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What's going on after spark plug change?

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kinga
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What's going on after spark plug change?

Post by kinga » 24th March 2019 - 4:17pm

Hi all.
Just replaced the spark plugs on my fastback.. got the scratched knuckles & wrists to prove it!
Also changed the oil in my air filter.
Used it to work a couple of times and it drives sweet but has been ticking over a bit lumpy.
Took it for a drive today and it's backfiring a bit under load.
Also, it is fitted with a co meter that has now maxed out at 22.5..usually shows about 12 on tickover and 15 when pulling.
The air filter housing was a bit tight to get out & I know I knocked it against so.ething when I pulled if out.
Anyideas folks?

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broady_6
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Re: What's going on after spark plug change?

Post by broady_6 » 24th March 2019 - 4:50pm

12 co at idle is waaaaaay over the limit. 2-3% is what you should be aiming for. Or is it an afr gauge you've got fitted?

Have you knocked the balance pipe off? It could be that the ht lead was tired and when you removed it its broken inside so you're getting bad or intermittent spark.

That or you've turned the mixture screw on the carbs reaching the back plugs, that's very easy to do.
The sultan of swing

kinga
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Re: What's going on after spark plug change?

Post by kinga » 24th March 2019 - 9:50pm

Yes..it's an afr gauge.
So, maybe worth trying new ht leads.
Where is the balance pipe?
Appreciate the help.
Think it must be something basic as it has always run like a Swiss watch!

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broady_6
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Re: What's going on after spark plug change?

Post by broady_6 » 24th March 2019 - 9:59pm

Ah well as its an afr gauge it makes more sense. If its gone if the top of the scale then its gone very lean. So you've created an air leak or wound the needles in. Now I'm assuming you have got twin carbs, if that's the case o n the bottom of each manifold is two stubs (one stub for single port 1500) which connected to a pipe which goes around the front of the engine to the other carb. It's all joined up with rubber hose its not in common for that hose to get tired, and the smallest disturbance can knock it off.

I've drunk a fair bit of whisky so if that's all jibberish, you know why
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purplepeter
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Re: What's going on after spark plug change?

Post by purplepeter » 24th March 2019 - 10:07pm


kinga
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Re: What's going on after spark plug change?

Post by kinga » 25th March 2019 - 12:11pm

Many thanks for the info guys..the car has oem carbs so I will check the pipes and report back.

kinga
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Re: What's going on after spark plug change?

Post by kinga » 25th March 2019 - 6:37pm

Ok..just had a play after work..
All of the pipework looks fine..
But..I now remember that I messed around with the 2 little metal tabs on the rods that actuate the flaps on the tube that comes from the air filter towards the rear of the car.
Apologies..hope this is making sense but not really sure what the bits are called.
There is a metal tab that was previously wedged in place against the edge of the housing..I pulled this out of position so the little weight is free to move up and down.
There is also another tab more towards the rear of the car..this can slot into a little notch..I moved this out of the notch.
This appeared to close off both of the flaps so air couldn't get into the air filter and the car must have been choking up.
I have now returned these little tabs to how they were and all seems ok.
It seems that the flaps now allow air into the air filter
Like I say, hope all this makes sense. I took a photo on my phone but not sure if/how I can get this onto the thread.
What is the purpose of the tabs that work the flaps?
Tnx again folks.

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broady_6
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Re: What's going on after spark plug change?

Post by broady_6 » 25th March 2019 - 7:09pm

At the top of every section is a photo posting guide.

viewtopic.php?f=26&t=14260

Im not sure what you mean by tabs. Theres a weight on the air filter intake which works in opposition to the suction of the engine. And the other flat is connected to a little thermostat and changes the airflow from the warm air pick up to the cool air from the rear valance.

I cant see your theory being correct, as starving your engine of air till cause the AFR number to decrease. To get an AFR number to be bigger you need to add loads of air or reduce the amount of fuel. Where is the lambda sensor for the gauge?

I suspect it may be the opposite, and the two flaps have been wedged shut. Freeing them off opened them up. It sounds like your engine needs a good tune up with a gas analyzer to be honest. Something must be wrong if someone felt the need to starve it of air by blocking parts of the air intake.
The sultan of swing

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broady_6
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Re: What's going on after spark plug change?

Post by broady_6 » 25th March 2019 - 7:14pm

Little bit of info on airfilter set up here

viewtopic.php?f=26&t=14390
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kinga
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Re: What's going on after spark plug change?

Post by kinga » 26th March 2019 - 8:45am

The tans o am talking about are on the end of the metal rods that are fixed to the flaps.
Probably not explaining myself very well!
Before I changed the plugs the tabs were wedged such that both of the flaps were open, and there was clear air flow from the rear valance into the air filter..I have now returned these to the same position and drives perfectly again.
So, what do the flaps do..with the weight free to flop about, the weight if the weight pulls the flap closed with the engine off..does this flap get opened when the engine is Running, to allow air to flow onto the air filter?
What is the purpose of the other flap (the one closest to the rear valance)? You seem to be able to lock this so the flap stops air coming from the engine compartment but draws air from the red valance?
Thanks again for the info guys..very much appreciated.

kinga
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Re: What's going on after spark plug change?

Post by kinga » 26th March 2019 - 8:47am

Can I post a picture directly from my smart phone here..had a go last night but couldn't sus it out.

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broady_6
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Re: What's going on after spark plug change?

Post by broady_6 » 26th March 2019 - 10:23am

No you can't post directly to the forum, we don't have the webspace. You have to upload it to a 3rd site first and copy the link across.
The sultan of swing

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Editor
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Re: What's going on after spark plug change?

Post by Editor » 6th April 2019 - 1:46am

You probably interfered with the warm air inlet to the air cleaner. Those flaps automatically allow an amount of warm air into the air intake and carbs. The notch can be set to stop the heated air in if the engine is running in a warm/hot country.
Dave.

kinga
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Re: What's going on after spark plug change?

Post by kinga » 8th April 2019 - 9:09pm

Thanks guys - all sorted now.

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broady_6
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Re: What's going on after spark plug change?

Post by broady_6 » 8th April 2019 - 9:33pm

kinga wrote:
8th April 2019 - 9:09pm
Thanks guys - all sorted now.
You can't just say that!? What was it? it may help someone else in future too :D
The sultan of swing

kinga
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Re: What's going on after spark plug change?

Post by kinga » 9th April 2019 - 8:40am

Looks like both of the flaps were wedged before I messed around with them such that the flap with the weight on was wedged open and the flap that diverts air from either the engine compartment or the rest valance was wedged on the little slot, so air us coming from the rear valance.
Hope that makes sense.. Will have to take some pictures.
Not sure if this is how the flaps Should be, but it runs perfect so maybe the carbs have been tuned with them I this position.
So if you try to move the weight, it won't moved as it is wedged in the open position. This is done by wedging the little tab over the ridge at the end of the air tube housing.
Really need some pictures!

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broady_6
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Re: What's going on after spark plug change?

Post by broady_6 » 9th April 2019 - 9:31am

Ah ha, As dave said thats generally a setting for a hot country. Sounds like its worth having your engine gas analysed and maybe set up for scratch.
The sultan of swing

kinga
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Re: What's going on after spark plug change?

Post by kinga » 9th April 2019 - 11:08am

It runs that well, not gonna mess!
Pulls well, spark plugs look good, and it's good on fuel!

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broady_6
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Re: What's going on after spark plug change?

Post by broady_6 » 9th April 2019 - 11:22am

Ok ill take a dose of, if it aint broke dont fix tit then :D
The sultan of swing

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