I can't get the van to run smoothly on petrol when the mixer ring is fitted.

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LPGC
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Re: I can't get the van to run smoothly on petrol when the mixer ring is fitted.

#21 Post by LPGC » Sat Jul 17, 2021 10:45 pm

I agree, would definitely move the vent pipe.
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David James
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Re: I can't get the van to run smoothly on petrol when the mixer ring is fitted.

#22 Post by David James » Wed Jul 21, 2021 5:29 pm

This is where I am so far.
I have the pipes where I thing they should go. The mixer is set back further from the carb and the breather is connected to the air intake box. There would of originally been a heat exchange pipe from the exhaust manifold operating an air flap. This is long gone, and I thought it would be a good place to insert the crank breather pipe, so save making any more holes.
The other picture shows the hole cut by the original installers.

Please let me know if you can see any issues with how I have things set, or it there is anything I can do to improve it. Thanks again.
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Pipe Flow.jpg
Pipe Flow.jpg (259.58 KiB) Viewed 264 times
Breather Flow.jpg
Breather Flow.jpg (207.13 KiB) Viewed 264 times
Hole.jpg
Hole.jpg (166.82 KiB) Viewed 264 times
Last edited by David James on Wed Jul 21, 2021 5:47 pm, edited 1 time in total.

Brian_H
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Re: I can't get the van to run smoothly on petrol when the mixer ring is fitted.

#23 Post by Brian_H » Wed Jul 21, 2021 5:36 pm

Doesn't seem to be any photos posted, no url in the links there?

Pinger
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Re: I can't get the van to run smoothly on petrol when the mixer ring is fitted.

#24 Post by Pinger » Wed Jul 21, 2021 6:11 pm

I can see the photos - and not much wrong with what you've done to my eyes.
With the exception of routing the breather upstream from the air filter. If is a full PCV system then unfiltered air will be drawn through the crankcase. Not ideal, I'd either re-route to downstream of the filter or, fit a crankcase breather filter (£5 off ebay). But, I suspect your breather is breathing in the opposite direction in which case the only thing to watch for is oil vapours clogging the air filter element.
Ascertain if it's full PCV or mere breather and decide from there if you need to filter the air. If it is the simpler non PCV you have the gauze trap should be sufficient to keep the big filter clean - but worth keeping an eye on just in case.

David James
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Re: I can't get the van to run smoothly on petrol when the mixer ring is fitted.

#25 Post by David James » Wed Jul 21, 2021 10:47 pm

From the original location of the breather pipe I assumed that the oil vapour was being drawn up towards, and into the carb. There is also a thinner pipe coming from the gauze trap and this runs to the inlet manifold. I also assumed that the breather pipe would help with starting and running a cold engine.

It's all a learning process for me at the minute, so I'm always glad to get advice.

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Re: I can't get the van to run smoothly on petrol when the mixer ring is fitted.

#26 Post by Pinger » Thu Jul 22, 2021 4:26 pm

David James wrote:
Wed Jul 21, 2021 10:47 pm
There is also a thinner pipe coming from the gauze trap and this runs to the inlet manifold.
This thinner pipe - separate from the breather pipe in the photos, one end attaches to the inlet manifold and its other end somewhere that communicates with the crankcase (block, timing chain cover, etc) - yes?
If so, full PCV system and you would be wise to filter the incoming air that is entering the crankcase via the pipe that has been relocated.
David James wrote:
Wed Jul 21, 2021 10:47 pm
I also assumed that the breather pipe would help with starting and running a cold engine.
Nope, afraid not. It's function is purely to prevent emissions to atmosphere. The inlet end of the air filter where it was once ducted to the exhaust manifold would have helped the warm up but being able to switch to LPG before full operating temp is reached circumvents the need. It was really to aid petrol atomisation.

David James
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Re: I can't get the van to run smoothly on petrol when the mixer ring is fitted.

#27 Post by David James » Thu Jul 22, 2021 5:11 pm

So it would seem to be full PCV. Why would I need to filter the air on the relocated pipe, and would the gauze trap be enough of a filter, or are you thinking that I should pass it through the air filter.

The carburettor base is also connected to the water system, which I presume is also to help get heat into the carb and aid petrol atomisation.

Brian_H
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Re: I can't get the van to run smoothly on petrol when the mixer ring is fitted.

#28 Post by Brian_H » Thu Jul 22, 2021 6:35 pm

I'd read the reasoning above to suggest your filtering it to stop stuff getting back down into the crankcase via that route rather than to stop anything coming up from the crankcase. A lot of older Ford's I've had have had the breather before the air filter, those typically use a sponge block in the bottom of the air filter housing where the breather joins to the box for that sort of purpose.

Pinger
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Re: I can't get the van to run smoothly on petrol when the mixer ring is fitted.

#29 Post by Pinger » Thu Jul 22, 2021 7:01 pm

David James wrote:
Thu Jul 22, 2021 5:11 pm
So it would seem to be full PCV. Why would I need to filter the air on the relocated pipe, and would the gauze trap be enough of a filter, or are you thinking that I should pass it through the air filter.
Air enters the crankcase, circulates within it, and is then ingested by the cylinders along with the air fuel mix via the pipe to the manifold. Thus, the air needs to be filtered to prevent the ingress of dirt to the crankcase.
Which pipe is the gauze filter in (the relocated one)? Does it look like it offers the same level of filtration as the main air filter (or is it a much coarser affair)?
Relocation upstream of the mixer may affect calibration (ie mixture strength) but if it is running fine then less of a concern.
(FWIW, I use a small crankcase filter on the end of the pipe that feeds air to the crankcase. A simple solution though I should probably draw air from the main air filter).
David James wrote:
Thu Jul 22, 2021 5:11 pm
The carburettor base is also connected to the water system, which I presume is also to help get heat into the carb and aid petrol atomisation.
Yes, water heated manifold for exactly that.

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