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Backfiring out the carbie

Started by Heath , Mar 03 2006 05:05 PM

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15 replies to this topic

#1 Heath

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Posted 03 March 2006 - 05:05 PM

Hey all, the car's been sitting out there for the last six months with different things coming in and out of it, and it hasn't run well since.

Anyway, putting fuel etc in it now, i'm gonna try and get the damn thing running tomorrow morning with some mates around, but I'd like to tackle it with a few possible solutions in my head. Rick said the needle in the carbie may be stuck, and it is backfiring out of the carbie... it really doesn't like it when we pour petrol down there, it will either crank over a few times and then die in the arse, or do the same and backfire in the pourer's face.

Why is it backfiring out of the carbie? Any typical reasons for it to do so?

I've got a whole spare engine here now, so I should be able to prime the lines one way or another, and we're gonna rekit the carbie tomorrow as well if all goes to plan. Any things to remember or try?

Even if it's running like shit, I'm still happy. As far as I know it's not a timing problem coz none of the timing has been touched really. Thanks in advance

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#2 _MYLJ_

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Posted 03 March 2006 - 05:14 PM

backfiring out of the carb sounds like firing order may be wrong. Have you had any plug leads off? Or it could be a lean out back fire , but I doubt it, or the lifters have bled down and it is not operating the valves properly as the lifters need oil pressure to pump back up sometimes , particularly if its been sitting a while. Or something nasty like a bent valve will cause a backfire throught the carb

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#3 _rorym_

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Posted 03 March 2006 - 05:19 PM

Was the dizzy off?..Might be a tooth out.
R

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#4 Heath

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Posted 03 March 2006 - 05:45 PM

All the plug leads have come off and on, so has the dizzy. I've checked it over and over with the firing order though (thankfully it's written on the manifold, now I've even memories it looking at it so much. 153624)

I hope it's not a bent valve, but your 186 head is gonna go on there soon anyway. Tell me about that "Lean out backfire" because that sounds like what may be happening. Trying to get the fuel pump working at the moment.

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#5 _Yella SLuR_

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Posted 03 March 2006 - 06:09 PM

Timing set to TDC intake stroke rather than TDC power stroke. Pop the side cover off front inspection cover and make sure that both valves are closed for cylinder 1, both tappets down, TDC power. Reset timing.

Edited by Yella SLuR, 03 March 2006 - 06:11 PM.

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#6 _MYLJ_

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Posted 03 March 2006 - 06:15 PM

If you have had the dissy out it is very likely that it has gone back in a tooth or two out. Did the dissy go back in with the rotor button(not the diisy housing) pointing in the same position as when it came out? or did you turn the motor over with the dissy out ?

Lean backfire would take me all night to explain fully (and then I'd probably be wrong anyway :rolleyes:

) but I've had a holden six that would start and Idle but when you opened the throttle up the motor popped and stopped, the main jets were blocked and it was leaning out as it came off the idle curciut as it gets more air as the butterfly opens, thus leaning out. If you have been poring fuel down its throut and it pops its not lean (rich maybe

but not lean)

I have also suffered a lean out backfire when doing burnouts at high rpm, not a good idea to run out of fuel suddenlyat 8800rpm :tease:

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#7 _Loki_

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Posted 03 March 2006 - 06:21 PM

Old rag off/on/off/on over the air-intake to pull fuel through the lines trick instead?

I'd get the fuel sorted out, pump working lines primed properly before trying to work out why it isn't running properly when it's fuel delivery method is a can down it's throat

Edited by Loki, 03 March 2006 - 06:23 PM.

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#8 _rorym_

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Posted 03 March 2006 - 06:30 PM

Listen to Yella...Listen to Yella..
R

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#9 _Jewboy_

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Posted 03 March 2006 - 10:05 PM

Yeah its common to backfire through the carby especially if you have moved the dissy. First thing to check is that the dissy is in the right spot. Turn engine to TDC on #1 and rotor should be pointing to the #1 lead on the cap, turn dissy to suit. If its out and you can't get enough turn then you need to pull the dissy, and turn it a touch more clockwise than the required position as the rotor will turn back as it drops down). As Loki said a good way to get fuel into the carb after sitting for awhile is to crank the engine while holding a rag on top this actually sucks fuel up into the carby even if your pump is stuffed. If fuel has drained back its most likely due to a cracked hose, the ones at the tank are the the usual suspects as you hardly ever look at them. If the engine still doesn't start try turning the dissy slowy while cranking until it fires.

I forgot to mention that be sure the dissy is on the right stroke by checking that the points are starting to open when your at #1. You can get a car to run if its 180 degrees out but it runs like crap (i've bought 2 cars from people who have done this and is why they get rid of them) which might explain most of your probs.

Edited by Jewboy, 03 March 2006 - 10:14 PM.

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#10 rodomo

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Posted 03 March 2006 - 10:52 PM

"Pop the side cover off front inspection cover and make sure that both valves are closed for cylinder 1, both tappets down, "

Easier and quicker to take off oil cap. Valve forward of oil cap is No1 inlet. Rotate engine in direction of rotation. Watch this valve open and close and the next time the timing mark lines up is No1 compression.

RACV MAN

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#11 Heath

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Posted 04 March 2006 - 07:50 AM

Okay I should be able to manage that. Thanks for that info Jewboy, I just pulled off a tank so now I sorta know what I'm doing back there, and I've got a few hoses left over lol, none of which are fantastic but they don't have holes at least.

I'll stick the other fuel pump in and replace the filter-pump hose because it's fractured, hopefully that will get me somewhere before Stewart rocks up.

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#12 _rorym_

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Posted 04 March 2006 - 08:33 AM

My stepsons HG was doing the same thing and when I looked the dizzy was a tooth out...now it starts from cold first hit,,,still runs crap with the twin wrong sized strommies but I have a single coming to get that fixed.
R

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#13 Heath

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Name:Heath
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Posted 04 March 2006 - 12:59 PM

Well we just got the beast running again. Fark that is a relief. It's a bit of a pain not being able to turn the headlights off and disengage the handbrake, and it's running like crap for now, but I am bloody pleased.

We rebuild the Stromberg, I stuck a different fuel pump on there and cranked it over for yonks, but it got there in the end.

Ahhh man, so stoked. Thanks for all the advice, and the backfiring was just a lean-out thing. Once the fuel is pumping through there it runs, but I still need to fix a fuel pump leak :( and find a battery that has some life.