Eliminate the chuff! Maybe somebody could start a knowledge thread and document associated sounds with problems and remedies. Grruanch - do this . . Kersnuffle - do that . . .

Thanks for the suggestions. I haven't had a chance to follow up on any of them because my wife suprised me with a trip to Mexico for my 40th birthday and we just got back. I did get a chance this morning to take a quick look and found one other thing I hadn't noticed until now. The gasket between the carburetor and the intack manifold look damp in a couple of places, like it is getting wet wtih fuel. Could that be a source for the chuffing? What would cause the gaskets to get wet? Floats set too high? Something else?

Start the engine and after it warms up, spray any area that is mated (carb to manifold, manifold to head) If the engine stumbles, then you have an intake leak. Also Spray around the spark plugs, go under the car and spray where the head meets the cylinder.

Great suggestion from Larry. Maybe you can just swap all four gaskets (intake manifold to carb and intake manifold to head) and follow the same procedures I suggested before, coating them all with a light dab of wheelbearing grease; you should be good to go after that.

Yeah...love that wheel bearing grease!

Larry didn't mention what to use to spray around your gaskets to find a leak. Some people use "Starting Fluid", sometimes called "Starting Ether" (which is what it is), but I think Larry and I both prefer to use plain old Carburetor cleaner. That seems to work just as well, and the Ether is sometimes hard to find these days.

gn

BTW: One of my Jack Russell Terriers "Chuffs".....He'll be sitting on the couch, looking out the window when a squirrel trots by. Then he'll perk up and sit there "Chuffing" - Chuff.....Chuff....not a bark, but sort of a stifled bark, until we let him out to chase those pesky buggers around the yard...

I have a big bottle of carb cleaner that I will put to good use! I also like the wheel bearing grease idea. I'll give that a try, too. I hope to get to it this weekend.

Let's see, spraying starting ether into a mainfold leak would make the engine speed up, but spraying carb cleaner into a leak would make the engine slow down - right?

Sometimes I chuff in public, but I try to pretend it was the other guy who chuffed, and not me . . .

David -

Whenever I 'chuff' - it usually clears the room!

David, yes, that's correct. I used to use ether for locating vacuum leaks but found that it was slow to react. Conversely, carb cleaner reacts very fast and you immediately notice when the engine stumbles.

I know I am about a month late getting into this thread, but is "chuffing" a sound or a feel. When I listen to my engine it sounds smooth, but when I give it the gas (usually in first or second gear) is when I feel it the most. It feels kind of like it's missing. Is that a "chuff"?

See? I told you guys we needed to start a Knowledge thread to define these sounds! Chuff, kerschnuffle, klinkty unk . . . .

Don't forget "boom shakalaka!"

How about: gaahk-cough-cough-hucka-hucka-galumph-splutter-wheeze? Which really does not do justice to what I just got through doing w/ my car. First time to fire it up w/ temps around 35. Not completely frozen, but colder than it's been in its life. It was really not wanting to go through with my desires. Coughing and spluttering and protesting vehemently. It did start, of course, and died a few times during the process. It likes lots of pumping of gas down its throat to get over the hump. In a minute or two things had settled down as they should. As to chuffing, my understanding is that this is a noise from the exhaust, at least this is how I have used the term. Sort of real mild backfires; a popping sort of sound. Also accompanied with a distinct odor of unburned fuel in said exhaust. All the splutter, etc. just mentioned is noise up from the carbs. The chuffing I was having a while back was at mild to feather throttle positions, and at idle, no load. When I stepped on it, there was a little hesitation then it got up and went like it should. Was very troubling for a time, but the fix was to realize that my fuel pump was over pressurizing the floats and so flooding the fuel delivery channels in the carb. This was most noticeable in the idle or low power circuit of the Webers, where they were running much too rich due to too much gas availble to them. The power circuit (main jets) seemed not much affected. Replaced the pump w/ one that works right, (3.5 to 4.0 psi) and my "chuffing" went away. FWIW.

Jack wrote: "is "chuffing" a sound or a feel. When I listen to my engine it sounds smooth, but when I give it the gas (usually in first or second gear) is when I feel it the most. It feels kind of like it's missing. Is that a "chuff"? "

Usually, it's a sound - a skight missing of the engine. If you begin to feel it, then there is definitely something out of adjustment.

If your engine is missing in 1'st or 2'nd, it could be a variety of things, but I would start checking in this order:

1. Give it a general tune-up:
- New points (set the dwell at 42-47 degrees if you have points)
- New distributor cap and rotor
- New Spark Plugs
- New Plug wires
- Adjust your timing (30 degrees at 3000 RPM if running a 009 distributor)
Test Drive

2. Check the stroke of the accelerator pump actuator for a bit more gas when the throttle is depressed. too little will cause a big hesitation when the accelerator is depressed, kind-of like a "Bog", then it takes off (but it doesn't "chuff!")

gn

I wonder if Rod ever solved his problem.

I could be wrong, but I think the "chuffing" Rod is talking about is coming from his carb(s). "Chuff" is a sound, that sounds exactly like: Chuff. If you are watching the carbs without the air filters on at the particular instant of a "chuff", you will notice a faint mist of fuel vapor puff up out of one cylinder's jets.

A chuff is not like a backfire throgh the carbs, which is more like a bang or pop. A chuff is softer sounding, like: chuff.

Don't ask me what causes it, but I know the sound. I'll get it 6
7 times for the first 15 - 30 seconds during rough idle after a cold start if I let the rpm drop below 1300/1700.

I have been curious what causes it as well. But since it seems to go away after warm-up, I've just passed it off as one of those cranky cold-start warm-up things. Maybe I shouldn't?

Mark

My Dells usually cough and puke so much during the first minute or so that I would never hear a "chuff" - honest!

It takes a whole lot of accelerator pumping to just keep everything alive, then, finally, it starts to smooth out and after 30 - 45 seconds or so you can actually back it out of the garage without stumbling...

There might be some information in Bob Tomlinson's books on tuning Webers and Dells about that vapour mist above the carb throats when cold. We know that the vapourized fuel condenses along the inside of the intake manifold runners when the engine is cold, so maybe something similar is happening up in the carbs themselves. Maybe someone could do a little research and let us know what's happening.

Ya know, one of the most agonizing parts of my entire (hot rod) VW life experience has all ways been the 1st start-up of the day in cold weather.
1st the starter screams out in real pain, then the popin', missin' and "chuffin" commence while my nervous eyes are glued to the oil pressure gage.
All the while my ears are straining to detect the next emerging high dollar problem as the cold parts clank against themselves.
Once the motor warms, I get well.
Isn't it great to love old and simple technology?

Yes Ernie...

Gordon, here's a simple fix for you.
Go into that fantastic living room of yours, eyeball that electric blanket on your loveseat ... and make a decision on who needs it more.
My guess is that Pearl would love it.
Poof! No more cold starts! :)

(Hey, wait a minute. You're keeping her in a garage in South Cackalackey! You shouldn't HAVE cold-start problems!)

Yeah, I tell people that I didn't need to add heater boxes 'cause I bought a house in the Warm South, instead. Heck of expensive alternative though, I'll admit!

I'm always amazed that I can go out to the garage on a warm Summer's day (like 90+ in Beaufort) and it just starts up...period. No coughing, puking or chuffing at all.

Still, even when it's down into the 30's (yes, I've driven it in the upper 30's) I just start by pumping the living hell out of it and THEN hit the starter and it starts right up, followed by even more pumping until, about 30 seconds later, it evens out and runs OK after that.

My wife's PT Cruiser has two zone electric heated seats. They really work great with leather (or vinyl). Wonder how compatable the mechanism and controls would be with speedster seats? I do know that they can get so warm it feels like you crapped in your pants - if that is of any help?

Warm crap......hmmmmmmm......

I understand that Henry installs electrically heated seats in some of his IM's, so I guess they're more than compatible.

Don't know about the warm crap, though......

It Depends . . .

BWAAA HAAA HAAAAA

Beat ya, Jim.

...DANG, you guys are raising the bar on this innuendo stuff!!

BTW - isn't an 'innuendo' an Italian suppository?

Just finished catching up on your input, both helpful and hilarious. The holidays intervened on my plans and I haven't had a chance to tinker with it. But, I have ordered new intake, exhaust and carb gaskets, and while I was at it a new billet Pertronix distributor that I should get next week. With luck I will be able to get to it next weekend. I'm hoping for a bad seal somewhere or a timing issue. Or, maybe a float problem. I really don't want to pull the motor.

I also have the CB Performance electric fuel pump, which got me to thinking about a possible problem with it.

The other issue I have is a slight fuel smell in my oil. There is no indication that the volume of fluid in the crankcase is changing, though. The dipstick level is staying exactly where it was the last time I changed the oil. Any thought on what that might be? Could it be related to the chuffing?

If the motor is fairly new maybe the rings haven't seated fully yet; and hence the smell. My guess is that if broken in correctly, the smell should go away as you keep using the motor.

If you can smell gas in the oil, you've got a leak somewhere.

If you don't have a stock, mechanical fuel pump mounted on top of the engine, then you've probably got a pilot valve leaking at a float somewhere. It leaks until the pressure runs out of the system, then stops, so you won't get a crankcase full of gas. If it's not a lot, too, then it may evaporate during running (no, it probably won't catch fire in there - where would it get an igniting spark?).

Still, get in there and find the leaking pilot valve.

I like Ricardo's idea better. Sounds like less work. But, I have a hunch Gordon's onto something. I just got my new Pertronix Billet distributor (Merry Christmas to me!), so since I'm going to be tearing into things a little anyway, I may as well tear into it all. I ordered new gaskets (carb and exhaust) and will be pulling things apart, checking for leaks and replacing all the potential culprits between now and next Sunday. Keep your fingers crossed.

I consulted a freind on this and he said a cheap dizzy or a bad cap and rotor.

So we agree with Gordan..

But cheap dizzys can be tweeked in to spec. if your good with a timming light and a Gm dizzy spring asortment making your own custom dwell curb I prefer 10 degrees before TDC at idle and 30 degrees at advance at 3,000 rpms. 28 is closer to stock. But try it and see if it helps and improves your milage. its not that hard to change back.So take note of which spring was where. and tag them when removed.

Your New dizzy may already set that was Id try it first and see wat you get And it wouldnt hurt to get some new gasket for the intakes and carbs. Just incase Im wrong

Just taking a break from working on it. I installed the new dizzy yesterday. Need some help on one thing, though. I need to verify that the orange wire on a Vintage Speedster goes to the negative on the coil. I can't find my wiring diagrams. I made a "mental note" when I started the project but am now suffering from self-doubt and want to be certain before I power it up.

I'm also taking everything apart and setting float levels and replacing all the gaskets from the carbs down to the intake manifold, adding just a bit of wheel bearing grease to the gaskets, as someone suggested in the past.

I'm also changing my main jets from 150 to 145. I'm still running rich and had 150s.