Holley Carb Problem

[Warren]

Hi Mike, thanks for the pointers

In this case I think it could be a backfire. It's ticking over, full operating temperature and every few seconds theres a pop from the driverside exhaust.

Got a few things to get done today but may have time for a look at it later.

Cheers
Warren

[craggle]

Sorry to sound like a broken record Warren, But it's really not a good idea to have a fuel filter on top of the engine that is made of plastic or glass.
The temperature on top of the motor will be enough to soften the plastic and it could split spraying fuel on the hot exhaust headers.

Keep the filter near the back of the car before the filter or use one of the Filter King type filters in the engine bay. These are designed to withstand temperatures under the bonnet.

Cheers

Craig.

[mikey]

Originally Posted by Warren

Hi Mike, thanks for the pointers

In this case I think it could be a backfire. It's ticking over, full operating temperature and every few seconds theres a pop from the driverside exhaust.

Got a few things to get done today but may have time for a look at it later.

Cheers
Warren

If thats the case my guess it is one of the plugs or leads on that bank. basically the charge in one cylinder will not be fired and is then being passed out of the exhaust port. It is probably then being ignited in the header causing a pop/crackle in the exhaust. If it was timing it would be unusual to get in one one bank.

Mike

[Warren]

Originally Posted by craggle

Sorry to sound like a broken record Warren, But it's really not a good idea to have a fuel filter on top of the engine that is made of plastic or glass.
The temperature on top of the motor will be enough to soften the plastic and it could split spraying fuel on the hot exhaust headers.

Keep the filter near the back of the car before the filter or use one of the Filter King type filters in the engine bay. These are designed to withstand temperatures under the bonnet.

Cheers

Craig.

Hi Craig

I have already got one inline filter toward the back of the car but saw a thread somewhere suggesting one on the tank outlet and another between fuel pump and carb. My pump is mechanical so at the moment that spot there is the coolest spot.

I knew about the problems with the glass ones are the plastic ones susceptible as well?

Filter king type? Any specific type?

Cheers
Warren

[Warren]

Originally Posted by mikey

If thats the case my guess it is one of the plugs or leads on that bank. basically the charge in one cylinder will not be fired and is then being passed out of the exhaust port. It is probably then being ignited in the header causing a pop/crackle in the exhaust. If it was timing it would be unusual to get in one one bank.

Mike

Hi Mike, I agree, I'm going to whip out the plugs for a look see before I get it hot later. I marked the dizzy after the car had been set up at Bogg Brothers and it hasn't shifted so I am ignoring the timing possibility at the moment.

I'm thinking that it's possible that more crap has got into the carb effecting idle mixture. So the plan it to check the plugs, clean the carb again checking the idle mixture screws in particular and go from there.

Cheers
Warren

[craggle]

I have never seen the need for 2 filters myself. Filtering the fuel before it gets to the pump is good practice as it protects the pump valves and diaphragms from dirt.
The only stuff that is going to come out the pump is fuel as clean as it was when you put it into the pump. If the pump starts breaking up and shedding debris into the fuel then you are likely to stop fairly soon anyway.

I would go back to one filter before the pump.

Craig.

[Alex Leake]

Had the same problem last Monday. Took float chamber off and found black plastic float was discoloured, been reliably informed that it probably has a hole in it and may not be rising when chamber is full on slowing revs.
Regards
Alex

[Warren]

Erm, I think I fixed it, notice the immediate claim of triumph over adversity

For those following this I took out the plugs and they were mucky, carbony but bearing in mind this problem starting with s stuck float and petrol pooring down the throat of the carb this will have run very rich the ten miles home. So I cleaned em up and put them back in.

I checked both float levels and the one at the rear was still a little high so I readjusted that.

The carb looked clean throughout so I started it and ran it up to temp, sounded a bit rough and then I noticed a plug lead not replaced after checking plugs. That's better. Now I checked the idle screws, nearside seemed to have no effect what so ever, offside I was expecting to lean off but it stopped after about half a turn, weird, as I turned it back I suddenly got improved tickover, really nice. Tried the nearside and maybe a slight change but barely discernable. Not wishing to move these screws too far I adjusted the idle down and it sounds sweet. Daren't take it out yet as Craig has put the wind up me with the plastic fuel filter and I haven't any spare petrol pipe 'til tomorrow when I will take it for a spin. Even sticking it back in the garage er in doors say, 'that's sounds better'.

One comment I would be interested in hearing feedback on. These idle mixture needles don't have any springs behind them and turn with the lightest of pressure, anyone else found this?

Cheers & thanks to those helping out with suggestions.

Warren

[Clarkson]

Originally Posted by Warren

Erm, I think I fixed it, notice the immediate claim of triumph over adversity

For those following this I took out the plugs and they were mucky, carbony but bearing in mind this problem starting with s stuck float and petrol pooring down the throat of the carb this will have run very rich the ten miles home. So I cleaned em up and put them back in.

I checked both float levels and the one at the rear was still a little high so I readjusted that.

The carb looked clean throughout so I started it and ran it up to temp, sounded a bit rough and then I noticed a plug lead not replaced after checking plugs. That's better. Now I checked the idle screws, nearside seemed to have no effect what so ever, offside I was expecting to lean off but it stopped after about half a turn, weird, as I turned it back I suddenly got improved tickover, really nice. Tried the nearside and maybe a slight change but barely discernable. Not wishing to move these screws too far I adjusted the idle down and it sounds sweet. Daren't take it out yet as Craig has put the wind up me with the plastic fuel filter and I haven't any spare petrol pipe 'til tomorrow when I will take it for a spin. Even sticking it back in the garage er in doors say, 'that's sounds better'.

One comment I would be interested in hearing feedback on. These idle mixture needles don't have any springs behind them and turn with the lightest of pressure, anyone else found this?

Cheers & thanks to those helping out with suggestions.

Warren

Still sounds like your carb is full of shit!

[Warren]

Originally Posted by Clarkson

Still sounds like your carb is full of shit!

Hee, hee, hee, it's not, I've had it in bits today but you made me laugh.

Anything more helpful David?

Cheers
Warren