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 Pat
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 posted on September 1st, 2003 at 01:31 PM |
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backfiring problem
I've been having a lot of trouble getting my new engine to run properly. Could anyone give me some pointers?
The Symptoms:
It idles really smoothly, but as soon as you accellerate it hesitates badly then usually backfires, sometimes a slight pop through carb, other times a
loud bang out the exhaust.
The Motor:
1600 twin port, kadrons, 009, extractors.
Now, I have tried:
Timing, static and at full advance, using the metod described on Aussiebug's page
Fuel filter replaced
Checked all intake and Exhaust manifolds for leaks
Points cleaned and gap set.
Pulling my hair out, swearing etc.
None of this has made any difference.
Any ideas? |
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oval TOFU
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| posted on September 1st, 2003 at 01:50 PM |
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hahahahahaha
no really.. this is what was/is (coz i aint go no time to have a proper look yet!) happening to my engine too.... sounds like its exactly the same
symptoms - nice idle, then flat spot with backfiring and poping outta da carby....heres a thread that we made earlier on in the show....
http://www.aussieveedubbers.com/forum/viewthread.php?tid=8899
:beer
PS: my car wont even start now so i cant fix up the old problem of a coughing and farting engine... so the joke's on me i suppose....
good luck dude (try yelling and swearing louder with four letter words starting with C and F.... and maybe a mix of the two and others like S&^%
and B^&%###$% @$$ ^&*)( and such....
[Edited on 1-9-2003 by oval TOFU]
[Edited on 1-9-2003 by oval TOFU]
[Edited on 1-9-2003 by oval TOFU]
...and Robert's ya father's brother...
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 Bizarre
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| posted on September 1st, 2003 at 01:51 PM |
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Have you set the linkage up properly??
Are the carbs sync'd???
If it is back firing then it is rich??
Do you know what jets you have in there??
Have you had a look at the AJ Sims aka Mr Kadron ( http://www.lowbugget.com ) trouble
shooting page.
Coil, points, leads are all good???
I had a dud coil that was fine on a 1776 with a progressive but when i went duals it broke down and did all sorts of funny things.
If you have the right-ish jets in there and all vacuum leaks have been excluded i would have to look at linkage/sync'ing the carbs
How did you balance them???
Are you running a balance line???
Futue te ipsum!!!
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Pat
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| posted on September 1st, 2003 at 02:10 PM |
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I haven't touched the carbs, this is a second hand motor I recenty bought and installed, which was running ok, so I haven't played with the
carbs yet. (I will tune them usin AJ simms guide, but how the hell do I get to the mixture screw wwihout pulling the carbs out?, there is SFA room)
Points and leads are all OK, how do I test the coil?
The carbs are runing a balance pipe.
Ooh, suits you sir!
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Bizarre
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| posted on September 1st, 2003 at 02:26 PM |
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| Quote: | Originally
posted by Pat
I but how the hell do I get to the mixture screw wwihout pulling the carbs out?, there is SFA room)
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ahhhh the joys of duals 
Sorry no idea.
I run IDF's and drilled some holes in the side and access is actually a breeze.
If it came of a "running" (it WAS running good?) then i would bet pounds to a poo that it is a linkage problem.
They only have to be opening one side more than the other and they will run crap.
How did you balance them??
Do you have a syncrometer?? or did you do it by ear or pretend that cause you didne touch them they wont have moved in the remove and replace
episode.
Mixture screws - well yes. If the were jetted right before you shouldnt have to touch them. But i would to "know" they are right.
You WILL have to remove the linkage and balance the carbs. Then replace the linkage so as the is NO effect on balance. I have only touched Kads one
and i have to admit give me a Redline Hex bar anyday.
Persist - you will enjoy the rewards
an after thought. How rough were the Kads treated in the removal??
Could a float be stuck or something???
Futue te ipsum!!!
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Pat
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| posted on September 1st, 2003 at 02:52 PM |
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[How did you balance them??
Do you have a syncrometer?? or did you do it by ear or pretend that cause you didne touch them they wont have moved in the remove and replace
episode.]
The latter.
This is the first time I've touched a dual carb vw motor, so I guess I've got a lot to learn.
I'll have a look at the linkage.
I don't mind paying a vw workshop for a proper tune, (especially after seeing the amount of space you've got) I just want to get it
driveable, so I don't have to tow it there.
Ooh, suits you sir!
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Bizarre
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| posted on September 1st, 2003 at 03:08 PM |
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| Quote: | Originally
posted by Pat
This is the first time I've touched a dual carb vw motor, so I guess I've got a lot to learn.
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About 18mths ago i was sitting there and my motor was back firing to hell. :cry :cry :cry :cry :cry
Yep - twins are a different hand ful to singles.
If it is new to you do your self a favour and go to a carb shop and by your self a syncrometer with the meter. DONT BUY THE MOVING BALL TYPE.
After you have done it a few times you might be able to go with out the meter but it is easier with.
Also buy a packet of Pringles chips. Any flavour. The diameter is perfect for fitting over the filter bracket so as you can do a reading. You need to
cut the packet down but it is longer than the small packet. Buy the big one.
Also go to http://www.aircooled.net and read the tech articles there. Some good
advice there as well
Futue te ipsum!!!
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Pat
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| posted on September 1st, 2003 at 06:37 PM |
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OK so I played around with the linkage a bit, adjusted it taking measurement to ensure both carbs were opening the same amount. I found it had been
bent a slight amount, so I straightened it.
Now it runs worse.:cry
I think the linkage is not the problem.
I might pull the carbs apart and rebuild them. But in the meantime I really need to get my car running. I might just chuck a stock single carb on it
for a while, and take my time getting the kads done properly.
Ooh, suits you sir!
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Bizarre
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| posted on September 1st, 2003 at 07:07 PM |
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Well-- in a way Pat , that is good
I reckon it points to your linkage being the problem.
Yes it takes a while but IF you need transport quickly throwing a stock on there is a good idea.
You HAVE to get that linkage near PERFECT or it will behave like a pig. Unfortuneately the base kad linkage is its week point.
Kads have a push pull operation unlike IDF's or DRLAs cause a Kad is both LH (or RH ) operation where as the others are left and right.
There are some good articles on http://www.aircooled.net (did i mention that?)
Futue te ipsum!!!
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FirstName V LastName W
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| posted on September 2nd, 2003 at 01:01 AM |
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If an engine idles smooth and starts easy then the balance is pretty close to the mark. Even the idle mixture has to be very close to the mark if it
idles smooth, as you have said. A carby has what is called an accelerator plunger which gives the engine a shot of fuel to get it up off the idle
circuit into the main circuit or onto the main jet if you like. On the kadron there is an adjustment for this plunger no different to any other carby.
I would be looking at increasing the amount of stroke on the plunger as it sounds like the engine needs more fuel. The other test you can do to
satisfy this theory is to try and rev the engine up slowly if it does this without backfiring and hesitating then the problem is as I suggested if not
well GOOD LUCK. 
Each to their own just remember what goes around come around.
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Herbie
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| posted on September 2nd, 2003 at 01:51 AM |
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I'm not convinced its a carby problem,
Do you know or trust the distributor?
Are you running a vacuum advance?
if yes is it getting the right message to the dizzy?
As soon as you crack open the throttle you lose manifold vacuum and then the advance jumps toward retard
If you are not running a vacuum line and the dizzy is not set up properly it might explain the sudden death and carry on with the back fire.
I would try the stock carby too to eliminate possibilities.
I have had carby troubles similar to what you are talking about but that was the wrong emulsion tubes as the carby was setup for a different type of
motor.
I hope some of this helps.
Cheers Tony
62 Ragtop Herbie with a little extra oomph.
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Pat
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| posted on September 2nd, 2003 at 11:00 AM |
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It has a 009 on it, which is centrifugal advance.
Ooh, suits you sir!
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Herbie
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| posted on September 2nd, 2003 at 01:29 PM |
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I think most Dizzys are centrifugal but does the 009 dictate that its centrifugal only and has no vacuum facility?
62 Ragtop Herbie with a little extra oomph.
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Bizarre
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| posted on September 2nd, 2003 at 01:58 PM |
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009 is centrifugal only
Futue te ipsum!!!
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Herbie
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| posted on September 2nd, 2003 at 09:57 PM |
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hmmmmmmmmmm
OK, well maybe its not the vacuum advance then
I supose you can try the carb swap and if that cures it then copy the setup of someone running similar specs and then play from there.
I'm probably not telling you anything new, Sorry.
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62 Ragtop Herbie with a little extra oomph.
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Grey 57
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| posted on September 3rd, 2003 at 08:58 PM |
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I'd be looking at the electrics. Is the mechanical advance operating properly (freely returns when turned by hand) Is the dwell set correctly.
Points gap is one thing but correct dwell is more important.
Be chucking on a new coil to be sure.
I find with my 009 the flat spot gets worse with a richer idle mixture setting.
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Pat
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| posted on September 4th, 2003 at 06:53 PM |
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Yup it was the coil. Thanks everyone for your help.
Damn this engine goes a hell of a lot better than the old 36 horse. I just have to fix a minor (hopefully) oil leak, and I'm back on the
road.:thumb
Ooh, suits you sir!
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bugboymatt
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| posted on September 4th, 2003 at 07:12 PM |
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Glad ya got it sorted out mate.
Hate niggly little things like that always gives ya the shites.......
Da Time For The Aircooled Revolution Is Upon US.
Brothers & Sisters Lets Hit The Streets, Roll As One. And Feel The Power Of The Aircooled Storm.
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Bizarre
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| posted on September 4th, 2003 at 07:18 PM |
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I think that is proof in my books that the first thing you do when putting on duals is to change the coil!
Seems to cause no end of un-findable troubles
For $40 it is well worth the money
Do you have the Kads on??
or did you revert to a Pict.
GLAD you got if fixed!!
:bounce:bounce:bounce:bounce:bounce:bounce
Futue te ipsum!!!
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bugboymatt
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| posted on September 4th, 2003 at 07:25 PM |
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Dodgy coils. i think mine is on it's way out. just need to decide which one to buy next !!!!!!
Da Time For The Aircooled Revolution Is Upon US.
Brothers & Sisters Lets Hit The Streets, Roll As One. And Feel The Power Of The Aircooled Storm.
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Bizarre
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| posted on September 4th, 2003 at 07:33 PM |
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I will jump in and say - no decision
Bosch Black
Futue te ipsum!!!
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bugboymatt
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| posted on September 4th, 2003 at 07:35 PM |
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Ok cool. any part number for that or simple as going into store and asking them for a bosch black coil !!! umm carn't be that easy ??????
Da Time For The Aircooled Revolution Is Upon US.
Brothers & Sisters Lets Hit The Streets, Roll As One. And Feel The Power Of The Aircooled Storm.
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Bizarre
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| posted on September 4th, 2003 at 07:47 PM |
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Bosch SU12
It has a higher resistance i believe than the Blue coil and is suited to electronic ignition and points
Blue is suited to points
Futue te ipsum!!!
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bugboymatt
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| posted on September 4th, 2003 at 07:51 PM |
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Cheers blue.
I running petronix. and an old gt40 which looks like it came from the ark.
will call in and pick me up a new one i thinks.............
Da Time For The Aircooled Revolution Is Upon US.
Brothers & Sisters Lets Hit The Streets, Roll As One. And Feel The Power Of The Aircooled Storm.
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bugboymatt
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| posted on September 4th, 2003 at 08:44 PM |
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just checking out the bosch website !
it say su12 for standard then gt40 for super sports and gt40t for transformer type !!
MORE confusion !!!!!!
Da Time For The Aircooled Revolution Is Upon US.
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Pat
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| posted on September 4th, 2003 at 08:57 PM |
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Still have the Kads, damn glad I didn't swap them for a pict now
I still need to get them properly tuned though.
I put a gt40 coil on it, is there any reason I should have gone with the standard black/blue coil?
Once again thanks for all your help.
Ooh, suits you sir!
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Bizarre
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| posted on September 4th, 2003 at 09:08 PM |
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One of the big cans or the little ones??
I just believe that the Bosch is better. I have had friends who have had the GT's (little) go funny early.
There was a few other discussions earlier about this.
If it is working now just keep an eye on it.
Are you running points or electronic?
Electronis need a coil with at least 3 ohms resitance. Other standard points type measure 1 ohm. This causes the electronic modules to burn out
early.
HAPPR CRUIZING WITH NEW DONK DUDE!
Futue te ipsum!!!
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Pat
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| posted on September 4th, 2003 at 09:17 PM |
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Bring on the next Melbourne dyno day
I should beat my measly 20hp reading from the last one.
Blue, it's the big can type, same size as the stock one. I'm running points.
Ooh, suits you sir!
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Grey 57
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| posted on September 4th, 2003 at 11:07 PM |
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Woo hoo Pat, busting the 20hp barrier eh. The dyno master. Might have to get serious too then.
:thumb
Glad it all worked out for you mate.
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Pat
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| posted on September 5th, 2003 at 02:22 PM |
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It's all good except for a weird oil leak, but I think I've got that sussed out now.
Next upgrade: Brakes:o
Ooh, suits you sir!
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