exhaust leaks and backfiring

[stevo]

what shade tree method can be used to determine whether a mild exhaust leak is occuring at the joint between the muffler and heater boxes?
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When you cross an Irishman, they never forget. I mean, never.

[AndyM]

I've heard............that if ya stick a potato in your tail pipe............you can hear the gasses escape in a different location...........I heard...........sumpin like that.......maybe.

[JMazier]

[steponmebbbboom]

stuff a rag over the tailpipe(s) and feel for whooshing air from the joint with your hand. If backfiring is your symptom, I would be looking at your valve adjustment, and your idle mixture. In my experience, resealing the exhaust has never cured a backfire, only muffled it some.

[stevo]

i agree that its usually something in the ignition, and i have had the sputting with valves being off. this time [in the sunroof] the dwell is spot on and the timing perfect. then just to really fuck up the data i moved out the 30/31 and introduced the doka's 30pict2.

the 30pict2 performed adequately in the doublecab with an 034, not better as expected with the 035 dist in the sunroof. it wobbles at the lowest rpm's which annoys me. with the 30/2 idle in the sunroof lives at 950 but spikes to 1050-1100, or drops to the high 800's at idle. didn't seem that jumpy in the doublecab.

its hard to see myself going back to what are condisdered opposed carb/dist pairings. the 035 with its different vacuum scheme was to be the savior with either carb; but better so i thought with the 30/2.

nevertheless, the sputting was still noticeable once the engine warmed. both carbs were givien many test options so that there was little to no chance of running too lean or rich. it has to be an exhaust leak and i'll just have to go through it. i'll reswap carbs and retorque all the exaust nuts i can reach with new copper nuts - been meaning to use copper in the first place. my helper will be around soon to hold the rag while i investigate.
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When you cross an Irishman, they never forget. I mean, never.

[nemobuscaptain]

[steponmebbbboom]

[stevo]

yes, using that bosch plug,
the dist worked well enough with the 30/31,
and the bottom throtle shaft i reefed about a quarter turn.

still the same. since the bus is less responsive, and wanders so at idle i'm swapping things back and expect the sputs to continue regardless. on all todays test drives i found stalling at stops, most often downhill stops. the lack of response is something i had found in the doublecab and now see that its carburation. first gear with the 30/2 showed lame on both rides. not a worry - its early.

ray, no signs of carbon build yet. does have an unusually throaty to me sound at the tail pipe that i am not excited about. i had a bunch of carbon on the bumper before the re-ring. seems i put it back together better at that spot [damper to muffler], until i heard the sput backfires mentioned earlier.

EDIT: i was adjusting the carb wrongly. things have changed.

it's kooky to me: on the 30/2 one has to way out the one and only screw to maximum rpm and wind it down by using the idle set screw. going from fuel injection to more "complicated" carbs, to this its, well kooky. better for me is what it is. i've got much better idle at 850+/- 15-20rpm, and my test drive was sweet. the 30/2 worked fine on the doublecab, but its staying on the sunroof now. next, to mate the 30/31 with the 034. fweem.

2xed. backfiring all gone, cool runnings. who wants a potato...
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When you cross an Irishman, they never forget. I mean, never.

[steponmebbbboom]

so idle mixture cured it?

good to hear it, enjoy.

[IFBwax]

I have the same problem.. sticatto backfiring on decel... especially cold engine, going downhill... on my brown bus.

I have a friend who's a VW mechanic.. ran it by his shop today. He immediately thought exhaust leak. Stuffed a rag into the tail pipe with a 2 X 4 to hold it (it was hot!) and felt exhaust coming out of the area to the left of the muffler. Said a gasket or flange was missing. Said, it's a simple fix, 8 bolts. He actually moved the gasket a little bit that was in there and it's much better.. but of course no fix.
_________________
Owner of: "The Party Pickle" (a 1979 2 Liter FI "Raby Camper Special" Sage Green Westy Campmobile) & "Charlie Brown" (a 1979 2 Liter FI "Rob Grant Rebuild" Agate Brown/Dakota Beige Station Wagon)


www.partypickle.blogspot.com

[DurocShark]

Go to the 99c store.
Get a pack of playing cards.
Hold the card near suspected leak points.

You *will* feel the leak if it's there. Great for pinpointing which cylinder is leaking at the heads too.

Which reminds me, I need to do this next weekend on the Guac. Sounds like a split now!


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No boom today. Boom tomorrow. There's always a boom tomorrow.

[IFBwax]

I bet you use the joker card just for the heck of it.
_________________
Owner of: "The Party Pickle" (a 1979 2 Liter FI "Raby Camper Special" Sage Green Westy Campmobile) & "Charlie Brown" (a 1979 2 Liter FI "Rob Grant Rebuild" Agate Brown/Dakota Beige Station Wagon)


www.partypickle.blogspot.com

[DurocShark]

[IFBwax]

See what I mean???
_________________
Owner of: "The Party Pickle" (a 1979 2 Liter FI "Raby Camper Special" Sage Green Westy Campmobile) & "Charlie Brown" (a 1979 2 Liter FI "Rob Grant Rebuild" Agate Brown/Dakota Beige Station Wagon)


www.partypickle.blogspot.com