The Peerless & Warwick Discussion Forum

mikerf · Status: Offline

Fuel pipe sizes and routing

Erik V · Status: Offline

For question two:

The SU pumps use mechanical valves, so I guess when one is pumping the other pumps valves are blocking the fuel to go through it?

Don't know if the Huco pumps use the same principle.

Erik V · Status: Offline

If it's this one it's described as using mechanical valves, so no need for one way valves I think.

Nice pump, looks a bit like an SU.

Huco pomp.JPG

-- Edited by Erik V on Wednesday 2nd of September 2020 11:51:45 AM

mikerf · Status: Offline

Yep, thems the ones Erik. Half the price of SU items.

Guess I'm pretty stupid. Should have thought of that myself. I think lockdown brain-fade is having it's effect on me.

Frank · Status: Offline

A "known problem" with the SU pumps is that the non return bit is not that efficient, with some much worse than others. So if you fill both tanks, a bit of the fuel leaks back past the non-running pump and the tank overflows. Cue strong smell of petrol coming in the back window. I don't know if the HUCO pumps will give the same effect.

Only a problem if you can afford to fill both tanks at the same time.

F

Frank · Status: Offline

A "known problem" with the SU pumps is that the non return bit is not that efficient, with some much worse than others. So if you fill both tanks, a bit of the fuel leaks back past the non-running pump and the tank overflows. Cue strong smell of petrol coming in the back window. I don't know if the HUCO pumps will give the same effect.

Only a problem if you can afford to fill both tanks at the same time.

F

Erik V · Status: Offline

I see no harm in placing a couple of one way valves, if the pumps non return bit is not working properly

mikerf · Status: Offline

Frank wrote:

Only a problem if you can afford to fill both tanks at the same time.
F

A good idea, Frank. I'll keep the offside one topped up. That will compensate for my weight in the drivers seat.

Just as a point of interest, I spoke to Southern Carbs to see if there was such a thing as replacement top piece with 6mm i/d unions. The answer was, probably in Germany (where they're made) but not in the UK. Apparently they're commonly used with Webers (which take a 8mm i/d pipe) which would make sense as it was on one of the Lotus forums that I read the positive reviews.

nigel c · Status: Offline

I got into a spiral of pain with my mate who set up my carbs etc on his rolling road as he found the SU's were starving the carbs at "full chat" and wouldn't settle until I had replaced the pumps with high pressure Facet pumps. this I did and then the pressure was to high so I had to fit a pressure regulator/filter. not a bad idea but more cost/time/where the f**k do I fit it!

Anyhoo, then we found it was filling either tank when switch over etc so then fitted in line one way valves....... fianally he was happy and finished setting it up.

have to say I wasnt to happy as I had a lot more joints in the system than standard and what do joints make...no, not happy little junkies..joints mean leaks.

and relax.......

wingleton · Status: Offline

I went for Facet pumps when doing the rebuild several years but they pumped fuel between tanks so ended up fitting one way valves as a result. All very annoying and time consuming....

The Facet pumps were ok if a little unreliable (got through three over 11 years)probably due to not being able to mount them vertically (their preferred axis) because of the lack of room behind the seats. I've not heard of the Huco pumps before but they look the part.

I have changed back to SU's this year and they seem to manage well under load at high revs etc. I have kept the one way valves just in case.

Will

mikerf · Status: Offline

Well, I'm glad I asked the question and am thankful for all the replies. When I sat down and looked at the system it did occur to me that it wasn't ideal and there was always the potential for the pumps pushing fuel from one tank to the other.

Just out of curiosity, what pressure were the the Facet pumps pumping at?? My Huco ones are 3.6 psi and I'm now wondering if a filter/regulator might be necessary in addition to the one-way valves which have now found their way on to my shopping list.

Any consensus of thought on best place to fit them? Next to the pumps, I would assume?

Frank · Status: Offline

I used a Facet solid state pump with a separate pressure regulator but still get starvation if I'm too long at full bore. It keeps me out of trouble, but will upgrade to a Facet blue top (38 GPI at 7psi) and 8mm pipes at some point.

Looking at the HUCO 133010, it seems to be a "suck" pump, to be fitted under the bonnet. Have I got this wrong?

F

nigel c · Status: Offline

on the routing side of things, I took mine down the RH side of the car, up into the void behind the door hinge plate and straight round to the carb feeding 3 & 4. I think the official route was on the other side of the engine and the feed comes over the water pump and in. I realise that the TR's are like that because of the manual pump but I didn't like it over the engine. everyone has a preference.

mikerf · Status: Offline

Frank, I bought the Huco 133000. They're the 'pusher' type for installation by the tank but you're correct, the 133010 are suckers. The Hucos are supposed to be a direct replacement for the SU ones.

Re routing, I've followed what I believe was the original, down the trans tunnel, up the bulkhead at the nearside and over the water pump as per TR's but using braided hose.

mikerf · Status: Offline

Frank wrote:
It keeps me out of trouble, but will upgrade to a Facet blue top (38 GPI at 7psi) and 8mm pipes at some point.
F

Frank. I'd be interested in hearing how you'd intend to fit an 8mm pipe to SU carbs (provided that's what you run).

I had a chat with the SU guys at Burlin and apparently float chamber lids with an 8mm inlet pipe don't exist, at least for HS6 carbs. They only come in 6mm dia.

Frank · Status: Offline

Short answer: 8mms to a T junction between the carbs, 6mm to each carb.

Long answer: I can't work out why I'm getting fuel starvation. The engine has eased in a treat, and pulls really well from 3 to 5K. It only complains it I spend too long at full throttle. The fuel pump and pressure regulator are in the offside sill, and the pipe runs forward and up the bulkhead to behind the carbs. There's no obvious kinks or blockages, and hardly any pipe under the bonnet to get too hot. I'm trying to get a rolling road session to see where I am, but if it's disappointing then it'll be bigger valves and DCOEs this winter.

F

mikerf · Status: Offline

That's interesting. I was trying to decide whether to put an 8 to 6mm T piece at the rear and run a 6mm pipe to the front or do what you're intending and run 8mm pipe to the front and use an 8 to 6mm reducer prior to feeding into the front carb and 6mm between the carbs.

At least with DCOE's you can have 8mm all the way. An expensive option, though.

gav12 · Status: Offline

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