Okay,
So ive got a stock 1.6 in my bug and anaftermarket exhaust. Ever since ive put the exhaust on its been knocking on the car when i start it and turn it off but its onlt just a bit.
But a few times before i got the exhause i would tun it off and it would shut the engine down but then it sounded like it was trying to start and shakes around alot like moves the car its so violent but it only lasts 5 seconds at max.
It doesnt do it often but it does it enough to make me wanna stop it.
It eems like its shutting down just as its coming up on the compression strock on a cylinder and it seems like it just starts to come back from that and rocks back and forth.
DOes anyone have any ideas?
Cheers Josh
It sounds like Pre-Ignition; this is where a buildup of carbon in the expansion chamber retains enough heat to make the motor Diesel even when there is no ignition. To fix it would mean removing the heads and cleaning the crap out of them.
There may be some WONDER FLUSH chemical that when mixed with the fuel cleans it for you but I wouldn’t know.
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Check the timing of the dizzy, if it is too far advanced it will run on.
If it is coking then it is easily removed by squirting water in the carb when the engine is running (use a spray bottle)
But I would bet it is too advanced
Keeping it real !
okay. would this have anythin to do with my dizzy not holding vacuum
probably as the dizzy is advanced by vacuum, but not so much at low or idle revs Where is it leaking.
Keeping it real !
it just doesnt. preety certain its the bit on the side of the dizzy
can you swap dizzys or get a mechanical advance one?
Keeping it real !
not right now i could get one from a 64. but it doesnt do it often
The running on or dieseling can damage your engine badly if allowed to persist, I've seen broken crankshafts from this occuring. It's caused by too much heat/compression and or tune up. It's best to keep the car in gear and slide the clutch a little to allow a little clutch drag to slow and stop the engine if there's any chance of it happening. The dissy could certainly be part or all of the cause. Get the timing and advance curve checked.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
Okay. So how woUld i get That checked?
With a timing light
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
Okay. The only issue with this is That it doesnt happen often enough for me to tell if its stopped doing it. It may only happen once every seven or eight weeks and sometimes not for four or five months.
Check the ignition timing and with a good timing light proove the advance is operational and to 30* full advance. Carb needs to be adjusted corectly too.
The running on problem is caused by too much combustion chamber temperature, which is caused by carbon build up, or too advanced ignition timing, or carby running lean, or too high compression ratio, or too low fuel octane, or cooling system faulty, or quite a few other things, or a combination of any or all of these, but you get the idea.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
One other thing to check is the solenoid (Fuel cut off) at the base of the carby. Check the lead is connected and powered. Sometimes if this solenoid is not connected or working properly the you can get dieseling.
71-BEETLE-SEDAN wrote:okay. would this have anythin to do with my dizzy not holding vacuum
Could the leak be causing it to run too lean? Plug the vacuum hose and see if it helps.
Make sure you are using good quality fuel. My '63 bug will do exactly what you are describing if it is run on anything less than premium unleaded.
I only use standard unleaded (ULP) for washing parts (in emergencies) and starting fires. I even run premium in my lawnmower! 😀
R 🙂
40hp, 6V and ...er... slowly making improvements
😂
It's nice to be important, but it's more important to be nice!
Founding member of the Gold Coast Dub Club Inc. 🙂mine over runs because my idle is a bit high.
as well as the engine runs a bit hot in this weather
and the slight more compression ratio yada yada
even with idle cut off it still over runs a bit
too much advance does heat the engine up a bit but when you turn off the key there's no more spark
maybe when you change the exhaust it idles higher mine did that
my speculation is engine is running a bit hot from weather?
idle speed, idle mixture
basically get it tune up
if symptom persists it's probably inside the head carbon build up
or the heat sinks is clogged with oil, dirt and grease and air can't flow very well
ratty 63 wrote:...I even run premium in my lawnmower! 😀
R 🙂
haha me too.
yeah just turn the idle down.🤪
😂🤪😂🤪😂
car forums. where a lot of peoples good intentions end up taking a good old car off the road forever never ever to see the road again. 🥲
