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CAV filter swirl pot


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Hi All.

Has anyone got pictures of a CAV filter used as a swirl pot ?

Just wondering if it would be the cheep option. Also anyone run pre pump ? I know Harrytr5 does with good results. Just wondering which pump.

Cheers Mark.

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A Facet Red Top can be used, but isn't necessary as long as your roller vane main pump has enough head & the largest possible cross-sectional area at the feed end to avoid vapour lock.

Swirl pot: the original CAV filter head allows the fuel to be drawn out from the top, above the filter; on original TR5s & early 6s, surge issues are maddening.

Find a length of thin wall metal tube that fits neatly over the end of the O-ringed central spigot inside the filter cap, long enough to extend into the bottom of the cup & you immediately have a neat reservoir of circa 3/4pt capacity to draw from.

I daresay the larger CAV filter assemblies seen on some commercials & tractors could be adapted to provide greater capacity still.

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" Find a length of thin wall metal tube that fits neatly over the end of the O-ringed central spigot inside the filter cap, long enough to extend into the bottom of the cup & you immediately have a neat reservoir of circa 3/4pt capacity to draw from.
I daresay the larger CAV filter assemblies seen on some commercials & tractors could be adapted to provide greater capacity still "

 

In the past I've found the adapted CAV swirl pot as Jon describes quite adequate to cure problems of fuel starvation on cornering - on cars faster and more powerful than TRs.

 

The larger tractor type CAV housings will indeed do the same job satisfactorily for larger capacity engines.

 

An economical solution !

 

Cheers

 

Alec

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As a small reservoir, kept full by a primary pump, a filter housing would be fine. I think that the cheaper Facet SolidState pump would have sufficient capacity.

 

But a "swirl pot" has a different design. Fuel is delivered to the cylindrical tank (pot) tangentially, so that the fuel in the pot is kept spinning, 'swirling'.

The 'centrifugal force' induced by this movement forces any bubbles to the centre, where a take off returns surplus fuel and bubbles to the tank.

The takeoff to the main pump is taken from the outer edge of the base of the pot, where no bubbles can be guaranteed, even if a low tank level and vigourous cornering exposes the pickup pipe in the tank to air.

 

John

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Hi Naill

I've got one, bought it ages ago. To be honest I took it out as it didn't cure the problem I had at the time.The problem is noise from the pump, I've changed the pump and still have the noise, so it's something to do with the set up. Perhaps I should re fit it ?

Mark.

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A Facet Red Top can be used, but isn't necessary as long as your roller vane main pump has enough head & the largest possible cross-sectional area at the feed end to avoid vapour lock.

Swirl pot: the original CAV filter head allows the fuel to be drawn out from the top, above the filter; on original TR5s & early 6s, surge issues are maddening.

Find a length of thin wall metal tube that fits neatly over the end of the O-ringed central spigot inside the filter cap, long enough to extend into the bottom of the cup & you immediately have a neat reservoir of circa 3/4pt capacity to draw from.

I daresay the larger CAV filter assemblies seen on some commercials & tractors could be adapted to provide greater capacity still.

 

You would ideally also connect up one of the other "inlet" options so that it can vent the air in there back to the top of the tank. Otherwise the bubble of air simply sits in the top of the filter housing until it can burp back into the bottom of the tank or gets sucked into the pump.

 

My experience with running the roller vane pump alone is that they struggle without the facet lift pump & tend to cavitate without, especially as they age.

 

Is the noise very loud? Like a constant hum rather than the sound of the pump? In which case it may be resonance of the pipework and PRV.

Gripping the the flexible high pressure line from the pump to PRV may alter the frequency in which case change the length of the flexi pipe or fit a diaphragm PRV as the issue is a matter of tune length - the sprung valve in the prv setting up a resonance in the pipe work. Changing the pipe length is like a trombonist moving he slide on the instrument to change the tuned length to a different one from the the prv rapidly oscillating to control the pressure.

 

However if it sounds like a moped revving up and slowing down that might be a stuck prv making the pump strain. Certainly had this with a Bosch pump stuck at 150 psi!

Edited by andymoltu
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Nee need for sna a TR,

IF ye bung an outlet on each end of tank, linked into a bigg filter

tank then becomes a swirl,

ne need for pre lifter pumps either.

 

So so simples

 

M

 

You don't need to create an extra outlet when you can use the existing returns to the top of the tank - just a "t" piece.

 

Having tried the roller vane pump with and without a lifter pump my experience is different. They are ok when new but get stuck in traffic and they tend to cavitate in hot weather. Much the same problem as a Lucas pump but at least they reliably pump the volume at pressure.

No need for a lifter with a Bosch.

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Hi Naill

I've got one, bought it ages ago. To be honest I took it out as it didn't cure the problem I had at the time.The problem is noise from the pump, I've changed the pump and still have the noise, so it's something to do with the set up. Perhaps I should re fit it ?

Mark.

Hi Mark can you Photo the set up you now have as we might see a problem,strange your getting the same symptoms with 2 different Pumps.
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Hi Nail.

I've converted to EFI so it's slightly different. From the tank to pre filter straight into pump then onto the fuel rail then pressure regulator and back to the tank. I fitted the original Bosch pump back but had the same results.

Cheers Mark.

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There isn't one Naill, there's a pressure regulator but that keeps a constant pressure behind it the PRV kept the pressure in front of it.

Personally think the in tank idea might be the way to go.

Mark.

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Ahaa, yer no on PI, butt ye only need about 30-40 PSI now with EFI and its pump

{ ditch what P Pat an his Cat sent !! }

 

You prob have issues wid the return,

as wen fuel come oot of compression,it blows up, { like a shook up pop bottle, wen opened,wot happens, !! }

this stuff,fuel, wen got back into tank ,turns t,froth, as ther now nowt t,keep it in compression

 

efta a short while, esp on low fuel, the tank becomes filled wid zillions of wee bubbles,

or moer like a frothy beer,just pulled.

yer pump then sucks this in, an cavitates

 

solutionee, is a bigg filter on the return, an a bigg pree filter, wid inlet into to, outlet t,pump at bottom

this so pump aint suck,n frothed up fuel, or air bubbles cause by a starvation prob whenst cornering.

 

its no as bad as a PIs return frae PRV,

as pressure aint as great on EFI, butt, it still does it.

can v v easily be seen whenst using clear filters,or lines or both as I did, t fin this oot.yonks ago.

 

Andy, yee,v had probs cos of the lack of filters in yer system, { said it loadsa times }

and Filters fitted correct way up, and fuel tek,n frae the bottom,

 

not like all the sheite that the so called specialist sell., has any one ever seen a Deisel filter onits side,nope, enuff said.

yer pumps suck,n frothed fuel, its a vicious circle esp wid low fuel, an hot fuel.

caused by yer return frae engine t,tank, yer pump, and hot weather heating yer tank, simples.

 

even moderns get it, thats why lots ev got fuel coolers on em.look into it, see for yer self.

 

M

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+1 for GT6M post.

 

If you are using a pump designed for the PI system, you're generating more than double the fuel pressure required for efi .

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Worth noting also that if you are planning a very high output engine, some of the orifices inside the CAV filter head are rather restrictive; it's a straightforward task to enlarge everything by drilling & retapping where required.

We used to enlarge the main metering unit feed too, post-PRV, to dash6 instead of the original dash5.

The amount of tweaking required to a TR Lucas PI to make it run really well on a proper race engine is barmy.

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The amount of tweaking required to a TR Lucas PI to make it run really well on a proper race engine is barmy.

 

Problem is detected but the solution is really poor.

You should take a look at my picture.

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