Jump to content
Dark Mode Now Availiable (Change via theme selector at the bottom of the site)
Saint Jimi

Facet pump + weber carb

Recommended Posts

Saint Jimi

Hi all. I know there is a lot of information on here already about the subject but I'm afraid I haven't been able to find the right information for my specific set up by searching previous threads. 

 

I'll be putting a GT cam in my mk2 in a couple of weeks and want to make sure I've got all the parts ready before I start. I'm confident that I can do the cam swap with my previous experience and the guide in faq. 

 

What I'm still stuck with is the fuel pump. Most of the info on here relates to what to use if you're running bike carbs, but I've got a weber carb (28/32 iirc) and don't know what pressure I need. I've spoken to a friend who says the pressure on facet pumps is adjustable but from what I've seen this isn't the case.

 

I've also looked at the specs of the standard mech pump which says at 1000rpm it pumps at.0.20 - 0.25 bar. Which is a useful starting point but this presumably increases with revs.

 

I've also read about using a ways of dealing with excess fuel, my carb definitely has a fuel in pipe and a second pipe that returns fuel to the tank. I have always referred to this second one as fuel return. Does this mean that I can have a set pressure fuel pump which may pump too much but any unused fuel will be returned to the tank anyway? 

 

If that's the case what bar / psi facet pump should I be looking for? Links would be appreciated. 

 

(all these questions and I haven't even got to the inertia switch yet) 😣

Edited by Saint Jimi
Spelling / autocorrect

Share this post


Link to post
Share on other sites
dvderlm

Carbs need volume not pressure. I'd say max 5psi and mount a Facet as low and as near tank  as you can, they prefer to push.

You don't want to overwhelm the needle valve, it only closes because a hollow plastic float has buoyancy in petrol in carb well. 

 

Or get a Huco suction pump?

  • Thanks 1

Share this post


Link to post
Share on other sites
steveo3002

fitted a gt cam to mine...not worth the hassle , very little difference and wouldnt have been worth all the mods to plumb in a pump

 

newman make cams with the pump lobe ...easy fit and more aggresive profiles available 

  • Like 1

Share this post


Link to post
Share on other sites
Saint Jimi

Steveo, you are now the second person to suggest that. I hadn't considered that option as I thought it might be way out of budget, I'll look into it though. Any idea what sort of price I'd be looking at for a Newman cam, also does Jackson tuning still do them, I've seen him referenced in old posts but can't find his section of the forum. 

Share this post


Link to post
Share on other sites
steveo3002

jackson isnt in buisness anymore ...theyre around 200£ plus posty, email them they will answer any questions

 

neater and nicer option than bodged up fuel pumps that never work right imo

Share this post


Link to post
Share on other sites
Saint Jimi

Thanks. Based on what I've heard from all sources I might scrap the whole idea and save up for a Newman cam.

Maybe back to the drawing board with sourcing an abd block/engine and building on that with a Newman cam in the head.

Share this post


Link to post
Share on other sites
Saint Jimi

This new decision brings me on to a new line of questioning. What 8v 1.4 engines are a straight swap, is it literally just the abd lumps from golf/vento or are there other more readily available options? 

Share this post


Link to post
Share on other sites
kiran_182
11 hours ago, steveo3002 said:

fitted a gt cam to mine...not worth the hassle , very little difference and wouldnt have been worth all the mods to plumb in a pump

 

newman make cams with the pump lobe ...easy fit and more aggresive profiles available 

 

270 was the best thing i ever did 

Share this post


Link to post
Share on other sites
kiran_182
2 hours ago, Saint Jimi said:

This new decision brings me on to a new line of questioning. What 8v 1.4 engines are a straight swap, is it literally just the abd lumps from golf/vento or are there other more readily available options? 

 

Really you need to convert to 2f gt injection to get the benefit of a cam or newer engine. Abd used a 3f block but has a longer stroke. The best mix would be a abd crank with 3f pistons 1.4cc 10.1 compression 

Share this post


Link to post
Share on other sites
Saint Jimi

Despite being advised against it I got bored last weekend and put the GT cam in with a facet pump. All seemed well until I set out on a 200 mile round trip last night. 

 

I seem to be suffering from a problem that I had read might be a potential issue, so before I write the whole idea off and temporarily revert back to standard cam and mech pump I'm wondering if anyone has a solution. 

 

It's when cruising for significant periods of time at motorway speeds the car starts spluttering, indicating to me that it's not receiving enough fuel, forcing me to drop to about 40mph just to keep moving. I've read talk of including a swirl pot into the equation pre carb, but can't remember what issue that was supposed to help with. 

 

Any thoughts, the pump is this one. https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F122965577695

 

Also could it be that I've gone overboard on fuel filters with a plastic in line one before the pump, then the metal one that comes with the pump, and finally the one that the car has always had in the engine bay. How much resistance is there in a filter and would it add up to fuel starvation?

 

Edit: I just found the thread that mentioned the fuel starvation (below), I think it was referring to bike carbs rather than webber with a fuel in and return. But having said that, should I have bought a bike fuel pump instead? (comments by prankster & Buxton) 

 

Edited by Saint Jimi
More info

Share this post


Link to post
Share on other sites
dvderlm

How is it plumbed in? t-piece or with a pressure regulator?

And low down?

You might be able to restrict the return flow.

I have seen a bar and a jubilee clip squashing the return pipe.

 

Don't need much fuel at constant speed on the flat up to around  60mph, when the wind resistance has a noticeable effect. 

Share this post


Link to post
Share on other sites
Saint Jimi

I haven't used a t piece or regulator as there is a fuel return pipe from the carb. I could probably mount it a bit lower with a bit of ingenuity which I will try tomorrow but currently it sits at about half the height of the fuel tank.

 

Currently it is all hanging quite lose on the rear foot well behind the drivers seat with a maximum of two foot of pipe between the tank and pump, then output of electric pump being another two foot before going back to the external pipes that run beneath the car. 

 

I could try squashing the return pipe with a jubilee clip if you think it'll help. What do you mean by "a bar"? 

 

Thanks for your reply. 

Edited by Saint Jimi
Further details for clarity.

Share this post


Link to post
Share on other sites
dvderlm

Sounds low enough, was fuel tank more than half full when it stuttered?

 

 

bar - A smooth round piece of metal or wood about 7 to 10mm diameter. Put jubilee clip around bar and pipe, tighten to constrict. It lets you use a bigger jubilee clip and squashes one side of pipe in.

 

I'd remove the post pump filter. There is one in the carb. Small brass nut below inlet/outlet pipes on DMTL, Maybe that is clogged.

Edited by dvderlm

Share this post


Link to post
Share on other sites
Saint Jimi

The tank was filled when I started my journey and was a quarter full by the end. I'll try getting the pump even lower, restricting the return, removing engine bay filter, and I'll check the in carb filter you mentioned. Cheers. 

Share this post


Link to post
Share on other sites
VwDan

How did you get on, I'm about to start going down the same route

Share this post


Link to post
Share on other sites
Saint Jimi

I have done all of the above, including restricting the return flow ever so slightly with a bar as suggested. I think the thing that made the most significant difference was lowering the pump level with the bottom of the tank, there's been no spluttering since. It's weird though, some days it feels like the cam has made a huge difference and other times I'm less sure. 

 

Part of me has lost enthusiasm for it a little bit which is why I hadn't replied. I think my bottom end is getting a bit tired (smoke puffing out of the large breather pipe that connects to the air box). Possibly a result of improving the oomph of the head without shoring up the bottom. 

 

I'm also feeling a bit gutted about drilling holes into the car to mount the pump where I originally had it only to have to move it underneath anyway. 

 

My advice is get the smallest facet pump you can find that'll do the job (mine is on the large side so limits where I can put it) and put it under the car in the first place. 

Edited by Saint Jimi

Share this post


Link to post
Share on other sites
dvderlm

With hot engine does it feel better on cold days or at night?

If yes you might be able to lean the main jet.

Or if you pull the choke on a bit and goes better, then you might be able to richen the main..

 

But cylinder hone, new big-end bearings and piston re-ring is job you can do with engine in place. 

Share this post


Link to post
Share on other sites
Saint Jimi

I'm not sure if temperature or choke is making much difference, I haven't really had the opportune conditions to test this theory as sometimes I'm on my own, sometimes I've had passengers so extra weight, too many variables to judge. 

 

As long as this engine gets through the mot on emissions in a couple of months I'm probably going to have to leave it for now, not enough time to do it myself and not enough money to pay someone else for it.

 

Regarding the main jet, how can I determine the size of the one in it currently (are they marked)? Can you still buy jets from weber? 

Share this post


Link to post
Share on other sites
VwDan

was looking at pumps but there is a lot of choice on ebay, hard to know which one will do the job right

Share this post


Link to post
Share on other sites
Saint Jimi

This is what I got, seems to work fine as long as it is fitted as low as possible. It was originally in the body cavity under where the drivers side seat belt bolts and didn't do the job, so then I just laid it in the foot well behind drivers seat and still not up to it. Finally it's now under the car level with the bottom of the tank. 

 

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F122965577695

Edited by Saint Jimi
  • Like 1

Share this post


Link to post
Share on other sites
dvderlm
9 hours ago, Saint Jimi said:

Regarding the main jet, how can I determine the size of the one in it currently (are they marked)? Can you still buy jets from weber? 

There are 2 main jets in twin choke weber. It's the secondary stage main jet I'm on about.

This feeds the venturi without a choke flap. The passage from that venturi points to the secondary stage jets

 

They simply unscrew with tight fitting screwdriver. Idle jet is usually size 70 and small. Three parts to the main jet stack. Air corrector, emulsion tube and main fuel jet.

They should all have makings.

I'd expect something like 110 / F30 / 185 (guess from memory) for main/emulsion/air.

 

(if you find F22 emulsion that is more likely to be primary stage - depends how much if at all anyone has already messed with it, or which car it came from). 

Try seller fastroadcars or eurocarb or webcon or the greensparkplug company via ebay. Watch out for postage, most will combine if you buy a few jets in range.

 

 

If remove both, always put the main jet back first.

 

Edited by dvderlm
  • Like 1
  • Thanks 1

Share this post


Link to post
Share on other sites
Saint Jimi

So I was totally broke for a while but have had enough spare £££s to buy a few jets and have a bit of a play. For those who were disappointed with their GT cam upgrades I can say for me at least that increasing the size of the jets have completely transformed the car. It really feels like it's had a significant performance increase now. 

 

I've gone from what was basically the standard jetting for a 1.3 polo to raising the size of each jet by a few sizes and definitely don't regret it. When I fitted the carb years agoand had a local company set it up the carb was the only upgrade. 

 

Since then I have opened up the inlet manifold, fitted a performance stainless steel exhaust, k&n filter, and GT cam. The standard jetting just wasn't cutting it. 

 

I have a terrible memory so can't remember what jets I went for but will update this thread once I've reminded myself. 

 

Thanks for everyone's help and advice with this along the way, I intend to take it to a rolling road at some point in the next few months. I will update this thread with the jets I'm using and the results of the rolling road when I get round to it. 

Share this post


Link to post
Share on other sites
nige8021

Saturday 6th April, we are running our annual rolling Road session https://www.clubpolo.co.uk/topic/357882-club-polo-rolling-road-day-saturday-6th-april-2019/?tab=comments#comment-2730926  would be good to see you there 👍

 

Share this post


Link to post
Share on other sites
Saint Jimi

I was toying with the idea of coming to that but it's a bloody long way and a very early start for a day trip. If I could make a weekend of it I'd be more likely to be up for it but for just a couple of hours only to drive all the way home again I'm not so keen. 

Share this post


Link to post
Share on other sites
dvderlm

We do tend to end up going somewhere for nosh and a none-alcoholic beverage before driving home so it can be more of a day trip.

I have also heard legends of a Wolverhampton or Dudley disco dancing establishment but fear it no longer exists. 

 

This town, is coming like a ghost town.

All the clubs have been closed down.

Bands won't play no more.

 

  • Like 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. Terms of Use Privacy Policy Guidelines