Outer Limits 4x4 Board

After some info on modifying a air-cleaner box fitted with a snorkle to stop back-firing.............

For the moment i have turned the snorkle head facing backwards ,this has done the job for the - short term...............

So any ideas ?

Cheers

i'm guessing turning the snorkel head helped because its on gas... ?
more info champ.
but a good tune n service to stop the backfiring issue might be in order...?

Yes only on gas

new kit just fitted and runs great, but gas systems don't like snorkles when ram feeding air . thats why i turned the head around, thats why u need to mod the air box.............but i don't know how............

angry wrote: but gas systems don't like snorkles when ram feeding air . thats why i turned the head around, thats why u need to mod the air box.............but i don't know how............

coughbullshytecough cough

The backfiring is due to pi$$ poor tune, LPG systems require a much further "spark advance" than a petrol motor does ........
If your running for example 6degrees firing BTDC (Before Top Dead Centre ) then crank the dizzy around to 16degrees BTDC as a starting point & adjust from there to suit the LPG side of things

I have a 253 V8 here that wont run well on LPG untill the timing is set at 29degrees BTDC

yet on petrol it loves it at around 10degrees BTDC .... go figure
( and before all the drips under pressure respond .... yes it has had the timing set with a timing wheel and has a new harmonic balancer fitted aswell....... neither are lying although the harmonic is 2degrees out )


Kingy

fit a balance tube if u can that should fix it
advance factory + 2 degrees

V8Patrol wrote:

angry wrote: but gas systems don't like snorkles when ram feeding air . thats why i turned the head around, thats why u need to mod the air box.............but i don't know how............

coughbullshytecough cough

The backfiring is due to pi$$ poor tune, LPG systems require a much further "spark advance" than a petrol motor does ........
If your running for example 6degrees firing BTDC (Before Top Dead Centre ) then crank the dizzy around to 16degrees BTDC as a starting point & adjust from there to suit the LPG side of things

I have a 253 V8 here that wont run well on LPG untill the timing is set at 29degrees BTDC

yet on petrol it loves it at around 10degrees BTDC .... go figure
( and before all the drips under pressure respond .... yes it has had the timing set with a timing wheel and has a new harmonic balancer fitted aswell....... neither are lying although the harmonic is 2degrees out )


Kingy

its actually not bullshit

if you dont have the balance tube, you shoudl not pressureise the airbox on a LPG fitted vehicle.

Jes

I run around 16 deg advance on my gq!!

ratboy wrote:fit a balance tube if u can that should fix it
advance factory + 2 degrees

Fitted the balance pipe and all GOOD

Cheers for the info

Fit a balance pipe.

When you ram the air into the intake system there is more pressure at the mixer venturi than there is on the secondary diaphragm in the converter which is only exposed to bonnet pressure (very close to atmospheric).

Fords and holdens had the same drama with LPG when they started to fit their cold air induction ducts. They ran a pipe from the atmo port on their vialle converters to the airbox and it solved the lean out problems at high speed.

Balance pipe, and then it wouldn't hurt to give it a tune as well.

just finsh fixing a mates car. same problem.
we used a hole saw and cut 2 40mm in the intake pipe between the carbie and the air box. then you stretch a wet suit tube over the holes.
the sucktion will keep the water out and it will expand when it back fires.

I fitteda balance tube to my 100 series on gas and its all good,

Back firingis either dodgey spart plugs , leads or a tuning problem.

After i blew the shit out of my air box , i got it re-tuned and its as good as gold know.

So what sort of range do ya get out of ya 100 series on LPG

i get about 370 ks ffrom 90ltrs around town

Plugs and leads. Anytime I have had backfiring (esp on a Series 1 Disco) new plugs and leads fixed the problem.

also running lean